"Glossary of Geology" "D"

dachiardite

A monoclinic mineral, (Ca,Na2 ,K2 )5 Al10 Si
38 O96 .25H2 O ; zeolite group; in a pegmatite at San
Piero, Elba, Italy.

dacite

A fine-grained extrusive rock with the same general composition as
andesite, but having a less calcic plagioclase and more quartz; according
to many, it is the extrusive equivalent of granodiorite.
Syn:quartz andesite
ancient Roman province of Dacia (now part of Romania). AGI

dacker

Eng. Insufficient ventilation of a mine; dead air.

dactylitic

A term applied to a rock texture produced by a symplectic intergrowth, in
which one mineral is penetrated by fingerlike projections from another
mineral; also, said of a rock exhibiting such texture.
See also:dactylotype intergrowth; symplectic. AGI

dactylotype

A textural term applied by Shand in 1906 to the intergrowth of sodalite
with orthoclase in borolanite and its associates. The sodalite is altered
to pinitic mica and appears in threadlike or vermicular aggregates closely
packed in a matrix of orthoclase. Holmes, 2

dactylotype intergrowth

a. A mineral intergrowth in which thin successive layers resemble a
fingerprint pattern, as in some orthoclase-nepheline intergrowths.
Hess
b. A symplectic intergrowth in which fingerlike projections of one mineral
penetrate another. See also:dactylitic

dad

N. of Eng. In coal mining, to mix (combustible gases) with atmospheric air
to such an extent that the mixture is incapable of exploding. Also called
dash. See also:dashing

dadding

The circulation, control, and utilization of air produced by the fan to
ventilate the mine workings. See also:circulation of air
Nelson

Daelen mill

An early type of universal rolling mill provided with both vertical and
horizontal rolls so that a part could be rolled on all sides in one
operation. Osborne

Daeves's reagent

An etchant used to distinguish carbides in chromium steels and tungstides
in high-speed steels. The solution contains 20 g of potassium ferricyanide
and 10 g of potassium hydroxide in 100 mL of water. Osborne

dahllite

A resinous, yellowish-white carbonate-apatite mineral or association
sometimes occurring as concretionary spherulites. Now called
carbonate-hydroxylapatite. AGI

Dahlstrom's Formula

Classification through the hydrocyclone. Pryor, 3

dakeite

See:schroeckingerite

dalles

a. The rapids in a deep, narrow stream confined between the rock walls of
a canyon or gorge; e.g., The Dalles of the Columbia River where it flows
over columnar basalt. AGI
b. A steep-sided part of a stream channel, near the dalles proper, marked
by clefts, ravines, or gorges; e.g., along the Wisconsin River,
WI.---Etymol: French plural of dalle, gutter. Syn:dells

Dalton's law

In a mixture of gases, the total pressure is equal to the sum of the
pressures that the gases would exert separately.
See also:partial pressure

dalyite

A triclinic mineral, K2 ZrSi6 O15 ; at Ascension
Island in the Atlantic Ocean.

dam

a. A barrier to keep foul air or water, from mine workings.
See also:stopping; bulkhead. Fay
b. An airtight barrier to isolate underground workings that are on fire.
CTD
c. The wall of refractory material, forming the front of the forehearth of
a blast furnace, that is built on the inside of a supporting iron plate
(dam plate). Iron is tapped through a hole in the dam, and cinder through
a notch in the top of the dam. See also:Lurmann front

dam gradation

See:contragradation

damkjernite

A hypabyssal rock composed of phenocrysts of biotite and titanaugite in a
fine-grained groundmass of pyroxene, biotite, perovskite, and magnetite,
with interstitial nepheline, microcline, and calcite. The name, given by
Broegger in 1921, is for the locality Damkjern (or Damtjern), Fen complex,
Norway. Also spelled: damtjernite. AGI

damp

Any mine gas, or mixture of gases, particularly those deficient in oxygen.
Damp is probably derived from the German dampf, meaning a fog or vapor.
See also:afterdamp; blackdamp; chokedamp; combustible gases; firedamp;
stinkdamp; white damp. Nelson

damping

a. In seismology, a resistance, contrary to friction, independent of the
nature of the contacting surface. Being proportional to the speed of
motion, it diminishes with the latter to nothing. Schieferdecker
b. A force opposing vibration, damping acts to decrease the amplitudes of
successive free vibrations. Damping may result from internal friction
within the system, from air resistance, or from mechanical or magnetic
absorbers. CF:attenuation
c. The loss of amplitude of an oscillation, owing to absorption.
See also:critical damping; damping factor. AGI

damping constant

In damped seismographs, this term is by definition equal to one-half the
ratio of the damping resistance (force per unit velocity) to the moving
mass. It has the dimensions of a frequency. AGI

damping down

In pyrometallurgy, reduction of air supply to a furnace, to lower
temperature or reduce working rate. Pryor, 3

damping factor

The ratio of the observed damping to that required for critical damping.
See also:damping

damping ratio

a. The damping ratio for a system with viscous damping is the ratio of the
actual damping coefficient to the critical damping coefficient.
Hunt
b. The ratio of two equiphase peak amplitudes within one period of a
damped seismograph or seismometer. The ratio is always greater than unity
since the greater amplitude is divided by the succeeding amplitude.
AGI

dam plate

In a blast furnace, the cast-iron plate that supports the dam or dam stone
in front. Fay

damp sheet

S. Staff. A large sheet placed as a curtain or partition across a gate
road to stop and turn an air current.

dampy

Mid. Mine air mixed with so much carbonic acid gas as to cause the lights
to burn badly or to go out.

damsite testing

Boreholes drilled to determine petrological and structural features of the
rock or overburden materials at or near the area on which the foundations
of a dam will rest. Long

dam stone

The wall of firebrick or stone enclosing the front of the hearth in a
blast furnace. Fay

dan

a. Mid. A tub or barrel, sometimes with and sometimes without wheels, in
which mine water is conveyed along underground roadways to the sump or
raised to the surface.
b. A small box or sledge for carrying coal or waste in a mine.

danaite

A cobaltoan variety of arsenopyrite.

danalite

An isometric mineral, Fe4 Be3 (SiO4 )3 S ;
vitreoresinous; forms series with genthelvite and helvite.

danburite

An orthorhombic mineral, CaB2 Si2 O8 ; resembles
topaz in habit, appearance, and properties; in marbles, low-temperature
veins, and placers.

Danian

Lowermost Paleocene or uppermost Cretaceous. AGI

Daniell cell

A primary cell, with a constant electromotive force of about 1.1 V, having
as its electrodes: (1) copper in a copper sulfate solution, and (2) zinc
in dilute sulfuric acid or zinc sulfate--the two solutions being separated
by a porous partition. Webster 3rd

Danish flint pebbles

Pebbles for grinding media, of superior hardness, toughness, and
uniformity, found on the shores of Greenland. AIME, 1

danks' puddler

A revolving mechanical puddler. See also:puddling

dannemorite

A monoclinic mineral, Mn2 (Fe2+ , Mg)5 Si8 O
22 (OH)2 ; amphibole group; has Fe2+ /(Mg + Fe
2+ ) = 0.5 to 1.0 ; columnar or fibrous; at Dannemora, Sweden.

d'Ansite

An isometric mineral, Na21 Mg(SO4 )10 Cl3 .

dant

a. Soft sooty coal found in face and back slips or cleats; fine slack
coal. CTD
b. To reduce, as a metal, to a lower temper. Standard, 2

daourite

A pink variety of elbaite.

dap

a. A notch cut in a timber to receive another timber. Zern
b. See:legs

daphnite

A magnesian variety of chamosite.

darapskite

A monoclinic mineral, Na3 (SO4 )(NO3 ).H2 O .

Darby process

A method of carburizing open hearth steel that consists of treating the
molten steel with carbon in the form of charcoal, graphite, or coke.
Osborne

darg

a. A specified day's work, usually at the coal face. See also:stint
Nelson
b. A task, or a fixed quantity of coal, agreed to be produced per shift
for a certain price. CTD
c. Scot. To work by the day. Fay
d. A north German name for meadow or moor peat buried under clay.
Tomkeieff
e. Peat formed from marine vegetation. Holmes, 2

dark ground

Indirect illumination of stage of microscope, causing objects to be
brightly displayed by oblique rays against a dark background.
Pryor, 3

dark mica

See:biotite

dark mineral

Any one of a group of rock-forming minerals that are dark-colored in thin
section, e.g., biotite, hornblende, augite. AGI

dark red silver ore

See:pyrargyrite

dark ruby silver

See:pyrargyrite

dark sulfur

Crude, dark-colored sulfur containing up to 1% oil or carbonaceous
material.

darlingite

A variety of lydian stone from Victoria, Australia. English

dashing

Eng. Increasing the amount of air in mines to prevent explosions of mine
gases. See also:dad

dashkesanite

A chlorine-rich variety of hastingsite.

dashpot

a. An appliance for damping out vibration. It consists of a piston
attached to the object to be damped and fitting loosely in a cylinder of
oil. See also:hydrabrake retarder
b. A similar device for closing the valves in a Corliss engine, actuated
by atmospheric pressure or by a contained spring. Webster 2nd

dasymeter

An instrument for testing the density of gases. It consists of a thin
glass globe, which is weighed in the gas or gases under observation, and
then in an atmosphere of known density. Osborne

dating

Age determination of naturally occurrring substances or relicts by any of
a variety of methods based on the amount of change, happening at a
constant measurable rate, in a component. The changes may be chemical, or
induced or spontaneous nuclear, and may take place over a period of time.
AGI

datolite

A monoclinic mineral, CaBSiO4 (OH) ; gadolinite group; in cracks
and cavities in diabase or basalt; may be used as a minor gem. Also
spelled datholite. Syn:humboldtite; dystome spar.

datum

a. The top or bottom of a bed of rock, or any other surface, on which
structure contours are drawn. AGI
b. Sea-level datum.--Pl: datums. AGI
c. Any numerical or geometric quantity or value that serves as a base or
reference for other quantities or values; any fixed or assumed position or
element (such as a point, line, or surface) in relation to which others
are determined, such as a level surface to which depths or heights are
referred in leveling. Pl: datums; the plural data is used for a group of
statistical or inclusive references, such as geographic data for a list of
latitudes and longitudes. See also:datum plane; geoid. AGI

datum level

Any level surface, such as mean sea level, used as a reference from which
elevations are reckoned; a datum plane. AGI

datum plane

a. A horizontal plane used as a reference from which to reckon heights or
depths. Hunt
b. A permanently established horizontal plane, surface, or level to which
soundings, ground elevations, water-surface elevations, and tidal data are
referred; e.g., mean sea level is a common datum plane used in topographic
mapping. Syn:datum level; reference level; reference plane.
See also:datum

datum water level

a. The level at which water is first struck in a shaft sunk on a reef or
gutter. Zern
b. Ground or surface water level used as a reference for all other
measurements.

dauberite

See:zippeite

daugh

a. Scot. The floor of a coal seam or where holing is done. Nelson
b. Underclay; soft fireclay. Arkell

daughter element

The element formed when a radioactive element undergoes radioactive decay.
The latter is called the parent. The daughter may or may not be
radioactive. CCD, 2

Dauphine diamond

Rock crystal variety of quartz.

Dauphine law

The law governing a twinning observed in the hexagonal system commonly
shown by quartz in which two righthand or two lefthand crystals
interpenetrate after one has revolved 180 degrees about the twinning axis.
Hess

Dauphine twinning

Transformation twinning about the [0001] direction with an irregular
contact surface in quartz. Syn:electrical twinning

D'Autriche Method

A method of geometrically determining the detonation velocity of an
explosive material by using a lead witness plate and detonating cord
ignited by the test explosive. Meyer

Dautriche test

See:velocity of detonation

davidite

A trigonal mineral, (La,Ce)(Y,U,Fe)(Ti,Fe)20 (O,OH)38 ;
crichtonite group; radioactive; metamict; in high-temperature hydrothermal
veins, pegmatites, and mafic igneous rocks; occurs in all stages of
intergrowth and exsolution with ilmenite and hematite, and is an ore of
uranium. Syn:ferutile

davidsonite

A greenish-yellow variety of beryl.

Davis bit

See:Davis cutter bit

Davis calyx drill

A rotary drill similar to the diamond core drill except that the annular
groove is cut either by a steel chisel or by a plain hollow rod using
chilled shot. When the core is of sufficient length to be withdrawn, some
grit is added to the mud flush, which becomes wedged tightly between the
core and base of the barrel. When the rods are raised the core is broken
off and brought to the surface. Nelson

Davis cutter bit

An annular-shaped, sawtoothlike bit used on shot drills to cut core in
soft formations in which shot is ineffective as a cutting medium.
Syn:Davis bit

Davis furnace

A long, one-hearth reverberatory furnace, heated by lateral fireplaces for
roasting sulfide ore. Fay

Davis magnetic tester

An instrument for testing the magnetic content of ores and for checking
the efficiency of wet magnetic separators recovering magnetite and
ferrosilicon in heavy-media processes. Nelson

davisonite

A mixture of crandallite and an apatite. Syn:dennisonite

Davis wheel

A railway tire consisting of a soft plate and boss, and a wear- resistant
tread of water-toughened manganese steel, cast integrally within.
Osborne

davreuxite

A monoclinic mineral, MnAl6 Si4 O17 (OH)2 .

Davy lamp

A safety lamp invented by Sir Humphrey Davy in 1815 for the protection of
coal miners. Its safety feature consisted of a fine-wire gauze enclosing
the flame to keep it from coming in contact with mine gas.
See also:flame safety lamp; safety lamp. Fay

davyne

A hexagonal mineral, (Na,Ca,K)8 Al6 Si6 O24
(Cl,SO4 ,CO3 )2 ; cancrinite group; vitreous to
pearly. Also spelled davina.

dawsonite

An orthorhombic mineral, NaAl(CO3 )(OH)2 ; white; forms thin
incrustations of radiating bladed crystals.

day

a. A term used to signify the surface; e.g., driven to day, meaning to
daylight, therefore to the surface.
b. Wales. The surface of the ground over a mine.
c. In mining, generally a period of 8 h for work on the three-shift
system, or 24 h if referring to the output or to machinery. CTD

day box

See:powder chest

day coal

The topmost stratum of coal; so called from its being nearest to daylight.
Standard, 2

daylight

a. When an underground mine working meets the surface it is said to
daylight. Long
b. The maximum clear distance between the pressing surfaces of a hydraulic
press with the surfaces in their usable open position. Where a bolster is
supplied, it shall be considered the pressing surface. ASM, 1

dc (direct chill) casting

A continuous method of making ingots or billets for sheet or extrusion by
pouring the metal into a short mold. The base of the mold is a platform
that is gradually lowered while the metal solidifies, the frozen shell of
metal acting as a retainer for the liquid metal below the wall of the
mold. The ingot is usually cooled by the impingement of water directly on
the mold or on the walls of the solid metal as it is lowered. The length
of the ingot is limited by the depth to which the platform can be lowered;
therefore, it is often called semicontinuous casting. ASM, 1

deactivation

In froth flotation, treatment of one or more species of mineral particles
to reduce their tendency to float.

dead

a. Said of a mine, vein, or piece of ground that is unproductive.
b. Said of coal that is under no pressure, does not warp and burst, and
makes no sound. CF:alive
c. In economic geology, said of an economically valueless area, in
contrast to a quick area or ore; barren ground. AGI

dead air

a. Stagnant air. BS, 8
b. The air of a mine when it contains carbonic acid gas (blackdamp), or
when ventilation is sluggish. Fay

dead band

In flotation, the range through which an input can be varied without
initiating response. Fuerstenau

dead bed

Unproductive stratum or vein as opposed to bearing or quick bed.
Syn:dead vein

dead-burned

a. The state of a basic refractory material resulting from a heat
treatment that yields a product resistant to atmospheric hydration or
recombination with carbon dioxide. ASTM
b. Completely calcined. AISI

dead-burned dolomite

A refractory product, CaO.MgO, produced by calcination of dolomite or
dolomitic limestone. AGI

dead-burned magnesia

A sintered product consisting mainly of magnesia in the form of dense,
weather-stable refractory granules.

dead burnt

Calcination of limestone, dolomite, or magnesite to the point where
associated clay vitrifies and reduces slaking quality. Pryor, 1

dead chert

See:chalky chert

dead end

a. An entry, gangway, level, or other mine passage extending beyond the
mine workings into solid coal or ore; a stub. Syn:stub entry
b. Underground passageway either blocked or not holed through.
Pryor, 3
c. The unworked end of a drift or working. Hess
d. An unventilated underground mine passage extending some distance beyond
other mine workings into solid rock. Long
e. A term used in coal mining for the termination of all electric wiring
(except cables to equipment) outby the last crosscut where ample
ventilation will reduce the possibility of an electric arc causing an
explosion. Kentucky
f. The end of a drilling line or cable made fast to some stationary part
of the drill rig or to a deadman. Long

dead ground

a. Rock in a mine that, although producing no ore, requires removal in
order to get to productive ground.
b. In mining subsidence, ground that has settled and no further movement
is expected. Nelson
c. Portions of ore deposit too low in value to repay exploitation.
CF:barren ground

deadhead

a. To return to the commencement of a cut without excavating; usually for
the commencement of a new cut after completion of its predecessor.
Austin
b. An extra length given to a cast object, as a cannon, to put pressure on
the molten metal below so that dross and gases may rise into it; a sullage
piece; a sinking head. Standard, 2
c. That part of a casting filling up the ingate; a sprue.
Standard, 2
d. Can. Logs forced into the bottom of a waterway during timber drives.
Hoffman

deadheading

Traveling without load, except from the dumping area to the loading point.
Nichols, 1

dead hole

a. One that extends into solid coal beyond the part that can be broken by
the maximum safe charge of explosive. Zern
b. A shothole so placed that its width at the point (toe), measured at
right angles to the drill hole, is so great that the heel is not strong
enough to at least balance the resistance at the point (toe). Zern
c. A shallow hole in an iron casting. Standard, 2

deadline

a. A row of marked empty powder kegs or other danger signal placed by the
fireboss to warn miners not to enter workings containing gas. Fay
b. The part of a block-and-tackle cable from the traveling block to the
deadline anchor. Long

deadline anchor

The fixed point on a drill rig or deadman to which a deadline of a block
and tackle is attached. Long

dead load

The downward pressure on a structure caused by gravity only, such as the
weight of a long string of drill rods suspended from the sheave in a drill
derrick. Syn:static load

dead lode

A lode not containing valuable minerals in paying quantity. Fay

deadman

a. A wooden block used to guard the mouth of a mine against runaway cars.
Fay
b. A buried log, timber, concrete block, or the like serving as an anchor
to which a pulling line can be attached. Long

dead pressing

Desensitizing of an explosive, caused by excessive pressure or high
density.

dead quartz

Quartz carrying no valuable mineral.

dead rent

Of a mineral lease, the rent that must be paid whether or not minerals are
being extracted. Pryor, 3

dead roast

a. A roasting process for complete elimination of sulfur or other
volatiles. Syn:sweet roast
b. In fluidization roasting, restriction of entering air to permit
oxidation of sulfides, while not allowing process to proceed to any marked
degree of sulfate roasting. Pryor, 3

dead roasting

Sulfide ores are dead roasted when all the sulfur possible to drive off by
roasting has been eliminated. Weed, 2

dead rock

The material removed in the opening of a mine that is of no value for
milling purposes. Waste rock.

dead soft

The state of metal that has been fully annealed. Light Metal Age

dead steel

a. Fully killed steel, which sinks quietly in the ingot mold during
solidification.
b. Steel that fails to respond to heat treatment because it has been
worked at excessively high temperatures; e.g., 1,300 to 1,350 degrees C.
Osborne

dead time

In flotation, the interval of time between initiation of an input and the
start of the resulting response. It may be qualified as effective if
extended to the start of the buildup time, theoretical if the dead band is
negligible, and apparent if it includes the time spent with an appreciable
dead band. Fuerstenau

dead true

A core barrel or drill rod that does not oscillate or vibrate when rotated
at high speed is said to be dead true. Long

dead vein

See:dead bed

dead veins

Veins barren of economic minerals.

deadweight

a. The weight of a vehicle or carrier itself as distinguished from carried
or live load. Crispin
b. The difference, in tons, between a ship's displacement at load draft
and light draft. It comprises cargo, bunkers, stores, fresh water, etc.
CTD

dead work

a. Work that is not directly productive--the removal of rock, debris, or
other material that is not directly productive of coal--though it may be
necessary for exploration and future production. Unfinished work.
See also:stonework
b. Unproductive or stone work; the handling of stone or dirt as a
preliminary step to winning and working the coal seam. The aim is to keep
the dead work per yard of face or ton of coal to the minimum practicable
figure. See also:unproductive development
c. Any kind of miner's work other than actual coal getting and transport.
Mason d. Exploratory or preparatory work, such as cleaning falls of roof,
removing rock, etc., during which little or no coal is secured.
Hudson
e. The development of a mine when no ore is being raised. Gordon
f. Work done by a contractor not provided for in the yardage or tonnage
contract rates. Mason
g. S. Afr. Necessary work to reach and exploit the valuable portions of
the mine. Shaft sinking, crosscutting, driving of levels, etc., belong to
dead work. Beerman

dead zone

That part of the mined strata that has completely settled down after
subsidence. Briggs

dealer

An operator on the stock exchange who buys and sells on his or her own
account and who makes a profit from differences in prices rather than from
commissions. Hoover

debacle

a. A breakup on a river, esp. on the great rivers of the former U.S.S.R.
and of North America. AGI
b. The rush of water, broken ice, and debris in a stream immediately
following a breakup. Syn:ice run
c. Any sudden, violent, destructive flood, deluge, or rush of water that
breaks down opposing barriers and sweeps before it debris of all
kinds.---Etymol: French debacle. AGI

Deblanchol rotary furnace

A cylindrical refractory-lined shell, provided with a gas flue leading to
a recuperator at one end, and a fuel and air port at the other. Air for
combustion is preheated in the recuperator, and oil firing is adopted. The
furnace may be used for melting gray iron and nonferrous metals.
Osborne

debris

Any surficial accumulation of loose material detached from rock masses by
chemical and mechanical means, as by decay and disintegration. It consists
of rock fragments, soil material, and sometimes organic matter. The term
is often used synonymously with detritus, although debris has a broader
connotation. Etymol: French debris. Pl: debris. Syn:rock waste
AGI

debris bag

A dirt-filled bag used for pack walls and chocks. See also:sandbag
Nelson

debris cone

See:alluvial cone

debris deposits

Refuse from hydraulic mining operations, tailings.

decalescence

A phenomenon associated with the transformation of alpha iron to gamma
iron on the heating (superheating) of iron or steel, revealed by the
darkening of the metal surface owing to the sudden decrease in temperature
caused by the fast absorption of the latent heat of transformation.
Syn:point of decalescence

decalescence point

See:critical point

decantation

The settlement of a solid from a liquid, and removal of the clear liquid.

decanter

a. An apparatus for sorting and classifying tailings from gold-washing
operations.
b. A vessel used to decant or to receive decanted liquids.
Webster 3rd

decarbonation

The process of driving off carbon dioxide from a carbonate mineral, e.g.,
magesite, MgCO3 , to form periclase, MgO .

decarburization

The loss of carbon from the surface of a ferrous alloy as a result of
heating in a medium that reacts with the carbon at the surface.
ASM, 1

decay

The general disaggregation of rocks; it includes the effects of both the
chemical and mechanical agents of weathering with, however, a stress on
the chemical effects. Stokes

decay distance

The distance between an area of wave generation and a point of passage of
the resulting waves outside the area. Hy

dechenite

Natural PbV2 O6 ; not established as a valid mineral
species.

decibar

The pressure exerted per square centimeter by a column of sea water 1 m
tall is approx. 1 decibar. The depth in meters and the pressure in
decibars, therefore, are expressed by nearly the same numerical value.
Hy

decibel

The unit for measuring sound intensity. Crispin

decision function

Rule made to control a specific sampling investigation, which defines the
point at which no further observations are to be made, and the nature of
the decision that is to be agreed upon. In a series of sampling
operations, each successive decision function depends on those that have
preceded it. Pryor, 3

deck

a. One of the separate compartments or platforms into which a cage is
divided to hold cars. See also:multideck cage
b. The surface of a concentrating table. Nelson
c. The refractory top of a car used in a tunnel kiln or bogie kiln.
Dodd

deck charge

a. A charge that is divided into several separate components along a
quarry borehole. CF:columnar charge
b. A charge separated by stemming. Carson, 1

decke

See:nappe

decking

a. The operation of changing the tubs on a cage at top and bottom of a
shaft. Also called caging. Fay
b. Separating charges of explosives by inert material and placing a primer
in each charge. Nichols, 1

decking level

The level at which a cage comes to rest at the pit head and pit bottom for
unloading and loading mine cars. Nelson

deck load

A charge of dynamite spaced well apart in a borehole and fired by separate
primers or by a detonating cord. Nichols, 1

deck loading

A method of loading blast holes in which the explosive charges, called
decks or deck charges, in the same hole are separated by stemming, air
cushion, or a plug. Atlas

deck screens

Two or more screens, usually of the vibrating type, placed one above the
other for successive processing of the same run of material.
Nichols, 1

declaratory statement

In practical mining operations, a term applied to the statutory
certificate of location, and a certificate or statement of the location,
containing a description of the mining claim, verified by the oath of the
locator, performing, when recorded, a permanent function. It is the
beginning of the locator's paper title, is the first muniment of such
title, and is constructive notice to all the world. Ricketts

declared efficiency

The efficiency assigned by the maker under certain specified conditions.
Nelson

declination

a. The horizontal angle in any given location between true north and
magnetic north; it is one of the magnetic elements. Syn:variation;
magnetic variation. AGI
b. Angular elevation of a star above celestial equator when truly north of
observer. Pryor, 3
c. Angular deviation of magnetic compass from true north, observed in
conditions where no local deviation affects it. Pryor, 3
d. The angular change in the course of a borehole induced by deflection
techniques, usually expressed in degrees. Long
e. Sometimes a syn. for inclination. See also:inclination

declination maps

Maps on which isogonic lines are shown. Mason

declining conveyor

A conveyor transporting down a slope. See also:retarding conveyor

decollement

Detachment structure of strata owing to deformation, resulting in
independent styles of deformation in the rocks above and below. It is
associated with folding and with overthrusting. Etymol: French,
unsticking, detachment. CF:disharmonic folding
AGI

decomposing furnace

A furnace used in the conversion of common salt into sulfate of soda,
aided by the action of sulfuric acid.

decomposition

See:chemical weathering

decompression

The process of reducing high air pressure gradually enough so as not to
injure people who have been working in it. Nichols, 1

decompression illness

A condition among underwater workers and mine rescue teams that is caused
by ascending too quickly from deep dives.

decompression sickness

See:aeroembolism

decorative stone

a. A term sometimes used alternately with ornamental stone.
b. Natural material used as architectural trimmings in columns,
fireplaces, and store fronts; may be set in silver- or gold-filled
jewelry, as curio stones; e.g., malachite and marble. CF:gemstone

decoupling

A method for decreasing the ground motion generated by an underground
explosion. The method involves the firing of the explosive in the center
of an underground cavity so that the surrounding medium is not in close
proximity to the explosive. Lyman

decrepitate

a. To roast or calcine (as salt) so as to cause crackling or until
crackling stops. Webster 3rd
b. A mineral is said to decrepitate when it flies to pieces with a
crackling noise on being heated. Hess

decrepitation

a. Method of differential disintegration of closely sized mineral, part of
which explodes and is separable by finer screening. Pryor, 3
b. The breaking up with a crackling noise of mineral substances upon
exposure to heat, as when rock salt is thrown into fire.
c. An obsolete method of tunneling, called fire setting.

decussate texture

A microtexture in metamorphosed rocks, in which axes of contiguous
crystals lie in diverse, crisscross directions that are not random but
rather are part of a definite mechanical expedient for minimizing internal
stress. It is most noticeable in rocks composed largely of minerals with a
flaky or columnar habit. AGI

dedolomitization

a. A process resulting from metamorphism, wherein part or all of the
magnesium in a dolomite or dolomitic limestone is used for the formation
of magnesium oxides, hydroxides, and silicates (e.g., brucite, forsterite)
and resulting in an enrichment in calcite. AGI
b. Diagenetic or weathering processes wherein dolomite is replaced by
calcite.

dedusting

A cleaning process in which dust and other fine impurities are removed.
Dedusting is accomplished both by pneumatic means and by dry screening.
Syn:aspirating

deenergize

To disconnect any circuit or device from the source of power. NCB

deep

a. Workings below the level of the pit bottom or main levels extending
therefrom.
b. Forest of Dean; Lanc. A vein, seam, mine, or bed of coal or ironstone.
c. Term used to designate ocean bottom depressions of great depth, usually
deeper than 6,000 m. Hy

deep cell count

A method for examining the mineral particle content of drilling water. In
this method, a glass cell is filled with the water, a little acid is
added, and the sample is placed under a microscope. Dark ground
illumination is used, which shows up the suspended particles. The number
of these is counted, and this number, multiplied by a factor, gives the
number of particles per cubic centimeter. Higham

deep coal

Eng. Coal seams lying at a depth of 1,800 ft (549 m) or more below the
surface. Fay

deep drawing

The process of cold working or drawing a sheet of strip metal, by means of
dies, into shapes involving considerable plastic distortion of the metal;
e.g., automobile mudguards, electrical fittings, etc. CTD

deep hole

In continuous wire-line core drilling, a term applied to boreholes 3,000
ft (915 m) or more in depth.

deep-hole blasting

Blasting a quarry or opencast face by using small- or medium-diameter
holes drilled from top to bottom of the face. Nelson

deep lead

Alluvial deposit of gold or tin stone buried below a considerable
thickness of soil or rock. CF:lead

deep level

a. Trans. The first mining properties developed from the surface were
stopped from trespassing beyond their side lines projected downward. The
next mine on the dip of the lode became known as the "deep-level" mine or
"deep."
b. S. Afr. The distinction of deep level and ultradeep level is a vague
one, and has changed with the times. Ultradeep is now a mining level at a
vertical depth of 9,000 ft ( 2.7 km) and over. Beerman

deep mining

The exploitation of coal or mineral deposits by underground mining
methods. "Deep" is often interpreted as meaning 5,000 ft (1.5 km) or more,
where stresses are high enough to cause sloughing of development openings,
not to mention walls and faces in stopes. However, tectonic horizontal
stresses are greater than gravitational force in many areas. Hence deep
conditions can exist at lesser depths. Indeed, severe rock bursting caused
the closure of a Canadian mine operating at depths of 500 to 700 ft (152
to 213 m). Also, rocks with low strength will produce deep failure
patterns at modest depths, e.g., in Saskatchewan potash mines.
Nelson

deep placer

A sandy or gravelly bed or bottom of an ancient stream covered by lava.

deep scattering layer

Applied to widespread strata in the ocean that scatter or return
vertically directed sound as in echo depth sounding. These layers, which
are evidently of biological origin, are located at depths ranging from 150
to 200 fathoms (274 to 366 m) during the day, with most of them migrating
to or near the surface during the night. Abbrev: dsl. Hy

deep seated

See:plutonic

deep-seated deposit

An ore deposit formed at an estimated depth of 12,000 ft (3.66 km) or
more, at temperatures ranging from 300 to 575 degrees C; e.g., the tin
deposits of Cornwall, England. The deposits are commonly tubular or
veinlike in form, though some are irregular in shape. Lewis

deep-sea terrace

The benchlike feature bordering an elevation of the deep-sea floor at
depths greater than 300 fathoms (1,800 ft or 549 m).
Schieferdecker

deepside

The working of 5 to 10 yd (4.6 to 9.1 m) of the coal seam on the dip side
of an advance gate. It gives some protection from crush along the rib side
and also accommodates dirt from the gate instead of conveying it to the
surface. See also:self-stowing gate

deep sinker

Aust. A tall drinking glass; also the drink it contains, so called in
fanciful allusion to the shaft of a mine.

deep well

A borehole put down through an upper impervious bed into a lower pervious
one, from which a supply of water is obtained. See also:well
Nelson

deep-well pump

a. Any kind of pump delivering from a well, shaft, or borehole.
BS, 10
b. An electrically driven pump located at the low point in the mine to
discharge the water accumulation to the surface.
c. Consists of a series of centrifugal pump impellers mounted on a single
rotating shaft. The casings are termed bowls and the impellers are of the
axial or mixed-flow type. Available in capacities ranging from 25 to
10,000 gal/min (94.6 to 37,854 L/min). It can be used in wells from 25 to
800 ft (7.6 to 244 m) in depth and from 6 to 24 in (15.2 to 61 cm) in
diameter. Carson, 1

deep-well turbine

A simple type of vertical centrifugal pump having one or more stages or
bowls, which are supported from the motor head on the surface by means of
screwed or flanged column pipe sections, each usually 10 ft (3 m) long.
The line shafting from the motor to the impellers is sectional to
correspond with the column section, and may operate in a sectional
extra-heavy enclosing tube if oil is used as a lubricant, or may be
exposed to the water when the pump is built to be water-lubricated.
Pit and Quarry

deep winding

a. Broadly, shaft winding from depths of about 3,000 ft (915 m) and deeper
(coal mining). In the case of shafts deeper than about 5,000 ft or 1.52 km
(gold and metal mining), two-stage hoisting may be used.
See also:winding
b. Hoisting from depths below 5,000 ft in one lift. Spalding
c. Deep hoisting.

Deerparkian

Middle Lower Devonian. AGI

deficient coal

Ark. Coal more difficult to mine than the standard, and for which the
miners are paid an extra price. Fay

deflagrate

To burn; burst into flame; specif., to burn rapidly with a sudden
evolution of flame and vapor.

deflagrating mixture

An explosively combustible mixture, as one containing niter.
Standard, 2

deflagration

An explosive reaction such as a rapid combustion that moves through an
explosive material at a velocity less than the speed of sound in the
material. Atlas

deflation

The removal of loose dry particles by the wind, as along a sand-dune coast
or in a desert; a form of wind erosion. AGI

deflecting plug

a. See:base plug
b. Sometimes used by petroleum drillers as a syn. for deflecting wedge.
Long

deflecting wedge

A class of devices intentionally placed in a borehole to change its
course. All such devices are basically long, tapered, concave metal plugs
that can be set at a predetermined point and bearing in a borehole to
deflect or change its course. Also called correcting wedge, deflecting
plug, deflection wedge, Hall-Rowe wedge, spade-end wedge, Thompson wedge.
See also:correcting wedge; wedge. Long

deflection

A change in the intended course of a borehole produced intentionally or
unintentionally by various conditions encountered in the drill hole or by
the operational characteristics of the drilling equipment used.
Syn:deviation

deflection angle

a. The angular change in the course of a borehole produced accidentally or
intentionally. Long
b. A vertical angle, measured in the vertical plane containing the flight
line, by which the datum of any model in a stereotriangulated strip
departs from the datum of the preceding model. AGI
c. A horizontal angle measured from the forward prolongation of the
preceding line to the following line; the angle between one survey line
and the extension of another survey line that meets it. A deflection angle
to the right is positive; one to the left is negative. AGI

deflection bit

A taper bit, generally a bullnose type, used to drill down past the
deflecting wedge when deflecting a borehole. Long

deflection dial

The load-indicating gage on a penetrometer, which is a soil-testing device
used to determine some of the load-bearing characteristics of silt and
sandy soils. See also:cone penetrator

deflection plug

See:base plug

deflection point

Point of deflection on a refraction time-versus-distance graph separating
two segments that correspond to different wave paths.
Schieferdecker

deflection wedge

A wedge-shaped tool inserted in a borehole to direct the bit along a
prescribed course. Also called whipstock (undesirable usage).
See also:deflecting wedge

deflectometer

An instrument for gaging any deflections of a structure. Hammond

deflector

A device across the path of a conveyor placed at the correct angle to
deflect objects or discharge bulk material. Also called a plow.

deflector sheet

A sheet of brattice or other material erected in a roadway or face to
remove a combustible gases layer. It is usually set at an angle of about
45 degrees from the horizontal and inclined in the direction of airflow.
See also:pocket of gas

deflector-wedge ring

An annular steel ring attached to the upper end of a deflecting wedge,
having a slightly smaller diameter than that of the borehole in which the
wedge is inserted, serving as a stabilizing ring to hold and center the
wedge in the borehole. Also called rose ring. Long

deflocculant

a. Any organic or inorganic material that is used as an electrolyte to
disperse nonmetallic or metallic particles in a liquid, (i.e., basic
materials such as calgonate, sodium silicate, soda ash, etc., are used as
deflocculants in clay slips).
b. A basic material such as sodium carbonate or sodium silicate, used to
deflocculate. Syn:deflocculating agent

deflocculate

a. To disperse a clay suspension so that it has little tendency to settle
and has a low viscosity. ACSG, 2
b. To break up from a flocculated state; to convert into very fine
particles. CF:peptize

deflocculating

a. The thinning of the consistency of a slip by adding a suitable
electrolyte. ASTM
b. The process of making clay slips or suspension using electrolytes or
deflocculants.

deflocculating agent

An agent that prevents fine soil particles or clay particles in suspension
from coalescing to form flocs. Syn:deflocculant; dispersing agent.
ASCE

deflocculation

A state of colloidal suspension in which the individual particles are
separate from one another, this condition being maintained by the
attraction of the particles for the dispersing medium (for example,
hydration) or by the assumption of like electrical charges by the
particles, thus resulting in their mutual repulsion, or both. It is
generally possible to deflocculate a gel to such an extent that it loses
its gel strength entirely, thus becoming a Newtonian fluid, in which case
it is known as a sol. The relative contribution of hydration and
electrostatic repulsion to the deflocculation of a suspension accounts in
large measure for the wide variation in viscosities and gel strengths of
suspensions partially flocculated by different means; as, e.g., a partial
flocculation of drilling fluid by cement on one hand, and by salt water on
the other. Some suspensions can be deflocculated repeatedly by mechanical
agitation alone, thus giving a reversible gel-sol, sol-gel transformation
known as thixotropy. Brantly, 1

deformation

a. A general term for the process of folding, faulting, shearing,
compression, or extension of the rocks as a result of various Earth
forces. AGI
b. See:strain

deformation bands

Parts of a crystal that have rotated differently during deformation to
produce bands of varied orientation within individual grains.
ASM, 1

deformed crossbedding

Crossbedding with foresets overturned or buckled in the down current
direction, usually prior to deposition of the overlying bed. Foreset dip
angle may also be altered by subsequent tectonic folding.
Pettijohn, 1

deformed crystal

A crystal bent or twisted out of its normal shape, so that the angle
between its crystal faces may differ widely from those on the regular
form. See also:distorted crystal

defrother

An agent, e.g., butanol, that destroys or inhibits froth. Pryor, 1

degasification

Progressive loss of gases in a substance leading to the formation of a
more condensed product. Applied primarily to the formation of solid
bitumens from liquid bitumens, but also used in connection with coal
formation. Tomkeieff

degasifier

A substance that can be added to molten metal to remove soluble gases that
might otherwise be occluded or entrapped in the metal during
solidification. ASM, 1

degassing

a. Removing gases from liquids or solids. ASM, 1
b. In pyrometallurgy, addition of deoxidants (phosphorus, aluminum,
silicon, etc.) to remove hydrogen from molten metals before casting.
Pryor, 3

degassing equipment

a. The equipment for extracting gas from an oil-well drilling fluid. The
presence of gas reduces the density of the fluid. Nelson
b. The pumps and equipment used in methane drainage. Nelson

degaussing

Method of demagnetization in which a substance is passed through a coil
that carries alternating current of progressively diminishing strength.
Pryor, 3

degradation

a. The general lowering of the surface of the land by erosion, esp. by the
removal of material through the action of flowing water.
b. Breakage of coal incidental to mining, handling, transport, or storage.
c. The excessive crushing of coal during cutting, loading, and
transportation. All face machines cause degradation, and this has become a
problem at collieries where the market calls for the larger sizes. The
degradation of a coking coal is of lesser importance.
See also:gradation; fragmentation. CF:aggradation
Syn:breakage of coal

degradation screens

Screens used for removing the small sizes, caused by breakage in handling,
from sized coal just before it is loaded for shipment. Degradation
screening is usually necessary where a sized coal is picked, mechanically
cleaned, stored, conveyed, or otherwise handled so that breakage occurs
after it is sized on the main screens. This applies particularly to
domestic coal, which should reach the consumer in as attractive condition
as possible. Mitchell

degraded illite

Illite that has lost much of its potassium as the result of prolonged
leaching. AGI

degreasing

Removal of oil and grease films from metal surfaces before electroplating,
galvanizing, or enameling. Pryor, 3

degreasing machine

An electrically driven machine including high-pressure pump and special
cleaning solution for removing grease and oil from underground mine
machines as a prevention of mine fires.

degree of compaction

The degree of compaction of a soil sample. Hammond

degree of consolidation

The ratio, expressed as a percentage, of the amount of consolidation at a
given time within a soil mass, to the total amount of consolidation
obtainable under a given stress condition. ASCE

degree of liberation

In mineral dressing, the degree of liberation of a certain mineral or
phase is the percentage of that mineral or phase occurring as free
particles in relation to the total of that mineral occurring in the free
and locked forms. Gaudin, 1

degree of locking

In mineral dressing, the degree of locking of a mineral is the percentage
occurring in locked particles in relation to the total occurring in the
free and locked forms. Gaudin, 1

degree of packing

Of an explosive, the loading weight per unit of nominal volume, which is
always known. Its unit is kilogram per cubic decimeter. The degree of
packing defined in this way is 6% greater than the density of the
explosive in the drill hole. Langefors

degree of saturation

a. The percentage of the volume of water-filled voids to the total volume
of voids in a soil. Nelson
b. Ratio of weights of water vapor in air at given conditions and at
saturation, with temperature constant. Specific humidities are usually
employed. Measured in percent. Hartman, 1

degree of size reduction

Ratio of the surface areas or sizes of the broken or crushed material to
those of the feed material. BS, 5

degree of sorting

a. The measure for the spread of grain-size distribution.
Schieferdecker
b. A measure of the spread or range of variation of the particle-size
distribution in a sediment. It is defined statistically as the extent to
which the particles are dispersed on either side of the average; the wider
the spread, the poorer the sorting. It may be expressed by sigma phi.
AGI

degrees Kelvin

Absolute temperature on the centigrade scale, or degrees C plus 273.16.
Strock, 2

degrees Rankine

Absolute temperature on the Fahrenheit scale, or degrees F plus 459.6.
Strock, 2

Dehottay process

A variation of the freezing method of shaft sinking, in which liquid
carbon dioxide is pumped into the ground instead of brine.
See also:Oetling freezing method

dehrnite

A hydrous phosphate of calcium, sodium, and potassium; hexagonal;
crystalline crusts and minute crystals; grayish- to greenish-white. The
mineral from Dehrn, Nassau, Germany, is richer in sodium, conforming
nearly to the formula 7CaO.Na2 O.2P2 O5 .H2 O
, whereas the mineral found near Fairfield, UT is described as
14CaO.2(Na,K)2 O.4P2 O5 3(H2 O,CO2 ) .
English

dehumidification

The process of removing moisture from mine air to increase its cooling
capacity--an important factor in environmental health and comfort in deep
mining. See also:dry kata cooling power; effective temperature.
Hartman, 2

dehydrate

a. To render free from water. Webster 3rd
b. The process of driving water from a hydrated mineral, e.g., gypsum,
CaSO4 .2H2 O , to anhydrite, CaSO4 .

dehydrated

Freed from water or lacking water.

dehydrated stone

One from which the normal water content has been evaporated, usually by
natural processes.

dehydrator

A device or material that will remove water from a substance.
See also:dryer

de-ionization

Removal of ions from solution by chemical means. Syn:demineralization
ASM, 1

Deister table

Proprietary type of shaking table used in mineral processing.
Pryor, 3

delaflossite

A trigonal mineral, CuFeO2 ; in the oxidized zone of copper
deposits.

delatorreite

Former name for todorokite.

delatynite

A variety of amber rich in carbon, low in succinic acid, and lacking
sulfur, at Delatyn in the Carpathian Mountains.

delawarite

An aventurine feldspar from Delaware County, PA.; a pearly orthoclase.
Syn:lennilite

delay

A distinct pause of predetermined time between detonation or initiation
pulses, to permit the firing of explosive charges separately.
Atlas

delay action

In blasting, firing of a round of shots in planned sequence so that cut or
relief holes are blown first. Delay-action electric detonators have
largely replaced safety fuses for this purpose, successive shots being
separated by milliseconds. Pryor, 3

delay blasting

The practice of initiating individual explosive decks, boreholes, or rows
of boreholes at predetermined time intervals using delay detonators, as
compared to instantaneous blasting where all holes are fired essentially
simultaneously. Atlas

delay detonator

An electric or nonelectric detonator used to introduce a predetermined
time lapse between the application of a firing signal and detonation.
Dick, 2

delayed filling

Filling in which the mined-out rooms are filled later, generally on a
large scale and when the neighboring sections are already being mined.
Stoces

delayed pillar extraction

A pillar method of working in which the coal pillars are not extracted
until the whole workings have been driven to the boundary. It is sometimes
adopted when a seam a short distance above is worked simultaneously.
Delayed pillar working increases the difficulty of ventilation, and the
amount of deadwork is increased because of the crushing of coal pillars.
Nelson

delayed quench

One in which the material is not quenched immediately on coming from the
solution heat-treat furnace. This allows precipitation to proceed to a
point at which mechanical properties and corrosion resistance are lowered.
Light Metal Age

delay electric blasting cap

An electric blasting cap with a delay element between the priming and
detonating composition to permit firing of explosive charges in sequence
with but one application of the electric current. It detonates about 1 to
2 s after the electric current has passed through the bridge. It is made
in two kinds, first and second delay, and is used in connection with
regular, waterproof, or submarine electric blasting caps for blasting in
tunnels, shafts, etc., where it is desirable to have charges fired in
succession without the necessity of the blaster returning betweeen shots.
Fay

delay element

An explosive train component consisting of a primer, a delay column, and a
relay transfer charge assembled in a single housing to provide a
controlled time delay. Meyer

delay firing

The firing of several shots in sequence, at designed intervals of time,
usually by means of delay detonators, detonating relays, or sequence
switches. BS, 12

delay interval

The nominal period between the firing of successive delay detonators in a
series of shots. BS, 12

delay period

A designation given to a delay detonator to show its relative or absolute
delay time in a given series.

delay rental

A payment, commonly made annually on a per acre basis, to validate a lease
in lieu of drilling. Wheeler, R.R.

delay series

A series or sequence of delay detonators designed to satisfy specific
blasting requirements. There are basically two types; millisecond (MS) and
long period (LP). Atlas

delay tag

A tag, band, or marker on a delay detonator that denotes the delay series,
delay period and/or delay time of the detonator. They are often color
coded for convenience.

delay time

In seismic refraction work, the additional time required to traverse any
raypath over the time that would be required to traverse the horizontal
component at the highest velocity encountered on the raypath, as it refers
to either the source or receiver end of the trajectory.
Syn:intercept time

delessite

A magnesian variety of chamosite.

delfman

Eng. A miner or worker in a stone quarry.

delhayelite

An orthorhombic mineral, (Na,K)10 Ca5 Al6 Si32
O80 (Cl2 ,F2 ,SO4 )3 .18H (sub 2) O ;
forms in laths in a melilite nephelinite lava at Mt. Shaheru, Kivu
Province, Congo.

deliquescent

Capable of becoming liquid by the absorption of moisture from the air;
e.g., calcium chloride crystals. Standard, 2

delivery column

See:rising main

delivery date

The date on which a metal has to be delivered to fulfill the contract
terms. Also called prompt date. Wolff

delivery drift

A drift or adit connected to a shaft from a point on the surface at a
lower level than the shaft top and used as an outlet into which mine pumps
discharge, so reducing the height through which the water must be lifted.
Syn:jackhead

delivery gate

Eng. A road into which a face conveyor delivers the coal. SMRB

delivery table

a. A conveyor that transports material from the discharge of a machine.
b. A table onto which a chute discharges.

dellenite

a. An extrusive rock between rhyolite and dacite in composition, and,
broadly, the extrusive equivalent of granodiorite.
Webster 2nd; Fay
b. See:plagioclase rhyolite
c. A rhyodacite from Dellen Lake, Sweden.

dells

See:dalles

delorenzite

See:tanteuxenite

delphs

York. The working places in ironstone quarries. Nelson

Delprat method

See:overhand stoping

delrioite

A monoclinic mineral, CaSrV2 O6 (OH)2 .3H2 O ;
pale yellow-green microcrystalline efflorescence on sandstone occurring in
Montrose County, CO.

delta iron

The polymorphic form of iron stable between 1,403 degrees F (762 degrees
C) and the melting point (about 1,532 degrees F or 833 degrees C). The
space lattice is the same as that of alpha iron and different from that of
gamma iron. CTD

deltaite

A mixture of crandallite and hydroxylapatite

deluge water system

A method of fire control in which water is sprayed or sprinkled in
sufficient volume to overwhelm the fire and put it out.
Federal Mine Safety

Demag cappel

A rope cappel used in Koepe winding, particularly in Germany. The rope is
led along the side of the eye and secured by a hinged retaining arm lined
with rubber, and then turned around the eye and held in position by
pressure exerted by knee-action links. Nelson

Demag drag-belt shuttle conveyor

Consists of a single length of belting, half the length of a double unit
face, which is shuttled backward and forward along the face by means of
low-type winches at each end of the face, interlocked and fitted with
limit switches. The coal is plowed off the belt at the loader gate onto
the gate conveyor. Sinclair, 5

demagnetize

To disperse, by means of a suitable magnetic field, solids in a dense
medium that have flocculated magnetically.

demand respirator

An atmosphere-supplying respirator that admits respirable gas to the
facepiece only when a negative pressure is created inside the facepiece by
inhalation. ANSI

demantoid

A transparent, green variety of andradite, having a brilliant luster and
used as a gem. Also called Uralian emerald. Dana, 4

demersal

See:benthonic

demidovite

A phosphoriferous variety of chrysocolla from Tagilsk, Perm, Russia.

demineralization

a. Water softening by use of zeolites or resins to remove cations.
Pryor, 3
b. See:de-ionization

demonstrated resources

A term for the sum of measured resources plus indicated resources.
USGS, 2

dempy

A mine or part of a mine that is prone to outbursts and accumulations of
noxious gases. Nelson

demulsification

Breakdown into separate phases of a relatively stable emulsion, by such
means as flocculation with a surface-active agent or removal of an
emulsifying agent. Pryor, 3

demurrage

The detention of a vessel, railroad car, or other vehicle beyond an
allotted time and for which a fee is usually charged.

dendriform

Resembling a tree, descriptive of some minerals. Syn:arborescent;
dendritic.

dendrite

Any mineral forming branching moss-, fern-, or treelike patterns, e.g.,
some native silver and gold. Syn:dendrolite

dendritic

Said of a mineral that has crystallized in a branching pattern.
Syn:arborescent; dendriform.

dendritic and arborescent

A mineral in treelike or mosslike forms; e.g., manganese oxide.
Nelson

dendritic drainage

The pattern of stream drainage in a region underlain by horizontally
bedded rock, in which the valleys extend in many directions without
systematic arrangement and have a dendritic (treelike) arrangement.

dendritic markings

a. Superficial dendrites on rock surfaces, joint faces, or other
fractures, e.g., manganese oxyhydroxides on rock fracture surfaces.
b. Inclusion of a dendrite in another rock or mineral, e.g., chlorite in
silica to form moss agate.

dendrolite

See:dendrite

Denison core barrel

See:Denison sampler

Denison sampler

A large-size, swivel-type double-tube core barrel designed for
soil-testing work to obtain relatively undisturbed corelike samples of
soft rock and/or soil formations. The inner tube is provided with a thin
wall liner and a finger- or basket-type core lifter or core-retaining
device. Also called Denison core barrel. Long

denningite

A tetragonal mineral, (Mn,Zn)Te2 O5 ; colorless to pale
green; forms tetragonal plates and platy masses; at Sonora, Mexico.

dennisonite

A former name for davisonite. See:davisonite

dense

a. Said of a fine-grained, aphanitic igneous rock whose particles average
less than 0.05 to 0.1 mm in diameter, or whose texture is so fine that the
individual particles cannot be recognized by the unaided eye. AGI
b. Said of a rock whose constituent grains are crowded close together. The
rock may be fine or coarse grained. AGI
c. Said of a rock or mineral possessing a relatively high specific
gravity. AGI

dense graded aggregate

Graded mineral aggregate which contains a sufficient number of very small
particles to reduce the void spaces in the compacted aggregates to a
minimum. API, 1

dense liquid

A homogeneous liquid or solution of specific gravity greater than that of
water (e.g., zinc chloride and calcium chloride) that can be used in
industry or in the laboratory to divide coal or other minerals into two
fractions of different specific gravities.

dense-media separation

a. Heavy-media separation, or sink float. Separation of sinking heavy from
light floating mineral particles in fluid of intermediate density.
Abbreviation: DMS. See also:heavy-media separation
b. Separation of relatively light (floats) and heavy (sinks) particles, by
immersion in a bath of intermediate density. This is the dense or heavy
media, a finely ground slurry of appropriate heavy material in water.
Barite, magnetite ferrosilicon, and galena are in principal use.

dense medium

A fluid formed by the artificial suspension in water of heavy particles
(e.g., magnetite, barite, and shale) that can be used in industry or in
the laboratory to divide coal into fractions of different specific
gravities. BS, 5

dense-medium jigging

This method involves two essential features: (1) the circulation in the
jig of a middling of approx. 3/16 in (4.8 mm) or smaller in size, with sp
gr, 1.7 to 2.0--which fills the interstices of the jig bed and in effect
converts the jig into a float-and-sink machine; and (2) the use of a
suction stroke to hold the medium in the bed and prevent its washing over
with the coal. Mitchell

dense-medium process

A process for the washing of coal, in which the desired separation is
effected in a dense medium. BS, 5

dense-medium recovery

The collection, for reuse, of medium solids from dilute medium, usually
understood to include the removal, in whole or in part, of contaminating
fine coal and clay. Syn:medium-solids recovery

dense-medium washer

A machine for cleaning coal and other materials that uses a dense fluid in
which the coal floats and shale sinks. The fluid consists of water
intimately mixed with sand (or finely ground magnetite or even shale) and
agitated to maintain its consistency. The fluid has an effective specific
gravity of 1.3 to 1.9. In general, coal from about 8 in (20.3 cm) down to
1 in (2.54 cm) is washed by dense medium, below 1 in by Baum washer, and
below 0.75 mm (where cleaning is necessary) by froth flotation. Magnetite
as the dense medium solid is preferred as it can be easily recovered by
magnetic separators and also the upper limit of the specific gravity is
higher (up to 2.0). See also:coal-preparation plant; washery.
Nelson

dense noncrystalline tonstein

This type of tonstein consists almost entirely of fine-grained kaolin
groundmass, showing weak aggregate polarization, containing isolated
corroded crystals of kaolinite. Such bands are commonly more than 100 mm
thick and light in color. IHCP

densimeter

An apparatus used to determine the relative density, or specific gravity,
of a dense media.

densiscope

An apparatus to obtain the specific gravity of pearls as an indication,
but not proof, of genuineness (cultured pearls tend to be denser).

densitometer

An instrument for the measurement of the density of an image produced by
light, X-rays, gamma rays, etc., on a photographic plate; used in some
dust-sampling instruments. Nelson

density

a. The mass of a substance per unit volume. Webster 3rd
b. The quality or state of being dense; closeness of texture or
consistency. Webster 3rd
c. The distribution of a quantity (as mass, electricity, or energy) per
unit usually of space (as area, length, or volume). Webster 3rd
d. The ratio of the mass of any volume of a substance to the mass of an
equal volume of a standard substance; water is used as the standard
substance. Long
e. Having the quality of being dense, hard, or compact. Long
f. Weight of a substance in grams per cubic centimeter (at specified
temperature when close accuracy is needed). For liquids and solids, it
equals specific gravity. Density fluids are heavy liquids used in
float-sink tests. Of a particle, the true density is its mass (m) divided
by volume (v) excluding pores; its apparent density is its mass divided by
volume (m/v) including open but excluding closed pores. Of a mass of
particles (powder), the apparent density is mass divided by volume (m/v);
the bulk density mass divided by volume (m/v) under stated freely poured
conditions; and the tap density mass divided by volume (m/v) after
vibrating or tapping under stated conditions. See also:apparent density;
bulk density. Pryor, 3
g. Mass per unit volume. CF:specific gravity
h. Although density is defined as mass per unit volume, the term is
frequently used in place of unit weight in the field of soil mechanics.
See also:unit weight

density contrast

The difference in density of a valuable mineral and the host rock.
Lewis

density current

A current caused by differences in densities, for example, an excess of
evaporation, cooling, or dilution in a restricted basin or an open sea.
Schieferdecker

density logger

An instrument for direct measurement of formation densities in boreholes.
This tool furnishes a log of backscattered gamma radiation, which is a
simple function of formation density. Dobrin

density of dust cloud

The number of ounces of coal dust per cubic foot (or grams per cubic
meter) of space, suspended in the air or gases in a specified zone.
Rice, 2

density of gases

The vapor density of a gas, or its density relative to hydrogen, is the
number of times a volume of the gas is heavier than the same volume of
hydrogen, the volume of both gases being at the same temperature and
pressure. Cooper

density of seams

a. An indication of the spacing of seams in the strata; the seam density
is said to be high if the seams are close together, or low if they are
widely separated. BS, 7
b. The ratio of the sum of the thickness of a number of adjacent seams to
the thickness of an arbitrarily chosen sequence of strata. BS, 7

density ratio

In powder metallurgy, the ratio of the determined density of a compact to
the absolute density of metal of the same composition, usually expressed
as a percentage. ASM, 1

dental excavation

A controlled blasting technique used to minimize damage, in which the
blasting of small, specially designed rounds over partial faces is used in
extremely sensitive situations. SME, 1

dental work

The act or process of filling cracks, crevices, or caverns encountered in
drilling a borehole with cement or grout; also, the cracks, etc., so
filled. Long

denudation

The sum of the processes that result in the wearing down of the surface of
the Earth, including wear by running water, solution, and wind action.

Denver cell

A flotation cell of the subaeration type. Design modifications include
receded-disk, conical-disk, and multibladed impellers, low-pressure air
attachments, and special froth withdrawal arrangements.

Denver jig

Pulsion-suction diaphragm jig for fine material, in which makeup
(hydraulic) water is admitted through a rotary valve adjustable as to the
portion of jigging cycle over which controlled addition is made. Used in
coal preparation for the removal of pyritic sulfur from thickener
underflow material prior to its treatment by froth flotation.
See also:jig

Denver mud

See:bentonite

deoxidation

The process of extracting the oxygen content of a dissolved oxide, or of
removing dissolved oxygen, with the aid of a reducing agent.
Henderson

deoxidize

To remove oxygen by chemical reaction, generally with carbon.
Mersereau, 2

deoxidized copper

Copper from which cuprous oxide has been removed by adding a deoxidizer,
such as phosphorus, to the molten bath. ASM, 1

deoxidizer

A substance that can be added to molten metal to remove either free or
combined oxygen. ASM, 1

deoxidizing

a. The removal of oxygen from molten metals by use of suitable
deoxidizers. ASM, 1
b. Sometimes refers to the removal of undesirable elements other than
oxygen by the introduction of elements or compounds that readily react
with them. ASM, 1
c. In metal finishing, the removal of oxide films from metal surfaces by
chemical or electrochemical reaction. ASM, 1

dependent shot

A charge of explosives in a borehole that depends for its effect upon the
result of one or more previously fired shots.

dephosphorization

Elimination of phosphorus from steel, in basic steelmaking processes.
Accomplished by forming a slag rich in lime. See also:acid process;
basic process; Bessemer process; open-hearth process. CTD

dephosphorizing

Removal of part or all of residual phosphorus from steel in basic
smelting. Pryor, 3

depleted fuel

See:spent fuel

depletion

The act of emptying, reducing, or exhausting, as the depletion of natural
resources. In mining, specif. said of ore reserves.
See also:economic depletion

depletion allowance

A proportion of income derived from mining or oil production that is
considered to be a return of capital not subject to income tax.
AGI

depocenter

An area or site of maximum deposition; the thickest part of any specified
stratigraphic unit in a depositional basin. AGI

deposit

a. Anything laid down. Formerly applied only to matter left by the agency
of water, but now includes mineral matter in any form that is precipitated
by chemical or other agent, as the ores in veins.
b. Mineral deposit or ore deposit is used to designate a natural
occurrence of a useful mineral, or an ore, in sufficient extent and degree
of concentration to invite exploitation.
c. Earth material of any type, either consolidated or unconsolidated, that
has accumulated by some natural process or agent. The term originally
applied to material left by water, but it has been broadened to include
matter accumulated by wind, ice, volcanoes, and other agents.
CF:sediment
d. An informal term for an accumulation of ore or other valuable earth
material of any origin. AGI
e. Verb. To lay down or let drop by a natural process; to become
precipitated. AGI

deposition

a. The process of natural accumulation of rock material thrown down or
collected in strata by water, wind, or volcanic action; also, the material
thus deposited. Opposite of denudation. Standard, 2
b. The precipitation of mineral matter from solution, as the deposition of
agate, vein quartz, etc. Fay

deposit type

A class representing all the recognized mineral deposits that are defined
by physical and genetic factors that can be consistently differentiated
from those of other classes or deposit types. Barton

depressant

In the froth flotation process, a reagent that reacts with a particle
surface to render it less prone to stay in the froth, thus causing it to
wet down as a tailing product. Depressants act by complexing elements at
surface lattices of minerals that might carry a charge attractive to
conditioning agents; by destroying collector coating; by surface
modification of particles. See also:bathotonic reagent;
surface activity. Pryor, 3

depressed water level

The lowest level of ground water during drainage or pumping.
BS, 10

depression

a. Any relatively sunken part of the Earth's surface; esp. a low-lying
area surrounded by higher ground and having no natural outlet for surface
drainage, as an interior basin or a karstic sinkhole. AGI
b. A structurally low area in the crust, produced by negative movements
that sink or downthrust the rocks. CF:basin; uplift. AGI

depression contour

A closed contour, inside of which the ground or geologic structure is at a
lower elevation than that outside, and distinguished on a map from other
contour lines by hachures marked on the downslope or downdip side.
AGI

depressor

A substance (usually inorganic) that inhibits flotation of the mineral.
CF:activator

depth

S. Afr. The word alone generally denotes vertical depth below the surface.
In the case of incline shafts and boreholes, it may mean the distance
reached from the beginning of the shaft or hole, the borehole depth, or
inclined depth. Beerman

depth contour

See:isobath

depth indicator

A dial or other appliance on a winding apparatus that indicates to the
person in charge the position of the cage in the shaft. The indicator must
be in addition to any mark on the rope or drum.
See also:visual indicator

depth marker

A small metal tag or wooden block placed in the core box at the bottom of
the core recovered from each run, on which is marked the depth at which
the core was cut in the borehole. Long

depth of cut

The thickness of material removed from the workpiece in a single pass.
ASM, 1

depth of focus

Depth of an earthquake or explosion below the Earth's surface.
Schieferdecker

depth of soil exploration

Soil sampling is usually carried down to include all deposits likely to
have a bearing on the stability of mine structures. Shear tests are made
in each bed below the foundation to a depth of at least 1 - 1/2 times the
breadth of the foundations. See also:site investigation

depth of stratum

The vertical distance from the surface of the Earth to a stratum.
AGI

depth per bit

The length of borehole that can be drilled with a steel bit until it must
be resharpened. Streefkerk

depth point

In seismic work, a position at which a depth determination of a mapped
horizon has been calculated. AGI

deputy

a. An underground official in a mine of coal, stratified ironstone, shale,
or fire clay, with statutory responsibility for the safe and proper
working of a district of the mine. Also called examiner; fireman
(undesirable usage). See also:fireman
b. Within limits, the deputy is also in charge of the workers in the
district. Nelson
c. Eng. In Northumberland and Durham, the person who sets timbers or props
in a coal mine is sometimes called a deputy. Nelson
d. N. of Eng. A junior official responsible for safety precautions and
mining operations in a face district. Trist
e. N. of Eng. A person who fixes and withdraws the timber supporting the
roof of a mine, attends to the safety of the roof and sides, builds
stopping, puts up bratticing, and looks after the safety of the miners.
Fay
f. Eng. In the Midland coalfield, an underground official who looks after
the general safety of a certain number of stalls (rooms) or of a district,
the deputy does not set timber but verifies that it is properly done.
Fay
g. A mine boss. Fay

deputy surveyor

A person appointed by the Surveyor General of the United States to make
proper surveys of lode or placer mining claims, prior to the issuing of a
patent. Fay

derail

A safety device for derailing mine cars, usually installed on grades to
protect miners working below. See also:drop log

derailing drag

See:backstay

derail unit

This device locks to rails to derail cars. Wedge construction eliminates
spiking. It protects workers in railroads and mines against wild cars,
switching cars, or sudden car movement. Some types are equipped with a
warning flag. Best, 1

derbylite

A monoclinic mineral, (Fe,Ti)7 SbO13 (OH) ; forms minute
prismatic crystals or twins.

Derbyshire spar

Fluorite, found abundantly in Derbyshire, England. See also:fluorspar
Syn:Derby spar

Derby spar

A popular name for fluorite in Derbyshire, England.
Syn:Derbyshire spar

derbystone

An amethyst-colored variety of fluorite.

derivative rock

A rock composed of materials derived from the weathering of older rocks; a
sedimentary rock, or a rock formed of material that has not been in a
state of fusion immediately before its accumulation. AGI

derivative structure

Representation of crystal structures in terms of a master structure, e.g.,
feldspar as derivative of coesite with aluminum replacing tetrahedral
silicon and charge balance maintained by intertetrahedral alkali and
alkali-earth ions.

derived fossil

A fossil that is not native to the rock in which it is found, e.g., a
fossil found as a pebble in a conglomerate.

derived fuel

A fuel obtained from a raw fuel by some process of preparation for use,
for example, coke, charcoal, benzene, and gasoline. Nelson

dermatitis

A skin disease caused by the application of dust or liquids. In coal
mining, the dusts may be coal or stone dust and the liquids may be mine
waters, oil or grease, perspiration and acids or alkalis. The majority of
cases occur in deep and hot mines having high wet-bulb temperatures.
Mason

derrick

a. The framed wood or steel tower placed over a borehole to support the
drilling tools for hoisting and pulling drill rods, casing, or pipe.
Sometimes incorrectly called a tower. Long
b. The framework over a borehole, used primarily to allow lengths of drill
rod to be added to the drilling column. BS, 9
c. A three- (or more) legged framework for supporting drill rods and
tackle in deep boring; a temporary three-legged headframe, or headgear,
for a shaft. Mason

derrick crane

A crane in which the top of the post is supported by fixed stays in the
rear and the jib is pivoted like the boom of a derrick.
See also:derricking jib crane

derricking jib crane

A jib crane in which the inclination of the jib, and hence the radius of
action, can be varied by shortening or lengthening the tie ropes between
the post and the jib. CTD

derrick rope

The rope used for supporting and hoisting the boom on jib cranes and
excavators. Hammond

desalting

Any process for making potable water from sea water or other saline
waters. Distillation is the oldest method. Others involve electrodialysis,
freezing, extraction, and ion exchange. Also called desalination.

descensional ventilation

A ventilation system in which the downcast air is conducted to the top end
of the workings (in inclined workings) and it then flows downhill from
level to level. In deep mines, the system helps to keep the faces cool.
See also:ascensional ventilation; homotropal ventilation;
antitropal ventilation.

descension theory

A theory of formation of supergene mineral deposits involving the descent
from above of mineral-bearing solutions. The theory originated with the
Neptunian school of thought of the 18th century, which postulated an
aqueous origin for all rocks. CF:ascension theory

descloizite

a. An orthorhombic mineral, 4[PbZn(VO4 )(OH)] having Zn replaced by
Cu toward mottramite; greasy; varicolored; in oxidized zones of ore
deposits; a source of vanadium. Syn:vanadite
b. The mineral group arsendescloizite, cechite, descloizite, mottramite,
and pyrobelonite.

descriptive gemology

The classification, composition, properties, trade grades, sources, and
the methods of recovery, fashioning, and use of gem minerals and gem
materials and their substitutes. See also:gemology

descriptive mineralogy

That branch of mineralogy devoted to the description of the physical and
chemical properties of minerals. Fay

deseaming

Removal by chipping of surface blemishes from ingots or blooms.
Pryor, 3

desert crust

a. A hard layer, containing calcium carbonate, gypsum, or other binding
matter, exposed at the surface in a desert region. AGI
b. Desert varnish. AGI
c. Desert pavement. AGI

desert glass

See:obsidian; moldavite.

desert lands

All lands exclusive of timber lands and mineral lands that will not,
without irrigation, produce some agricultural crop. Ricketts

desert pavement

A natural residual concentration of wind-polished pebbles, boulders, and
other rock fragments, mantling a desert surface where wind action and
sheetwash have removed all smaller particles, and usually protecting the
underlying finer-grained material from further deflation. The fragments
commonly are cemented by mineral matter. Syn:desert crust
See also:lag gravel

desert rat

In the Western United States, a prospector, esp. one who works and lives
in the desert, or who has spent much time in arid regions. The name is
derived from a small rodent common throughout much of the Great Basin and
Southwestern United States. Fay

desert rose

A radially symmetrical group of crystals with a fancied resemblance to a
rose, formed in sand, soft sandstone, or clay. These crystals are commonly
calcite, less commonly barite, gypsum, or celestine.

desert varnish

A thin dark shiny film or coating, composed of iron oxide accompanied by
traces of manganese oxide and silica, formed on the surfaces of pebbles,
boulders, and other rock fragments in desert regions after long exposure,
as well as on ledges and other rock outcrops. It is believed to be caused
by exudation of mineralized solutions from within and deposition by
evaporation on the surface. See also:patina

desiccant

A substance having an affinity for water. Used for drying purposes.
Bennett

desiccate

To dry; to remove moisture; to preserve by drying. Webster 3rd

desiccation

A drying out, as in loss of water from sediments, or evaporation from
water bodies in arid regions, producing evaporites.

desiccation crack

See:mud crack

desiccator

A short glass jar fitted with an airtight cover and containing some
desiccating substance (as calcium chloride), above which is placed the
material to be dried or to be protected from moisture. Webster 3rd

design

A type of diamond-drill fitting that, when standardized, has specific
dimensions and thread characteristics establishing interchangeability of
parts made by different manufacturers, and size by specific dimension of
the set core-bit inside diameter. Design characteristics supplement the
group characteristics that provide for integration of ranges. The design
characteristics of drill fittings are established by the second letter in
two-letter names and by the third letter in three-letter names. Letters
denoting design may establish interchangeability of all parts, as in the
M-design core barrel, or only of certain parts, as in the X-design core
barrel. CF:group; range. Long

designated size

The particle size at which it is desired to separate a feed by a sizing
operation. BS, 5

designed borehole deflection

The turning of a borehole along a different course at depth. This may be
achieved, but not without difficulty. The cutting bit is guided upon its
new course by the curved surface of a deflecting wedge that is positioned
with the aid of a modified Oehman instrument. In petroleum drilling, much
use is made of holes that are deflected at a predetermined depth. The
technique is known as whipstocking. Nelson

design horsepower

The specified horsepower multiplied by a service factor. It is the value
used to select the chain size for a chain drive. Jackson, 1

desilication

The removal of silica from a rock or magma by the breakdown of silicates
and the resultant freeing of silica, or by reaction between a body of
magma and the surrounding wall rock. AGI

desiliconizing

A practice of jetting oxygen into pig iron before it is charged into the
steel furnace; this oxidizes and removes most of the silicon.
Newton, 1

desilverization

The process of removing silver (and gold) from lead after softening.
See also:Parkes process; Pattinson process. CTD

desliming

The removal of slimes from coal or a mixture of coal and water, however
accomplished. BS, 5

desliming screen

A screen used for the removal of slimes from larger particles, usually
with the aid of water sprays. BS, 5

deslurrying

Fines removal by wet methods. BS, 5

desmine

A former name for stilbite.

desmite

The amorphous groundmass, which is transparent in thin sections, binding
together the constituents of bituminous coal of high grade. Applies to the
transparent variety of residuum found in high-grade coals.
Tomkeieff

desmosite

A banded adinole. AGI

desorption

The reverse process of adsorption whereby adsorbed matter is removed from
the adsorbent. The term is also used as the reverse process of absorption.

destinezite

See:diabandite

destressed area

a. In strata control, a term used to describe an area where the force is
much less than would be expected after considering the depth and type of
strata. CF:overstressed area
Mason
b. A region of low stress behind the walls of a stoped-out region.
Issacson

destressing

In deep mining, relief of pressure concentrations induced by mining or
caused by geological factors. Performed by drilling and blasting to loosen
the zones of peak stress. The peak load surrounding the excavation walls
is thus transferred deeper into the undisturbed rock, and a protective
barrier is formed. Pryor, 3

destructive distillation

The distillation of solid substances accompanied by their decomposition.
The destructive distillation of coal results in the production of coke,
tar products, ammonia, gas, etc. CTD

destructive testing

Testing methods, the use of which destroy or impair the part or product
insofar as its intended use is concerned, but which give proof or an
indication of the strength or quality of similar or duplicate parts or
products. Such tests involve the subjection of the test piece to various
influences, of destructive magnitude, such as impact, stress, pressure,
cyclic movement, etc. See also:nondestructive testing
Henderson

desulfurization of steel

The removal of a high proportion of sulfur from steel by injection of
calcium or magnesium. Nelson

desulfurize

To free from sulfur; to remove the sulfur from an ore or mineral by some
suitable process, as by roasting.

detachable bit

A drilling bit that is threaded or tapered and is removable from the drill
steel; not formed as an integral part of the drill steel. The all-steel
bit can be resharpened, but the tungsten carbide insert type may be
nonresharpenable. Also known as rip bit or knockoff bit. See also:bit;
hot miller.

detached head pulley

See:head pulley

detaching hook

An appliance that releases automatically the winding rope from the cage
should an overwind occur. See also:wedge guide

detachment

See:decollement

detail drawing

A large-scale drawing showing all small parts, details, dimensions, etc.
Nichols, 1

detailed soil survey

The final soil tests at site as guided by the general soil survey. The
tests may be performed in situ by mobile laboratory units, or the samples
are sent to the nearest soils laboratory. See also:general soil survey;
preliminary soil survey. Nelson

detaline system

A nonelectric system of initiating blasting caps in which the energy is
transmitted through the circuit by means of a low-energy detonating cord.
Dick, 2

detector

a. See:magnetic detector
b. See:seismometer
c. The component of a remote-sensing system that converts electromagnetic
radiation into a signal that can be recorded. See also:pickup
Syn:radiation detector
d. See:sensor

determinative gemology

The science of differentiating (1) between the various gemstones, (2)
between gemstones and their substitutes, and (3) among such substitutes.
See also:gemology

determinative mineralogy

That branch of mineralogy that comprises the measurement of the nature,
composition, and classification of minerals by means of physical tests
(e.g., density, hardness), chemical analyses both qualitative and
quantitative, spectrochemical analyses including both absorption and
emission spectra, electron probe microanalyses, autoradiography, thermal
analyses, optical tests in both transmitted and reflected light, electron
microscopy, diffraction of X-rays or electrons, and crystallographic
analyses.

detinning

Treatment by chlorination of tinbearing scrap for recovery of tin as its
chloride. Pryor, 3

detonate

To cause to explode by the application of sudden force.
Standard, 2

detonating cord

A flexible cord made of wound hemp or jute threads covered with plastic
containing a center core of high explosive (PETN) and used to initiate
other explosives.

detonating fuse

A fuse consisting of high explosive that fires the charge without the
assistance of any other detonator. It consists of a high-explosive core of
pentaerythritol tetranitrate (PETN) enclosed in tape and wrapped with
textile countering yarns. Usually, this fuse is then reinforced or
completely enclosed in a strong waterproof plastic outer cover. The
finished external diameter is normally about 0.2 in (5 mm). Primacord is
the best known brand. See also:Cordtex; safety fuse.
Fay; McAdam, 2; Nichols, 1; Nelson

detonating gas

A gaseous mixture that explodes violently on ignition (as two volumes of
hydrogen with one volume of oxygen, forming water). Webster 2nd

detonating powder

Any powder or solid substance that when heated or struck explodes with
violence and a loud report. Webster 2nd

detonating primer

A name applied for transportation purposes to a device consisting of a
detonator and an additional charge of explosives, assembled as a unit.

detonating rate

The velocity with which the explosion wave travels through the column of
charge. Streefkerk

detonating relays

A device for obtaining short-delay blasting in conjunction with the
detonating fuse. It consists essentially of two open-ended delay
detonators coupled together with flexible neoprene tubing.
McAdam, 2

detonating tube

A eudiometer for making explosions. Webster 2nd

detonation

a. An explosive decomposition or explosive combustion reaction that moves
through the reactant(s) at greater than the speed of sound in the
reactant(s) to produce (1) shock waves and (2) significant overpressure,
regardless of confinement.
b. An extremely rapid explosion; the firing of an explosive charge by fuse
or electric detonator. Nelson
c. The action of converting the chemicals in an explosive charge to gases
at a high pressure, by means of a self-propagating shock wave passing
through the charge. BS, 12

detonation pressure

The pressure produced in the reaction zone of a detonating explosive and
is a function of explosive density and detonation velocity.

detonation traps

Devices that prevent a detonation initiated in one part of a system from
propagating to another. Van Dolah

detonation velocity

a. The velocity at which a detonation progresses through an explosive.
b. See:velocity of detonation

detonator

A device for producing detonation in a high-explosive charge, and
initiated by a safety fuse or by electricity. Syn:percussion cap
See also:blasting cap; electric detonator. BS, 12

detonator case

A container for carrying detonators in mines. It is so constructed that,
when closed, a detonator or the leads of a detonator cannot come into
contact with either the metal of the case or any metal outside the case.
Nelson

detrital

Pertaining to or formed from detritus; said esp. of rocks, minerals, and
sediments. See also:clastic

detrital deposits

Placer or detrital deposits are composed of minerals that have been
released by weathering and later have been transported, sorted, and
collected by natural agencies into valuable deposits. Such minerals are
usually of high specific gravity and are resistant to abrasion and
weathering. Examples are gold, diamonds, platinum, tin (cassiterite),
monazite, magnetite, and ilmenite, these last two being the common
constituents of black sand. Lewis

detrital fan

See:alluvial fan

detrital mineral

Any mineral grain resulting from mechanical disintegration of parent rock;
esp. a heavy mineral found in a sediment or weathered and transported from
a vein or lode and found in a placer or alluvial deposit. AGI

detrital rock

A rock composed primarily of particles or fragments detached from
preexisting rocks either by erosion or by weathering; specif. a
sedimentary rock having more than 50% detrital material.
CF:chemical rock

detritus

A collective term for loose rock and mineral material that is worn off or
removed by mechanical means, as by disintegration or abrasion; esp.
fragmental material, such as sand, silt, and clay, derived from older
rocks and moved from its place of origin. CF:debris

deuteric

Referring to reactions between primary magmatic minerals and the
water-rich solutions that separate from the same body of magma at a late
stage in its cooling history. Syn:epimagmatic
See also:autometamorphism

deuteromorphic

A general term applied to crystals whose shapes have been acquired or
modified by mechanical or chemical processes acting on the original forms.
AGI

De-Vecchis process

A method for the smelting of pyrites that entails the roasting and
magnetic concentration of the raw material followed by reduction in a
rotary kiln or electric furnace. The product may be briquetted and reduced
in the blast furnace, but is better smelted in an electric furnace.
Osborne

develop

a. To open a mine and ore; more or less, to search, prospect, explore.
von Bernewitz
b. To traverse a mineralized body horizontally by drives and vertically by
shafts or winzes to prove its extent. CTD
c. To open up orebodies by shaft sinking, tunneling, or drifting.
Ballard

developed ore

See:developed reserve

developed reserve

Ore that has been exposed on three sides and for which tonnage and quality
estimates have been made; ore essentially ready for mining.
CF:proved reserve
assured mineral. AGI

development

a. The preparation of a mining property or area so that an orebody can be
analyzed and its tonnage and quality estimated. Development is an
intermediate stage between exploration and mining. AGI
b. To open up a coal seam or orebody as by sinking shafts and driving
drifts, as well as installing the requisite equipment. Nelson
c. Work of driving openings to and in a proved orebody to prepare it for
mining and transporting the ore. Lewis
d. The amount of ore in a mine developed or exposed on at least three
sides. CTD
e. S. Afr. The work done in a mine to open up the paying ground or roof
and, in particular, to form drives or haulages around blocks of ore, which
are then included under developed ore reserves. Beerman
f. A geologic term, applied to those progressive changes in fossil genera
and species that have followed one another during the deposition of the
strata of the Earth.
g. In construction of a water well, the removal of fine-grained material
adjacent to a drill hole, enabling water to enter the hole more freely.
AGI
h. Exploitation of ground water. AGI

development drift

a. A main tunnel driven from the surface, or from a point underground, to
gain access to coal or ore for exploitation purposes. Nelson
b. Slant.

development drilling

Delineation of the size, mineral content, and disposition of an orebody by
drilling boreholes. Long

development drivages

The shafts, tunnels, laterals, crosscuts, and staple pits to prove and
render accessible the coal or ore to be extracted.
See also:productive development; unproductive development.
Nelson

development engineer

In bituminous coal mining, one who operates a hoist to raise and lower
workers, rock, and supplies during development work (sinking shafts and
driving horizontal underground passages prior to the actual mining of coal
from a seam). DOT

development miner

See:miner

development plan

A plan showing the proposed development of the mine workings, and kept for
operational purposes. BS, 7

development rock

S. Afr. The rock broken during development work in payable ground, which
contains both valuable and barren rock and is, therefore, included in the
tonnage sent to the reduction plant of a mine. Beerman

development sampling

Sampling for the establishment of reserves and conducted primarily upon
the exposures along the development drivages. See also:reserve
Nelson

development work

Work undertaken to open up orebodies as distinguished from the work of
actual ore extraction. Sometimes development work is distinguished from
exploratory work on the one hand and from stope preparation on the other.
AGI

Devereaux agitator

An upthrust propeller, stirring pulp vigorously in a cylindrical tank, used
in leach agitation of minerals. Pryor, 1

deviate

To change the course of a borehole. CF:walk; wander. Long

deviating

Syn. for deflecting. Long

deviation

a. The departure of a drilled hole from being straight. The hole may be
either vertical or inclined, and the departure may be in any direction.
Deviation may be intentional, as in directional drilling, or undesirable.
Syn:deflection
b. In more general use, the angle of departure of a well bore from the
vertical, without reference to direction. AGI
c. The distance, measured in a horizontal plane, between two surveyed
points in a borehole or between the collar and any point below the collar
in a borehole. Also called dislocation; throw. Long

devilline

A monoclinic mineral, CaCu4 (SO4 )2 (OH)6 .3H
2 O ; emerald-green to verdigris-green. Formerly called devillite;
herrengrundite; lyellite; urvolgyite.

devillite

See:devilline

devil's dice

Cubes of fully or partially oxidized and hydrated pseudomorphs of pyrite
in alluvial workings.

devil's dough

A hard, gray-white siliceous rock. Arkell

devitrification

a. Deferred crystallization, which, in glassy igneous rocks, converts
obsidians and pitchstones into dull cryptocrystalline rocks (commonly
called felsites) consisting of minute grains of quartz and feldspar. Such
devitrified glasses reveal their originally vitreous nature by traces of
perlitic and spherulitic textures.
b. The process by which glassy rocks break down into definite minerals,
which are commonly minute, chiefly quartz and feldspar.
c. Any change from a glassy state to a crystalline state after
solidification.
d. In ceramics, a surface defect manifested by loss of gloss as a result
of crystallization.

devitrify

To destroy the glasslike character of volcanic glasses by changing from
the vitreous state to the crystalline state.

devolatilization

Progressive loss of volatiles by the substance undergoing coalification
process. Tomkeieff

Devonian

The fourth period, in order of decreasing age, of the periods making up
the Paleozoic era. It followed the Silurian period and was succeeded by
the Mississippian period. Also, the system of strata deposited at that
time. Sometimes called the Age of Fishes. Fay

De Vooy's process

The sink-float or dense-media process used for coal cleaning. The
separating fluid is a clay-barite water pulp. Pryor, 3

dewater

To remove water from a mine; an expression used in the industry in place
of the more technically correct word, unwater. Hudson

dewatering

a. The removal of water from a drowned shaft or waterlogged workings by
pumping or drainage as a safety measure or as a preliminary step to
resumption of development in the area. CF:unwatering
b. The draining of an aquifer when adjacent wells or mine workings are
pumped.
c. The mechanical separation of a mixture of coal and water into two
parts, one which is relatively coal-free, the other relatively water-free,
with respect to the original mixture. Mitchell
d. The mechanical separation of solid matter from water in which it is
dispersed, by such equipment as thickeners, classifiers, hydrocyclones,
filters, and centrifuges. Coarser coal sizes may be dewatered by slotted
screens or perforated bucket elevators.
e. The process in which solid material, either submerged or containing
liquid, is conveyed or elevated in a manner that allows the liquid to
drain off while the solid material is in transit.

dewatering classifier

A settling tank for clarifying washer circulating water or for
concentrating gold slimes before cyaniding. The tank may have a
continuously working rake that moves the sludge toward the outlet pipe in
the bottom. See also:dryer

dewatering elevator

Similar to the continuous bucket elevator, it is often used in sand and
gravel plants where the dredge line discharges to a sump. The dewatering
elevator digs the material from the sump, allowing the water to drain out
through perforations in the backs of the buckets while being elevated, and
discharges to the plant for further processing. Pit and Quarry

dewatering screen

A screen used for the separation of water from solids. BS, 5

deweylite

A mixture of a disordered clinochrysotile or lizardite with a talclike
mineral.

dewindtite

An orthorhombic mineral, Pb3 (UO2 )6 H2 (PO
4 )4 O4 .12H2 O ; strongly radioactive; canary
yellow; associated with torbernite and other secondary uranium minerals.

dewpoint

The temperature to which air must be cooled, at constant pressure and
constant water vapor content, in order for saturation to occur. Since the
pressure of the water vapor content of the air becomes the saturation
pressure, the dewpoint may also be defined as the temperature at which the
saturation pressure is the same as the existing vapor pressure. Also
called saturation point. AGI

dewpoint hygrometer

An instrument for determining the dewpoint; a type of hygrometer.
Hunt

dextral fault

See:right-lateral fault

dextrin

A carbohydrate, C6 H18 O5 , hydrolyzed from starch by
dilute acids. Used in flotation as depressant. Pryor, 1

d'Huart reagent

An etching reagent that reveals not only the macrostructure and faults,
such as piping, segregation, particularly sulfur and phosphorus, and
cracks, but also slip lines in mild steel that has been stressed beyond
its elastic limit. Composition is 100 mL of distilled water, 100 mL of
concentrated hydrochloric acid, and 40 g of crystallized chromic acid, 16
g of anhydrous nickel chloride. Osborne

diabandite

A ferroan variety of clinchlore. Syn:destinezite

diabase

In the United States, an intrusive rock whose main components are
labradorite and pyroxene and that is characterized by ophitic texture. As
originally applied by Brongniart in 1807, the term corresponded to what is
now recognized as diorite. The word has come to mean a pre-Tertiary basalt
in Germany, a decomposed basalt in England, and a dike-rock with ophitic
texture in the United States and Canada (Johannsen, 1939). CF:trap
Syn:dolerite

diabasic

Composed of or resembling diabase. AGI

diablastic

Pertaining to a texture in metamorphic rock that consists of intricately
intergrown and interpenetrating constituents, usually with rodlike shapes.
AGI

diachronism

The transgression, across time planes or biozones, by a rock unit whose
age differs from place to place; the state or condition of being
diachronous. AGI

diachronous

Said of a rock unit that is of varying age in different areas or that cuts
across time planes or biozones; e.g., said of a sedimentary formation
related to a narrow depositional environment, such as a marine sand that
was formed during an advance or recession of a shoreline and becomes
younger in the direction in which the sea was moving.
Syn:time-transgressive

diad

An axial rotation of 180 degrees . Syn:twofold

diadochite

A hydrated ferric phosphate and sulfate mineral, brown or yellowish in
color. Fay

diagenesis

Any change occurring within a sediment after its deposition and during and
after its lithification, exclusive of weathering. It includes such
processes as compaction, cementation, replacement, and crystallization,
under normal surficial conditions of pressure and temperature.

diagenetic deposits

Deposits consisting dominantly of minerals crystallized out of sea water,
such as manganese nodules. Hunt

diagnostic mineral

a. A mineral, such as olivine or quartz, whose presence in an igneous rock
indicates whether the rock is undersaturated or oversaturated. There are
also diagnostic minerals in sedimentary and metamorphic rocks.
Syn:symptomatic mineral
b. A mineral whose presence permits certain deductions pertaining to a
geologic history of a rock or sediment.

diagonal fault

See:oblique fault

diagonal joints

a. Joints diagonal to the strike of the cleavage. Zern
b. In igneous rocks, joints that occur at 45 degrees to the flow lines and
are caused by shear. Lewis

diagonal-slip fault

See:oblique-slip fault

dial

a. A compass used for surface and underground surveying. It is fitted with
sights, spirit levels, and a vernier, and mounted on a tripod.
Syn:mining dial
b. Corn. To make a mine survey. Pryor, 3

dialing

a. The process of running an underground traverse with a mining dial. Also
spelled: dialling. CTD
b. Surveying, usually magnetic, using miner's dial. Pryor, 1

diallage

A dark green or bronze-colored monoclinic pyroxene, which in addition to
the prismatic cleavages has others parallel to the vertical pinacoids.
Mohs hardness, 4; sp gr, 3.2 to 3.35. Used also as a prefix to many rocks
containing the mineral. See also:pyroxene
AGI; Webster 3rd; Fay

dialogite

A former name for rhodochrosite.

dialysis

A method of separating compounds in solution or suspension by their
differing rates of diffusion through a semipermeable membrane, some
colloidal particles not moving through at all, some moving slowly, and
others diffusing quite readily. CF:osmosis
See also:electrodialysis

diamagnetic

Having a small, negative magnetic susceptibility. All materials that do
not show paramagnetism or magnetic order are diamagnetic. Typical
diamagnetic minerals are quartz and feldspar. CF:paramagnetic
AGI

diamagnetism

The property of certain substances by virtue of which they are repelled
from both poles of a magnet and tend to set with the longer axis across
the lines of magnetic force. CF:ferrimagnetism; paramagnetism.
Standard, 2

diamantiferous

See:diamondiferous

diametric rectifier circuit

A circuit that employs two or more rectifying elements with a conducting
period of 180 electrical degrees, plus the commutating angle.
Coal Age, 1

diamond

a. An isometric mineral, a form of carbon, C ; crystallizes in octahedra,
dodecahedra, or cubes, commonly with curved edges and striated faces;
rarely twinned; has octahedral cleavage and conchoidal fracture. Fresh
cleavages have adamantine luster, but crystal faces are commonly greasy;
colorless when pure but pale tints to black (bort) with impurities. The
hardest natural substance, it defines 10 on the Mohs hardness scale and 15
on the Povarennykh scale, but ranges from 42 to 46 on a linearized Mohs
scale. Its high refractive index (n = 2.42) and strong dispersion give
fire to faceted gems. Diamond occurs in kimberlite pipes and dikes, also
in river and beach placers. See also:congos
b. A crystalline material resembling diamond such as rock crystal (quartz)
locally known as "Bristol diamond," "Herkimer diamond," "Lemont diamond,"
"Lake George diamond," or "Arkansas diamond."
See also:industrial diamonds; manmade diamond.
c. A pointed wooden or iron arrangement placed between rails, just before
a curve or switch, where tram cars are liable to be derailed, to force
them to remain on the rails. Fay

diamond ballas

An important industrial variety of diamond. The stones are spherical
masses of minute diamond crystals arranged more or less radially. They
have no well-defined cleavage planes and thus have great resistance to
abrasion. While the term, ballas, was first applied to such stones from
Brazil, diamonds of similar structure known as Cape and African ballas are
found. In color, ballas ranges from white to varying shades of black.
While Cape and African ballas are not as hard as the Brazilian, they
include some fine and unusual stones. Production is small. Rarely, if
ever, used for diamond drilling but very valuable for diamond tools.
Cumming, 1

diamond bit

A rotary drilling bit studded with bort-type diamonds. Also called boart
bit; boart-set bit. Syn:bort bit; bort-set bit. AGI; Long

diamond boring

Precision boring with a shaped diamond (but not with other tool
materials). ASM, 1

diamond chip

A thin, tabular chip of an uncut diamond crystal, weighing less than 0.75
carat. AGI

diamond chisel

A cutting chisel having a diamond or V-shaped point. Fay

diamond cleavage

The plane along which a diamond crystal can be split easily. The four
planes paralleling the faces of an octahedron are those generally referred
to as the cleavage planes, or diamond cleavage. All crystalline diamonds
are more or less brittle and will be fractured by a sufficiently violent
blow, but the irregular surface of a fracture cannot be mistaken for the
brilliant flat surface produced by cleaving. The carbon has no cleavage,
and in ballas cleavage is absent or very poorly defined. Long

diamond cleaving

The act or process of splitting diamonds into smaller pieces, which may be
more readily used as tool points, gems, or drill diamonds. Long

diamond concentration

The ratio of the area of a single-layer bit face covered by the inset
diamonds or, in an impregnated bit, the bulk proportion of the crown
occupied by diamonds. Long

diamond content

The number of carats of diamonds inset in the crown of a diamond bit. Also
called stone content; stone weight. Long

diamond core drill

A rotary-type drill machine using equipment and tools designed to recover
rock samples in the form of cylindrical cores from rocks penetrated by
boreholes. See also:core drill; diamond drill. Long

diamond coring

The act or process of obtaining a core sample of rock material using a
diamond-inset annular bit as the cutting tool. This tubular bit and
attached core barrel are rotated at a speed under controlled pressure by
means of hollow steel, flush-jointed rods through which water is pumped to
cool the bit and remove rock cuttings. With the advance of the bit, a
cylindrical core of rock passes up into the core barrel, where it is held
by a core lifter or other device. Long; Cumming, 1

diamond count

a. The number of diamonds set in the crown of a specific diamond bit. Also
called bit count; stone count. Long
b. Sometimes incorrectly used to indicate the average size of the diamonds
inset in a specific bit. See also:carat count

diamond crown

The cutting bit in diamond drilling. It consists of a steel shell
containing small cavities in its face and edges into which black diamonds
are set. In some types of crown the diamonds can be removed and reset for
further use. Grooves, called waterways, are usually provided in the face
of the crown to allow the passage of the drilling fluid. For surface-set
bits in diamond drilling, it is recommended that 2 to 20 stones per carat
should be used in soft ground (such as shale); 10 to 80 stones per carat
in medium ground (such as sandstone); and 20 to 150 stones per carat in
hard ground (such as granite). See also:burned bit

diamond cubic

With respect to atomic arrangements, similar to the diamond in having the
two face-centered cubic arrangements of atom centers either of which is
displaced with respect to the other by one-fourth of the diagonal of the
unit cube. Henderson

diamond cutter

a. An individual skilled in the art of shaping diamonds as gems.
Long
b. A tool in which a single diamond, shaped as a cutting point, is inset.
Long

diamond cutting

One of the three processes by which diamonds are prepared for use as
ornaments or in the arts, the others being diamond cleaving and diamond
polishing. Fay

diamond drill

a. A drilling machine with a rotating, hollow, diamond-studded bit that
cuts a circular channel around a core, which can be recovered to provide a
more or less continuous and complete columnar sample of the rock
penetrated. AGI; Long
b. Diamond drilling, a common method of prospecting for mineral deposits.
Also called adamantine drill; diamond core drill; rotary drill.
See also:core drill; hydraulic circulating system. AGI; Long

diamond-driller helper

One who assists in the erection and operation of a core drill that bores
into rock, earth, and other minerals to obtain core samples. Also called
core-driller helper; core-drill-operator helper;
diamond-point-drill-operator helper; drill-runner helper;
shot-core-drill-operator helper; test-borer helper; test-hole-driller
helper; wash-driller helper. DOT

diamond drilling

The act or process of drilling boreholes using bits inset with diamonds as
the rock-cutting tool. The bits are rotated by various types and sizes of
mechanisms motivated by steam, internal-combustion, hydraulic,
compressed-air, or electric engines or motors. A common method of
prospecting for mineral deposits. See also:diamond drill

diamond-drill sample

The core brought to the surface in the core barrel. The cuttings in the
uprising drilling fluid will also provide sampling material.
Syn:core recovery

diamond dust

a. Finely fragmented or powdered diamonds used as a cutting, grinding, and
polishing abrasive or medium.
b. A diamond powder produced in the cutting of gems.

diamond exposure

The proportional mass of a diamond protruding beyond the surface of a
matrix metal in which the diamond is inset. CF:bit clearance
Syn:stone exposure

diamond grade

The worth of a diamond as based on an individual sorter's interpretation
of somewhat arbitrary standards of color, presence of flaws, soundness,
and shape. Long

diamondiferous

Any substance containing diamonds, generally applied to rock or alluvial
material containing diamonds, but may also refer to diamond-impregnated
substances, such as the crown of a diamond-impregnated drill bit.

diamond impregnated

Having diamonds distributed throughout a matrix. Long

diamond life

The amount of cutting a diamond will accomplish before being completely
worn away by abrasion. In bits, diamond life usually is expressed in the
number of feet drilled in a specific rock before the inset diamonds become
too dulled to continue cutting or are lost by rollout or completely worn
away by abrasion. Long

diamond matrix

a. A metal or metal alloy forming the material in which the diamonds inset
in a bit crown are embedded. Also called bit-crown metal; bit-crown
matrix; bit matrix; crown metal; matrix. Long
b. The rock material in which diamonds are formed naturally and occur,
such as in kimberlite. Long

diamond needle

A small-diameter hollow metal tube attached to a flexible rubber tube
through which air is pulled by a suction or vacuum pump. The suction
created at the tip of the metal tube enables a bit setter to pick up and
place a small diamond in a bit mold with greater facility than with
tweezers. Called a needle because the metal tube generally is made by
using a discarded hypodermic needle. Also called diamond pickup needle;
diamond pickup tube; diamond pipe. Long

diamond pipe

a. Term used for an occurrence of kimberlite in volcanic pipes large
enough and sufficiently diamondiferous to be minable. The size and shape
of these pipes depend on the position of the planes of structural weakness
in the country rock through which the molten kimberlite passed. They may
be columnar, tabular, or irregular in shape, and where mining is deep
enough the diamond pipe is found to decrease in area and assume a dikelike
habit. Chandler
b. See:diamond needle

diamond powder

See:diamond dust

diamond pressure

The proportional amount of the total feed pressure applied to a diamond
bit theoretically borne by an individual diamond inset in the face of the
bit. Also called pressure per diamond; pressure per stone; stone pressure.
Long

diamond-pyramid hardness test

An indention hardness test employing a 136 degrees diamond-pyramid
indenter and variable loads enabling the use of one hardness scale for all
ranges of hardness from very soft lead to tungsten carbide.
See also:Vickers hardness test

diamond saw

A circular metal disk having diamonds or diamond dust inset in its cutting
or peripheral edge. Employed to cut rocks and other brittle substances.
See also:diamond wheel

diamond-saw splitter

See:core saw

diamond scale

Instrument on which diamonds are weighed with weight units calibrated in
carats; scales vary from a folding 50-carat-capacity type, small enough to
fit in a coat pocket when closed, to those large enough to weigh several
thousand carats at one time. Long

diamond scrap

As used in the diamond-drilling industry; broken diamonds and diamond
fragments deemed unfit for reuse in a diamond bit. In other industries
using diamond-pointed tools, any piece of diamond salvaged from a tool and
deemed unfit for reuse in the same kind of tool. Long

diamond screen

A perforated metal or wirecloth sieve used to sort diamonds or fragments
of diamonds according to size. Long

diamond-set bit

A rock-boring or rock-cutting tool, the cutting points of which are inset
diamonds. Long

diamond-set inserts

Small, shaped metallic slugs inset with diamonds designed to be brazed or
welded into slots or depressions machined in a metal bit or reaming-shell
blank. Long

diamond-set ring

A powdered metal-alloy band encircling a reaming shell in which diamonds
are inset mechanically. Long

diamond spar

Syn:corundum

diamonds per carat

The number of relatively equal size diamonds having a total weight of 1
carat. Also called stone per carat. Long

diamond tin

Large bright crystals of cassiterite. Fay

diamond-tooth saw

A circular saw for cutting stone with points of the teeth made of pieces
of diamonds. Mersereau, 2

diamond washer

An apparatus used for washing diamondiferous gravel.

diamond wheel

a. A grinding wheel in which crushed and sized industrial diamonds are
held in a resinoid, metal, or vitrified bond. ASM, 1
b. See:diamond saw

dianite

See:columbite

diaphaneity

a. The quality or state of being diaphanous. Specif., the ability of a
mineral to transmit light. CF:transparent; semitransparent; translucent;
opaque. Webster 3rd; Fay
b. Degrees of transparency of minerals. CF:transparent; translucent;
opaque.
c. See:transparency

diaphanous

Allowing light to show or to shine through. Webster 3rd

diaphorite

a. See:allagite
b. A monoclinic mineral, Pb2 Ag3 Sb3 S8 .

diaphragm

A porous or permeable membrane separating anode and cathode compartments
of an electrolytic cell from each other or from an intermediate
compartment. ASM, 1

diaphragm jig

In the gravity concentration of minerals, a jig with a flexible diaphragm
used to pulse water. The Bendelari, Pan-American, Denver, and Conset are
examples. Pryor, 1

diaphragm pump

A positive displacement pump used for lifting small quantities of water
and discharging them under low heads. It has a plunger arm operating
either on an eccentric shaft or a rocker arm thrusting on a rubber
diaphragm stretched over a cylinder. As the diaphragm is depressed, the
water and air in the cylinder are forced out through the discharge side of
the pump. As the diaphragm is lifted, a vacuum is created in the cylinder,
and water is forced in. Carson, 1

diaphragm-type washbox

A washbox in which the pulsating motion is produced by the reciprocating
movement of a diaphragm. BS, 5

diaphthoresis

See:retrograde metamorphism

diaphthorite

A crystalline rock in which minerals characteristic of a lower metamorphic
grade have developed by retrograde metamorphism at the expense of minerals
peculiar to a higher metamorphic grade. AGI

diapir

A dome or anticlinal fold in which the overlying rocks have been ruptured
by the squeezing-out of plastic core material. Diapirs in sedimentary
strata usually contain cores of salt or shale; igneous intrusions may also
show diapiric structure.

diapir fold

An anticline in which a mobile core, such as salt, has ruptured the more
brittle overlying rock. Syn:piercement dome; piercement fold.

diaschistic

Said of the rock of a minor intrusion that consists of a differentiate,
i.e., its composition is not the same as that of the parent magma.
CF:aschisite; aschistic. AGI

diaspore

An orthorhombic mineral, AlO(OH) ; white, colorless, or pale tints; in
bauxite and emery deposits; a source of aluminum. Formerly spelled
disaporite. Syn:kayserite

diaspore clay

A high-alumina refractory clay consisting essentially of the mineral
diaspore. It has been interpreted as a desilication product of associated
flint clay and other kaolinitic materials. Commercial diaspore of
first-grade quality contains more than 68% alumina.
See also:burley clay

diasporogelite

A colloidal form of aluminum hydroxide in bauxite. Syn:sporogelite;
cliachite. English

diastem

A relatively short interruption in sedimentation, involving only a brief
interval of time, with little or no erosion before deposition is resumed;
a paraconformity of very small time value. AGI

diasterism

Asterism seen by transmitted light. See also:asterism; epiasterism.

diastrophism

The processes of deformation in the Earth's crust that produce its
continents and ocean basins, plateaus and mountains, and major folds and
faults. Syn:tectonism

diathermanous

a. Transmitting infrared radiation. Webster 3rd
b. Allowing the free passage of the rays of heat as a transparent body
allows free passage of light. Standard, 2

diatom

A microscopic unicellular plant with an envelope (frustule) or outer
skeleton of hydrated silica, close to opal in composition, and usually in
two parts. Diatoms inhabit both fresh water and salt water, and in places
their frustules form masses of diatomaceous earth or shale hundreds of
feet thick.

diatomaceous

Composed of or containing diatoms or their siliceous remains. AGI

diatomaceous earth

See:diatomite

diatomite

A light-colored soft friable siliceous sedimentary rock, consisting
chiefly of opaline frustules of the diatom, a unicellular aquatic plant
related to the algae. Some deposits are of lake origin, but the largest
are marine. Owing to its high surface area, high absorptive capacity, and
relative chemical stability, diatomite has a number of uses, esp. as a
filter aid and as an extender in paint, rubber, and plastics. The term is
generally reserved for deposits of actual or potential commercial value.
Syn:diatomaceous earth; kieselguhr; guhr; tripoli. Obsolete syn:
infusorial earth; tripoli-powder. See also:tripolite
AGI

diatom ooze

A deep-sea deposit, resembling flour when dry, largely composed of the
frustules of diatoms and containing a small but variable proportion of
calcareous organisms and mineral particles. Holmes, 2

diatomous

Having a single distinct diagonal cleavage; applied to certain crystals.
Standard, 2

diatom saprokol

A saprokol containing a large amount of diatoms. Tomkeieff

diatreme

A breccia-filled volcanic pipe that was formed by a gaseous explosion.
AGI

dibutyl carbinol

2-methyl-l-butanol; a frother used in the flotation process.
Pryor, 1

dice mineral

A Wisconsin term for small cubic galena. Fay

dicey clay

Any clay or mudstone with a cuboidal fracture, as in the Kimmeridge clay.
Arkell

dichroic colors

A term loosely used to refer to either the two colors observable in a
dichroic stone or the three colors in a trichroic stone.
Syn:twin colors

dichroism

a. Pleochroism of a crystal, which is indicated by two different colors or
two shades of the same color. In plane-polarized light, dichroic minerals
change color upon rotation. CF:trichroism; pleochroism.
b. Color change owing to change in the spectrum of illumination; e.g.,
alexandrite, which is green in sunlight but red by tungsten incandescent
light. See also:chrysoberyl
c. The property of some surfaces to reflect light of one color while
transmitting light of another.

dichroite

A former name for iron-rich cordierite that may have been the navigation
stone of the Vikings; reveals maximum light polarization in the southern
sky.

dichromate

A salt containing the divalent (Cr2 O7 )2- radical.

dichroscope

a. An instrument designed to detect two of the different colors emerging
from pleochroic (that is, dichroic or trichroic) minerals. Contains a
rhomb of Iceland spar and a lense system in a short tube, and exhibits the
two colors side by side. See also:dichroic colors
b. An instrument to detect two colors transmitted by pleochroic minerals
and display them side-by-side.

dickensonite

A monoclinic mineral, (K,Ba)(Na,Ca)5 (Mn,Fe,Mg)14 Al(PO (sub
4) )12 (OH,F)2 ; forms a series with arrojadite.

dickinsonite

A green, hydrous phosphate mineral, chiefly of manganese, iron, and
sodium. Fay

dickite

A monoclinic mineral, Al2 Si2 O5 (OH)4 ;
kaolinite-serpentine group; polymorphous with halloysite, kaolinite, and
nacrite, each having a different stacking order of identical layers
(polytypy); commonly in hydrothermal veins.

diclinic

A crystal having two of the three axes inclined to the third and
perpendicular to each other. Standard, 2

didymium

a. The name applied to commercial mixtures of rare-earth elements obtained
from monazite sand by extraction followed by the elimination of cerium and
thorium from the mixture. The name is used like that of an element in
naming mixed oxides and salts. The approximate composition of didymium
from monazite, expressed as rare-earth oxides, is 46% lanthana, La2
O3 ; 10% praseodymia, Pr6 O11 ; 32% neodymia, Nd (sub
2) O3 ; 5% samaria, Sm2 O3 ; 0.4% yttrium earth
oxides; 1% ceria, CeO2 ; 3% gadolinia, Gd2 O3 ; and
2% others. The mineral bastnaesite could also be a source of didymium
mixtures. CCD, 2
b. The name didymium has also been applied to mixtures of the elements
praseodymium and neodymium because such mixtures were once thought to be
an element; it was assigned the symbol, Di. CCD, 2

didymolite

A former name for a plagioclase mineral.

die

a. See:bell tap
b. A piece of hard iron, placed in a mortar to receive the blow of a stamp
or in a pan to receive the friction of a muller as ore is crushed between
the die and the stamp or muller. Fay

die-casting alloys

Alloys that are suitable for die casting and that can be relied on for
accuracy and resistance to corrosion when cast. Aluminum-, copper-, tin-,
zinc-, and lead-base alloys are those generally used. CTD

die collar

See:bell tap

dielectric

a. A material that offers relatively high resistance to the passage of an
electric current but through which magnetic or electrostatic lines of
force may pass. Most insulating materials, for example, air, porcelain,
mica, and glass, are dielectrics; and a perfect vacuum would constitute a
perfect dielectric. NCB
b. An insulator. A term applied to the insulating material between the
plates of a capacitor. Hunt

dielectric constant

The numerical expressions of the resistance to the passage of an electric
current between two charged poles. It is the ratio of the attraction of
two oppositely charged poles as measured in a vacuum to their attraction
in a substance. The dielectric constant, which corresponds to permeability
in magnetic materials, is a measure of the polarizability of a material in
an electric field. This property determines the effective capacitance of a
rock material and consequently its static response to any applied electric
field, either direct or alternating. The dielectric constant of a vacuum
is unity. Hess; Dobrin

dielectric heating

A method of high-frequency heating in which the object to be heated, which
must be nonconducting, is placed in a high-frequency alternating field
where it is heated by the continually reversed polarization of the
molecules. Applied in the foundry for drying sand cores. Osborne

dielectric separation

Method of ore treatment based on differences between dielectric constants
of minerals suspended in an intermediate nonconducting fluid, when
subjected to electric fields. Of limited use in laboratory work.
Pryor, 1

dielectric strength

The maximum potential gradient that a dielectric material can withstand
without rupture. Lowenheim

dienerite

An isometric mineral, Ni3 As ; in gray-white cubes at Radstadt,
Salzburg, Austria.

die nipple

See:bell tap

diesel hammer

A pile driving drophammer operated by a type of diesel engine.
Hammond

dieseling

In a compressor, explosions of mixtures of air and lubricating oil in the
compression chambers or other parts of the air system. Nichols, 1

diesel particulate matter

a. Exhaust material, excluding water, that results from the incomplete
combustion of fuel and lubricating oil in a diesel engine. The
particulates collected on a filter after dilution of the exhaust with
ambient air, are carbonaceous solid chain aggregates with adsorbed or
condensed organic compounds. SME, 1
b. The fumes (solid condensation particles) and adsorbed gases that are
emitted from a diesel engine as a result of the combustion of diesel fuel.
Abbrev. DPM. DPM is a complex mixture of chemical compounds, composed of
nonvolatile carbon, hundreds of thousands of different adsorbed or
condensed hydrocarbons, sulfates, and trace quantities of metallic
compounds. DPM is of special concern because it is almost entirely
respirable, with 90% of the particles, by mass, having an equivalent
aerodynamic diameter of less than 1.0 mu m. This means that the particles
can penetrate to the deepest regions of the lungs and, if retained, cause
or contribute to the development of lung disease. Of equal concern is the
ability of DPM to adsorb other chemical substances, such as (1)
potentially mutagenic or carcinogenic polynuclear aromatic hydrocarbons
(PAHs); (2) gases, such as sulfur dioxide and nitrogen dioxide; and (3)
sulfuric and nitric acids. DPM carries these substances into the lungs,
where they may be removed and transported by body fluids to other organs,
where they may cause damage.

diesel rig

Any drill machine powered by a diesel engine. Long

diesel truck

In opencast mining, a powerful and robust diesel-engined vehicle carrying
from a few to more than 100 cubic yards of earth or rock. Also used in
trackless transport in tristate mines. Pryor, 3

die steels

Steels of plain-carbon or alloy types; they must be of high quality, which
is usually attained by special methods of processing. Essentially, they
are steels used in making tools for cutting, machining, shearing,
stamping, punching, and chipping. USBM, 5

Dietert tester

An apparatus for the direct reading of a Brinell hardness after impression
without the aid of magnification or conversion tables. Osborne

dietzite

A monoclinic mineral, Ca2 (IO3 )2 (CrO4 ) ;
dark golden-yellow; forms prismatic, tabular, fibrous, or columnar
crystals; at Atacama, Peru.

difference in gage of drill bits

The difference in diameter of the bits when passing from one length
(change) of drill steel to the next longer one of a set. Fraenkel

difference of potential

The difference in electrical pressure existing between any two points in
an electrical system or between any point of such a system and the Earth.
Determined by a voltmeter. Fay

differential compaction

The uneven settling of homogeneous earth material under the influence of
gravity (as where thick sediments in depressions settle more rapidly than
thinner sediments on hilltops) or by differing degrees of compactability
of sediments (as where clay loses more interstitial water and comes to
occupy less volume than sand). AGI

differential curvature

A quantity represented by the acceleration due to gravity times the
difference in the curvatures in the two principal planes; i.e., g(1/p (sub
1) - 1/p2 ) where p1 and p2 are the radii of
curvature of the two principal planes. AGI

differential erosion

Erosion that occurs at irregular or varying rates, caused by the
differences in the resistance and hardness of surface materials; softer
and weaker rocks are rapidly worn away, whereas harder and more resistant
rocks remain to form ridges, hills, or mountains. AGI

differential fault

See:scissor fault

differential grinding

Application of comminution in such a way as to accentuate differences in
grindability between the various mineral species in the ore. Therefore, in
suitable cases, the relatively tough mineral particles remain coarse while
the more friable ones are finely ground. Pryor, 1

differential pressure flowmeter

An instrument for measuring water and water-ore slurries in ore dressing
and coal dressing processes.

differential pumping engine

A compound direct-acting pumping engine, generally of the horizontal
class. Fay

differential settlement

Nonuniform settlement; the uneven lowering of different parts of an
engineering structure, often resulting in damage to the structure.
See also:settlement

differential thermal analysis

a. A method of analyzing a variety of minerals, esp. clays and other
aluminiferous minerals. The method is based upon the fact that the
application of heat to many minerals causes certain chemical and physical
changes and is reflected in endothermic and exothermic reactions. By
comparing the changes in temperature of a mineral heated at a definite
rate with that of a thermally inert substance (alumina, for example)
heated under the same conditions, a curve or pattern is obtained that is
characteristic of the particular mineral under examination.
Henderson
b. Thermal analysis carried out by uniformly heating or cooling a sample
that undergoes chemical and physical changes, while simultaneously heating
or cooling in identical fashion a reference material that undergoes no
changes. The temperature difference between the sample and the reference
material is measured as a function of the temperature of the reference
material. Abbrev: DTA. AGI

differential weathering

Weathering that occurs at different rates, as a result of variations in
composition and resistance of a rock or differences in intensity of
weathering, and usually resulting in an uneven surface where more
resistant material protrudes above softer or less resistant parts.
Syn:selective weathering

differentiate

A rock formed as a result of magmatic differentiation. AGI

differentiated

Said of an igneous intrusion in which there is more than one rock type,
owing to differentiation. AGI

differentiation

See:magmatic differentiation

diffraction

The cooperative scattering of any electromagnetic radiation where it
encounters an obstacle, esp. the edge of an obstacle, resulting in
constructive and destructive interference. Also, a single event resulting
from constructive interference. See also:optical diffraction;
X-ray diffraction. Syn:wave diffraction

diffraction grating

An optical device having equidistant fine lines (on the order of
wavelengths of visible light) scribed on glass for transmission, or on
metal for reflection diffraction, of monochromatic light.

diffraction pattern

a. Diffracted X-rays recorded on film, giving a means of identification of
a powder.
b. A record of diffracted X-rays on film or paper showing angles of
diffraction of monochromatic radiation; used for characterization or
identification of a crystalline substance. CF:Laue photograph

diffuser

a. The inner shell and water passages of a centrifugal pump.
Nichols, 1
b. See:evase

diffuser chamber

A chamber in a turbine pump consisting of a number of fixed blades. On
leaving the impeller, the water is guided outward by these blades with the
minimum of eddying and swirling. See also:turbine pump

diffusion of gases

The property that all gases possess of mixing with each other.
Nelson

diffusivity

The relative rate of flow per unit area of a particular constituent of a
mixture divided by the gradient of composition, temperature, or other
property considered to be causing the diffusion.

dig

a. To mine coal; applied to bituminous workings. See also:gouge
b. To excavate; make a passage into or through, or remove by taking away
material.
c. Crushed strata. Nelson

dig-down pit

A pit that is below the surrounding area on all sides. Also called sunken
pit. Nichols, 1

digenite

An isometric mineral, Cu9 S5 ; blue to black; in veins with
chalcocite; a source of copper. Syn:blue chalcocite; alpha chalcocite.
CF:copper sulfide

digger

a. One that digs in the ground, as a miner or a tool for digging.
Webster 3rd
b. A worker who is paid by the ton for coal produced; a miner in the
stricter sense. Originally the digger mined or undermined the coal; now
the term is applied to the worker who merely shoots out the coal.
Fay
c. A machine for removing coal from the bed of streams, the coal having
washed down from collieries of culm banks above. Zern

digger edges

The formed serrated edges of the buckets used for digging purposes on a
bucket loader.

digger tools

The formed tools interspaced with the buckets of a bucket loader to aid in
digging action.

digging

Mining operations in coal or other minerals.

digging bit

According to English drillers, a noncoring bit usually similar to a steel
drag or mud bit. Long

digging cycle

Complete set of operations a machine performs before repeating them.
Nichols, 2

digging height

See:bank height

digging line

On a shovel, the cable that forces the bucket into the soil. Called crowd
in a dipper shovel, drag in a pull shovel, and dragline and closing line
in a clamshell. Nichols, 1

digging resistance

The resistance that must be overcome to dig a formation. This resistance
is made up largely of hardness, coarseness, friction, adhesion, cohesion,
and weight. Nichols, 3

diggings

Applicable to all mineral deposits and mining camps, but as used in the
United States it is usually applied to placer mining only.
See also:bar diggings

digital map

A map using data in a software format so that the maps have the
characteristic of layered features on an overlay generated by
computer-aided drafting and design to plot these features. SME, 1

dihedral

Having two sides, as a figure; having two faces, as a crystal. Fay

dihydrite

See:pseudomalachite

dike

a. An earthen embankment, as around a drill sump or tank, or to impound a
body of water or mill tailing.
b. A tabular igneous intrusion that cuts across the bedding or foliation
of the country rock. Also spelled: dyke. CF:sill; sheet.
See also:dikelet

dikelet

A small dike. There is no agreement on specific size distinctions.
AGI

dike ridge

A wall-like ridge created when erosion removes softer material from along
the sides of a dike.

dike rock

The intrusive rock comprising a dike. AGI

dike set

A group of parallel dikes. CF:dike swarm

dike swarm

A group of dikes, which may be in radial, parallel, or en echelon
arrangement. Their relationship with the parent plutonic body may not be
directly observable. CF:dike set

dilatancy

An increase in the bulk volume of a granular mass during deformation,
caused by a change from close-packed structure to open-packed structure,
accompanied by an increase in the pore volume. The latter is accompanied
by rotation of grains, microfracturing, and grain boundary slippage.
AGI

dilatational wave

See:P wave; compressional wave.

dilation

Deformation by a change in volume but not shape. Also spelled: dilatation.
AGI

dilational transformation

A phase transformation requiring change in coordination about a cation,
e.g., quartz with silica tetrahedra to stishovite with silica octahedra.
CF:reconstructive transformation; displacive transformation;
rotational transformation.

dilation vein

A mineral deposit in a vein space formed by bulging of the walls,
contrasted with veins formed by wall-rock replacement. AGI

diligence

The attention and care legally required of a person (for example a claim
holder) while that person has temporary possession of a property. With
regards to mining claims, the courts have said that due diligence requires
that "the exploration for minerals should be made within a reasonable
time" and that, "The failure to make such exploration within a reasonable
time, and to make it with such thoroughness and certainty as to determine
the existence of mineral or oil, would be fatal to the agreement (claim)".
Legal requirements for "diligence" may include annual improvements to the
claim and the filing of reports and notices. Webster 3rd

dillenburgite

An impure variety of chrysocolla containing copper carbonate.

dilly rider

In bituminous coal mining, a laborer who rides and attends a dilly (light
wagon, truck, or water cart) used to haul coal or water underground or at
the surface of a mine, loading, unloading, and cleaning it. DOT

diluent

a. That which dilutes or makes more fluid; a fluid that weakens the
strength or consistency of another fluid upon mixing. Fay
b. Waste rock in ore. Hess
c. In solvent extraction, the inert liquid used to dissolve the
extractant. Newton, 1

dilute medium

Medium of specific gravity below that in the separating bath and usually
occurring as a result of spraying the bath products for the removal of
adhering medium solids. BS, 5

dilution

The contamination of ore with barren wall rock in stoping. The assay of
the ore after mining is frequently 10% lower than when sampled in place.
See also:contamination

dimensional rated capacity

The weight of a specified material per foot of belt length that a belt
conveyor will transport. NEMA, 2

dimension stone

Any rock suitable for construction purposes, as distinguished from crushed
stone or aggregate.

dimetric system

Same as tetragonal system.

dimorphism

The property of a chemical compound to crystallize in either of two
different crystal structures, e.g., CaCO3 as trigonal calcite and
as orthorhombic aragonite. Noun: dimorph. Adj: dimorphic.
CF:trimorphism; polymorphism.

dimorphite

An orthorhombic mineral, As4 S3 ; orange-yellow; a volcanic
product closely related to orpiment.

dingot

An oversized derby (possibly a ton or more) of a metal produced in a bomb
reaction, such as uranium from uranium tetrafluoride and magnesium. The
term ingot for these metals is reserved for massive nits produced in
vacuum melting and casting. See also:biscuit

Ding's magnetic separator

In its earlier form, a mineral separator to which the material was fed by
a vibrating conveyor and passed through successive zones of magnetic
influence. The zones were covered by the rims of rotating disks, which
became magnetized, carried the particles having magnetic susceptibility
out of the fields, were demagnetized, and dropped the concentrate beyond
the edge of the belt. Now made with rollers having an induced magnetism;
dried, finely crushed ore passed over the rollers in a thin stream from
which particles attracted by the magnet are drawn out.
Hess; Liddell

dinite

A yellowish hydrocarbon having a low melting temperature; in lignite.

dinkey

A small locomotive used to move cars in and about mines and quarries.
Fay

dint

To cut into the floor of a roadway to obtain more headroom.
Fraenkel

dioctahedral

Said of layered silicates having two-thirds of the voids in the octahedral
layer filled, generally with trivalent cations. CF:trioctahedral

diopside

A monoclinic mineral, CaMgSi2 O6 ; pyroxene group; white to
light green; in metamorphic rocks, esp. contact metamorphosed limestones;
where transparent, a semiprecious gemstone. Symbol: Di or di.
See also:malacolite

dioptase

A trigonal mineral, CuSiO2 (OH)2 ; emerald green; in the
oxidized zones of copper deposits; a source of copper. Also called emerald
copper, Zaire emerald.

diorite

A group of plutonic rocks intermediate in composition between acidic and
basic, characteristically composed of dark-colored amphibole (esp.
hornblende), acid plagioclase (oligoclase, andesine), pyroxene, and
sometimes a small amount of quartz; also, any rock in that group; the
approximate intrusive equivalent of andesite. Diorite grades into
monzonite with an increase in the alkali feldspar content. Etymol: Greek
diorizein, to distinguish, in reference to the fact that the
characteristic mineral, hornblende, is usually identifiable
megascopically. CF:dolerite; gabbro. See also:diabase

dioxide ore

A term that has been used somewhat in the Western United States for
manganese ore. Hess

dip

a. The angle at which a bed, stratum, or vein is inclined from the
horizontal, measured perpendicular to the strike and in the vertical
plane. See also:pitch; hade; angle of dip; apparent dip. CF:plunge
Lewis
b. To be inclined or dip at an angle.
c. The angle of a slope, vein, rock stratum, or borehole is measured from
the horizontal plane downward. Long
d. The direction of the true or steepest inclination. Mason
e. The lower workings of a mine. Hudson
f. The slope of layers of soil or rock. Nichols, 1
g. A dip entry, dip room, etc. A heading driven to the full rise in steep
mines. Fay
h. In terrestrial magnetism, the angle formed by the lines of total
magnetic force and the horizontal plane at the Earth's surface; reckoned
positive if downward. See also:apparent dip; full dip. Hy
i. In mines, the increase in depth of a moored mine case, due to current
force against the case and cable. Hy

dip calculation

Any of a number of methods of converting observed seismic arrival time
values to the dip of a reflector; most commonly the conversion of delta T
values to dip values by a conversion factor based upon the geometry of the
seismic array and approximate seismic propagational velocity. AGI

dip compass

An instrument to measure magnetic intensity by means of a magnetic needle
fixed to swing in a vertical plane so that it can readily be deflected
downward by magnetic materials. Used to explore for subsurface deposits
containing magnetic materials. May also be called dip needle, dipping
compass, dipping needle, doodle bug magnetometer. Long

dip-corrected map

A map that shows stratified formations in their original position before
movement.

dip cut

In cutting out blocks of stone, the cut that follows a line at right
angles to the strike.

dip entry

An entry driven downhill so that water will stand at the face. If it is
driven directly down a steep dip it becomes a slope. See also:entry;
slope.

dip equator

See:aclinic line

dip face

A face proceeding toward the dip of the seam. Briggs

dip fault

A fault that strikes approx. perpendicular to the strike of the bedding or
cleavage. CF:oblique fault; strike fault. Billings

diphead

A drift inclined along the dip of a coal seam. Webster 3rd

diphead level

a. A mine level connecting an engine shaft with the rooms or chambers.
Standard, 2
b. The main level, drift, or slope.

dip joint

A joint that strikes approx. perpendicularly to the strike of the bedding
or cleavage. Billings

dip meter

a. An instrument used to record the amount and direction of the dip of
strata exposed in the sides of a borehole. BS, 9
b. See:dipmeter

dipmeter

A dipmeter measures both the amount and direction of dip by readings taken
in the borehole and can be operated by using either self-potential or
resistivity measurements. Sinclair, 3

dip needle

An obsolete type of magnetometer used for mapping high-amplitude magnetic
anomalies. It consists of a magnetized needle pivoted to rotate freely in
a vertical plane, with an adjustable weight on the south side of the
magnet. See also:Hotchkiss superdip

dipole

a. Coordinate valence link between two atoms. Pryor, 3
b. Electrical symmetry of a molecule. When a molecule is formed by sharing
two electrons between a donor atom and an acceptor, it is more positive at
the donor end and more negative at the acceptor end, and has a dipole
moment of the order of 10-18 electrostatic unit. Dipole moment is
also the couple required to maintain the dipole at right angles to an
electrical or magnetic field of unit intensity. Pryor, 3

dipole moment

Product of the dipole charge and the dipole length. Van Vlack

dippa

Corn. A small pit sunk on a lode to catch water; a pit sunk on a bunch
ore.

dipper

a. A digging bucket rigidly attached to a stick or arm on an excavating
machine; also the machine itself.
b. N. of Eng. A downthrow, or a fault.

dipper dredge

A dredge in which the material excavated is lifted by a single bucket on
the end of an arm, in the same manner as in the ordinary steam shovel.
Fay

dipper dredger

A dredger consisting of a single large bucket at the end of a long arm,
swung in a vertical plane by gearing. The bucket capacity may be up to
about 12 cubic yards. See also:dredger

dipper factor

See:fill factor

dipper stick

a. The straight shaft that connects the digging bucket with the boom on an
excavating machine or power shovel. Nichols, 2
b. Standard revolving dipper shovel. Nichols, 2

dipping needle

A needle, consisting of a steel magnet, similar to that in a miners' dial,
but pivoted at the center so as to be free to rotate vertically. It is
used to locate the presence of shallow deposits of magnetic ores. The
magnetometer has now replaced the dipping needle for large-scale
prospecting work. Syn:dip compass
Nelson; Long

dipping weight

See:pickup

dip reading

An angular measurement taken in an inclined borehole by using one of
several types of borehole-surveying devices or techniques. Long

dip separation

The distance or separation of formerly adjacent beds on either side of a
fault surface, measured along the dip of the fault. CF:dip slip
AGI

dip shift

In a fault, the shift or relative displacement of the rock units parallel
to the dip of the fault, but outside the fault zone itself. CF:dip slip;
strike shift. AGI

dip shooting

A system of seismic surveying in which the primary concern is determining
the dip and position of reflecting interfaces rather than in tracing such
interfaces continuously. AGI

dip slip

In a fault, the component of the movement or slip that is parallel to the
dip of the fault. CF:dip separation; strike slip; oblique slip;
total displacement; dip shift. AGI

dip-slip fault

A fault on which the movement is parallel to the dip of the fault.
CF:strike-slip fault

dip slope

A landform developed in regions of gently inclined strata, particularly
where hard and soft strata are interbedded. A long, gentle sloping surface
that parallels the dip of the bedding planes of the strata below ground.
See also:back slope

dip split

A current of intake air directed into or down a dip.

dip switch

a. A slant or piece of track connecting the back entry or air course of a
dipping coal seam with the main entry or gangway. Fay
b. Circuit board component that consists of several switches used to alter
circuit performance.

dip test

As used in the diamond-drilling industry, an angular measurement of the
inclination of a borehole taken with a clinometer.
See also:acid-dip survey

dip throw

The component of the slip measured parallel with the dip of the strata.
Fay

dip valley

A valley trending in the direction of the general dip of the rock layers
of a region.

dip workings

a. The workings on the lower side of the level or gate road in an inclined
seam. Dip workings may present water problems and require pumping. Also
called deep workings. Nelson
b. Underhand excavations in which miner works downward and lifts spoil to
removal point. Not self-draining. Pryor, 3

dipyramid

A closed form consisting of orthorhombic, trigonal, tetragonal, or
hexagonal positive and negative pyramids. Syn:bipyramid
CF:bipyramid; pyramid.

dipyre

A variety of scapolite having marialite:meionite between 3:1 and 3:2.
Syn:mizzonite; dipyrite.

dipyrite

See:dipyre; pyrrhotite.

direct-acting controller

One in which an increasing measured value in the input signal produces an
increasing controller output, and vice versa. Pryor, 3

direct-acting haulage

See:direct-rope haulage

direct-arc furnace

One in which an arc is struck between an electrode and the material
charged into the furnace. Pryor, 3

direct attack

A method of effecting extinction of mine fires using water or the effluent
of chemical fire extinguishers. When a mine fire is readily accessible to
the firefighting personnel, extinction of it may be achieved by direct
application of some substance that will cool down the hot mass below its
ignition temperature, or, in the case of oils, will arrest the
volatilization process by sealing or emulsifying the oil surface.
Mason

direct firing

a. The combustion of coal effected by burning directly on a grate.
Fay
b. A method of firing wherein the products of combustion come in contact
with the ware. ACSB, 2

direct flushing

Flushing in which the water rises along the rod on its outer side; i.e.,
between the walls of the borehole and the rod, and with such a velocity
that the broken rock fragments are carried up by this water current.
Stoces

direct haulage

The system in which an engine with a single drum and rope draws loaded
trucks up an incline. The empties run downhill dragging the rope after
them. CTD

direct initiation

The placing of the detonator in the last cartridge to be inserted in the
shothole with the active end of the detonator pointing inward. This
position tends to minimize the risk of gas ignition.
See also:inverse initiation

direction

a. Angle to the right (clockwise) from an arbitrary zero direction. Used
chiefly in triangulation. Seelye, 2
b. See:trend

directional drilling

a. The art of drilling a borehole wherein the course of the hole is
planned before drilling. Such holes are usually drilled with rotary
equipment and are useful in drilling divergent tests from one location,
tests that otherwise might be inaccessible, as controls for fire and wild
wells, etc. AGI
b. Drilling in which the course of a borehole is controlled by deflection
wedges or other means. The technique of directional drilling is used (1)
to deflect a deviated borehole back onto course and (2) to deflect a
borehole off course, either to bypass an obstruction in the hole or to
take a second core. Syn:slant drilling

directional solidification

The solidification of molten metal in a casting in such a manner that feed
metal is always available for the portion just solidifying. ASM, 1

directional work

See:directional drilling

direction-finding methods

Electromagnetic exploration methods in which one determines the direction
of the magnetic field associated with the currents. Schieferdecker

direction indicator

Any one of a number of geophysical devices used to determine the deviation
of a borehole from vertical. AGI

direction of dip

See:line of dip

direction of strata

a. The strike or line of bearing.
b. The direction of the line formed by the intersection of the individual
stratum with the horizontal plane. The direction of this line is
customarily referred to north. See also:strike

direction of tilt

a. The azimuth of the principal plane of an aerial photograph. AGI
b. The direction of the principal line on a photograph. AGI

directivity index

A measure of the directional properties of a transducer. It is the ratio
in decibels of the average intensity of response over the whole sphere
surrounding the projector or hydrophone to the intensity or response on
the acoustic axis. Hy

direct labor

A method of carrying out mining works in which the owners, Board, or
Authority, carry out the scheme by employing labor and purchasing the
necessary equipment. The method is in contrast to work entrusted to
outside contractors for performance at a fixed sum. Nelson

direct lattice

A symmetrical array of points in direct space; used when comparison is
made with the direct lattice. Syn:Bravais lattice; crystal lattice.

direct oxidation

The reaction of metals with dry gases, leading to the formation of oxides
or other compounds on the surface; it does not occur to a pronounced
extent except at elevated temperature. CTD

direct plot

In a graph of particle distribution (screen analysis), a plot in which the
abscissa shows the size and the ordinate shows the percentage of sample of
that size. Pryor, 1

direct raw-water cooling system

A cooling system in which water, received from a constantly available
supply, such as a well or water system, is passed directly over the
cooling surfaces of the rectifier and discharged. Coal Age, 1

direct-reading capillary chart

A graduated scale printed on transparent paper, which, when used in the
prescribed manner, enables one to determine the true angle a borehole is
inclined from readings taken directly on the etch plane in an acid bottle.
This eliminates the need for a protractor or goniometer and for a
capillarity-correction chart. Long

direct-rope haulage

a. A system of incline haulage, comprising one rope and one drum. The
engine hauls up the journey of loaded cars, then the empties are connected
to the rope and returned to the bottom by gravity.
See also:balanced direct-rope haulage
haulage. Nelson
b. Haulage in which a loaded truck is pulled up the slope by a hoist while
an empty one descends, perhaps passing halfway on a loop of single track.
Also called brake incline; engine plane. Pryor, 3

direct shipping ore

See:natural ore

Dirigem

A copyrighted trade name for green synthetic spinel.

dirt band

A thin stratum of shale or other inorganic rock material in a coal seam.
Syn:shale band; dirt bed; dirt parting; stone band. AGI

dirt bed

a. Eng. A thin stratum of soft, earthy material interbedded with coal
seams. Syn:dirt band
b. Old soil in which trees, fragments of timber, and numerous plants are
found. Fay

dirt bing

Scot. A debris heap; a waste heap.

dirt parting

See:dirt band

dirt scraper

A road scraper or a grading shovel, used in leveling or grading ground.
Fay

dirt slip

See:clay vein

dirty coal

Scot. A coal seam with thick partings of blaes or fireclay; a very ashy
coal.

disability glare

The glare resulting in reduced visual performance and visibility caused by
the action of stray light, which enters the eye and scatters within. It
causes a "veiling luminescence" over the retina, which, in turn, has the
effect of reducing the perceived contrast of the objects being viewed.
CF:discomfort glare

discard

a. The material extracted from the raw coal and finally thrown away. Also
called dirt; stone. BS, 5
b. The portion of an ingot cropped off to remove the pipe and other
defects. Also called crop. CTD

discharge

a. The production or output from crushing or processing machines, such as
ball mills, or thickeners.
b. The outflow from a pump, drill hole, piping system, or other mechanism.
c. The quantity of water, silt, or other mobile substances passing along a
conduit per unit of time; rate of flow in cubic feet per second, gallons
per day, etc.
d. The rate of flow at a given moment, expressed as volume per unit of
time. AGI

discharge chute

A chute used to receive and direct material or objects from a conveyor.

discharge head

The sum of static and dynamic head. The vertical distance between intake
and free delivery of pump is static head. Allowance for friction, power
loss, propeller slip, and issuing velocity is made for calculating the
overall discharge head. Pryor, 3

discharge station

A place where bulk materials are removed from a conveyor.

discomfort glare

A sensation of annoyance, or in extreme cases pain, caused by high or
nonuniform distribution of brightness in the field of view. Discomfort
glare is a measure of discomfort or annoyance only.
CF:disability glare

disconformity

An unconformity in which the bedding planes above and below are
essentially parallel, indicating a considerable interval of erosion (or
sometimes of nondeposition), and usually marked by a visible and irregular
or uneven erosion surface of appreciable relief. The term formerly
included what is now known as paraconformity. Syn:parallel unconformity;
nonangular unconformity. See also:angular unconformity

discontinuity

a. An abrupt change in the physical properties of adjacent materials in
the Earth's interior. Mather
b. Any interruption in the normal physical structure or configuration of a
part, such as cracks, laps, seams, inclusions, or porosity. A
discontinuity may or may not affect the usefulness of a part.
ASM, 1

discontinuity lattice

See:lattice

discontinuous deformation

Deformation of rocks accomplished by rupture rather than by flowage.

discontinuous reaction series

A reaction series in which early-formed crystals react with later liquid
by means of abrupt phase changes; e.g., the minerals olivine, pyroxene,
amphibole, and biotite form a discontinuous reaction series.
CF:continuous reaction series

discordance

A lack of parallelism between contiguous strata, e.g., angular
unconformity. Standard, 2; Fay

discordant

a. Said of a contact between an igneous intrusion and the country rock
that is not parallel to the foliation or bedding planes of the latter.
AGI
b. Structurally unconformable; said of strata lacking conformity or
parallelism of bedding or structure. CF:concordant
Syn:unconformable

discordant bedding

See:crossbedding

discovery

a. In mining, the term may be defined as knowledge of the presence of the
valuable minerals within the lines of the location or in such proximity
thereto as to justify a reasonable belief in their existence. But in all
cases there must be a discovery of mineral, in both lode and placer
claims, as distinguished from mere indications of mineral. In other words,
in a lode location there must be such a discovery of mineral as gives
reasonable evidence of the fact either that there is a vein or lode of
rock in place carrying the valuable mineral; or, if it be claimed as
placer ground, that it is valuable for such mining. Ricketts
b. Pac. The first finding of the mineral deposit in place upon a mining
claim. A discovery is necessary before the location can be held by a valid
title. The opening in which it is made is called discovery shaft,
discovery tunnel, etc. The finding of mineral in place as distinguished
from float rock constitutes discovery. See also:mine

discovery claim

A claim containing the original discovery of exploitable mineral deposits
in a given locale, which may lead to claims being made on adjoining areas.
AGI

discovery vein

The original mineral deposit on which a mining claim is based.
CF:secondary vein; discovery claim. AGI

discretization

In kriging, the process of approximating the area of a block by a finite
array of points.

disequilibrium assemblage

An association of minerals not in thermodynamic equilibrium. AGI

dish

a. See:pan; gold pan.
b. The landowner's part of the ore. Fay
c. Gold-bearing gravel or other material found by panning.

disharmonic fold

A fold that varies noticeably in profile form in the various layers
through which it passes. Ant: harmonic fold. AGI

disharmonic folding

Folding in which there is an abrupt change in fold profile when passing
from one folded surface or layer to another. It is characteristic of rock
layers that have significant contrasts in viscosity. An associated
structure is decollement. Ant: harmonic folding. CF:decollement
AGI

disintegrate

a. To break up by the action of chemical and/or mechanical forces.
AGI
b. To separate or decompose into fragments; to break up; hence, to destroy
the wholeness, unity, or identity. Ballard

disintegration

The breaking up and crumbling away of a rock, caused by the action of
moisture, heat, frost, air, and the internal chemical reaction of the
component parts of rocks when acted upon by these surface influences.
See also:mechanical weathering; chemical weathering.
CF:putrefaction

disintegrator

a. A mill for comminuting materials to a fine dry powder such as by impact
breaker. Nelson
b. A machine for reducing by means of impact the particle size of the coal
or pitch binder, or both. Also called beater. CF:impact mill;
hammermill. BS, 5

disk

See:tappet

disk-and-cup feeder

A reagent dispenser used in the flotation process. Cups, mounted around
the periphery of a slowly rotating disk driven by a fractional horsepower
motor, dip into a reservoir of reagent and upon rising deliver a closely
controlled quantity to the process, usually to conditioners.
Pryor, 3

disk coal cutter

A coal cutter whose cutting unit consists of a disk or wheel, armed at its
periphery with cutters. The first disk machine, with detachable picks, was
patented in 1861. The disk coal cutter is obsolescent. Nelson

disk fan

An axial-flow fan with a series of blades formed by cutting and bending
flat sheets or plates. When rotated, the disk imparts to the air a motion
along the axis of the fan shaft. Strock, 2

disk feeder

A feeder consisting of a rotating horizontal metal disk under the opening
of a bin such that the rate of turning or opening of the gate governs the
quantity delivered. Also called rotary table feeder, rotary feed table.
See also:plate feeder

disk filter

A continuous dewatering filter in which the membrane (filter cloth) is
stretched on segments of a disk. These disks rotate through a tank of
slurry. The vacuum inside the disk draws the liquid through the cloth to
discharge; the solids forming a cake on the filter cloth are lifted clear
of the slurry tank and separately discharged, by application of air
pressure behind the filter cloth. Pryor, 3

disk grizzly

See:grizzly

disk mill

A laboratory grinding mill with two circular plates almost parallel, of
which one is fixed while the other rotates. Ore fed centrally between the
plates is ground and discharged peripherally. The disk breaker
(obsolescent) had two saucer-shaped disks working in similar fashion.
Pryor, 3

dislocation

a. Displacement. AGI
b. The shifting of the relative position of a boulder in a borehole or of
the rock on either side of a crack or fissure cutting across a borehole.
Long
c. The offset in a borehole. Also called deviation; throw. Long
d. A general term to describe a break in the strata, for example, a fault.
A washout is a disturbance but not a dislocation. Nelson
e. The displacement of rocks on opposite sides of fracture.
Pryor, 3
f. In metallurgy, the structural defect in metal or crystal produced by
distortion. Pryor, 3
g. A linear crystal defect. Van Vlack

disorder

A state where different ions are distributed randomly in identical
structural positions. See also:long-range order
CF:crystal defect; volume defect.

dispatcher

a. An employee who controls or keeps track of the traffic on haulageways
and informs workers when to move trains or locomotives. BCI
b. See:motor boss
c. A person or electronic device that routes haulage trucks to shovels or
directs trucks from shovels to one of several destinations: ore pass,
crusher, or spoil embankment.

dispatching system

A system employing radio, telephones, and/or signals (audible or visual)
for orderly and efficient control of the movements of trains of cars in
mines.

dispersant

See:dispersing agent

dispersed element

An element that is generally too rare and unconcentrated to become an
essential constituent of a mineral, and that therefore occurs principally
as a substituent of the more abundant elements. AGI

dispersed pattern

In geochemical prospecting, a pattern or the distribution of the metal
content of soil, rock, water, or vegetation. AGI

disperse medium

Homogeneous phase (gas, liquid, or solid) through which particles are
dispersed to form a relatively stable sol. Mainly descriptive of colloidal
dispersion. See also:disperse system

disperse system

A two-phase system consisting of a dispersion medium and a dispersed
phase; a dispersion. Webster 3rd

dispersibility of dust

The ease with which dust is raised into suspension. Sinclair, 1

dispersing agent

a. A material that increases the stability of a suspension of particles in
a liquid medium by deflocculation of the primary particles.
Syn:deflocculating agent
b. Dispersant, deflocculating, or peptizing agent. One that acts to
prevent adherence of particles suspended in fluid, and delays
sedimentation. Pryor, 3
c. Reagents added to flotation circuits to prevent flocculation, esp. of
objectionable colloidal slimes. Sodium silicate is frequently added for
this purpose, and there is some indication that it has value in coal froth
flotation where a high percentage of clay slimes is present.
Mitchell

dispersion

a. The fairly permanent suspension of finely divided but undissolved
particles in a fluid. API, 1
b. The creation of a dispersion by deflocculation. BS, 5
c. The separation of polychromatic light (e.g., white light; sunlight)
into its component wavelengths.
d. The degree of inequality of refractive index and refraction of light of
various colors. Syn:refractive index
e. Change in the angle between optic axes in biaxial crystals due to
change in refractive indices with change in wavelength of light.
f. Change in the orientation of optical directions with respect to
crystallographic directions in monoclinic or triclinic minerals.
See also:index of refraction; optic axis.
g. Distortion of the shape of a seismic-wave train because of variation of
velocity with frequency.
h. Advance or recession of peaks and troughs from the beginning of the
seismic wave as it travels.
i. Breaking down or separation of soil aggregates into single grains.

dispersion halo

A region surrounding an ore deposit in which the ore-metal concentration
is intermediate between that of the ore and that of the country rock.
AGI

dispersion pattern

The pattern of distribution of chemical elements, esp. trace elements, in
the wall rocks of an orebody or in the surface materials surrounding it.
CF:aureole; halo. AGI

dispersoid

A body dispersed in a liquid.

disphenoid

a. In crystallography, a solid bounded by eight isosceles triangles.
Standard, 2
b. A closed crystal form of four faces, each an isosceles triangle and
derived from a bipyramid by suppressing alternate faces. It differs from a
tetrahedron, the four faces of which are equilateral triangles, by lower
symmetry. See also:sphenoid

displaced seam

A coal seam that has been dislocated by a fault. Nelson

displacement

a. The lateral movement of a point, usually at the surface, during
subsidence. Nelson
b. The volume displaced by the net area of the piston multiplied by the
length of the stroke. Lewis
c. Sometimes used as a syn. for offset deflection; deviation; dislocation;
throw. Long
d. A general term for the change in position of any point on one side of a
fault plane relative to any corresponding point on the opposite side of
the fault plane. Ballard
e. The capacity of an air compressor, usually expressed in cubic feet of
air per minute. Long
f. The word displacement should receive no technical meaning, but is
reserved for general use; it may be applied to a relative movement of the
two sides of the fault, measured in any direction, when that direction is
specified; for instance, the displacement of a stratum along a drift in a
mine would be the distance between the two sections of the stratum
measured along the drift. The word dislocation will also be most useful in
a general sense. Fay
g. The volume of liquid delivered by a single stroke of a pump piston.
Long
h. Any shift in the position of an image on a photograph that does not
alter the perspective characteristics of the photograph. It may be caused
by the relief of the objects photographed, the tilt of the photograph,
changes of scale, or atmospheric refraction. CF:distortion
i. A general term for the relative movement of the two sides of a fault,
measured in any chosen direction; also, the specific amount of such
movement. Syn:dislocation

displacement pump

One in which compressed air or steam, applied in pulses, drives out water
entering the pump chamber between pulses, a nonreturn valve preventing
reverse flow. Pryor, 3

displacement-type float

A device for measuring the liquid level in sumps or vessels. It consists
of a float, whose vertical height is greater than the level range being
measured and whose weight is such that it would sink in the fluid if not
supported. It is placed in a float chamber and supported in such a way
that as the liquid level rises around the displacer float it creates a
buoyant force equal to the weight of the liquid displaced. This force is
measured, and since it is proportional to level, the force measurement
becomes a level measurement. The device is used on sumps containing
high-gravity slurries. Nelson

displacive transformation

A change in crystal summetry as a result of changes in bond length or bond
angles (as contrasted to reconstructive transformations). The short-range
order is unchanged; the long-range order is changed.
CF:dilational transformation; reconstructive transformation;
rotational transformation. Van Vlack

disposable respirator

A respirator for which maintenance is not intended and that is designed to
be discarded after excessive resistance, sorbent exhaustion, physical
damage, or end-of-service-life renders it unsuitable for use. Examples of
this type of respirator are a disposable half-mask respirator or a
disposable escape-only self-contained breathing apparatus. ANSI

disrupted seam

A coal seam intersected by a fault or where its continuity is excessively
broken. Nelson

disruptive

Applied to that kind of force exerted by an explosive that tends to
shatter the rock into fragments. Fay

disseminated

Said of a mineral deposit (esp. of metals) in which the desired minerals
occur as scattered particles in the rock, but in sufficient quantity to
make the deposit an ore. Some disseminated deposits are very large.
CF:impregnated

disseminated crystals

Crystals that are found not attached to the mother rock, sometimes with
well-developed faces and doubly terminated.

disseminated deposit

A type of mineral deposit in which the minerals occur as small particles
or veinlets scattered through the country rock. Nelson

dissociation constant

The equilibrium constant for a dissociation reaction, defined as the
product of activities of the products of dissociation divided by the
activity of the original substance. When used for ionization reactions, it
is called an ionization constant; when it refers to a very slightly
soluble compound, it is called a solubility product. AGI

dissolution

a. The act or process of dissolving or breaking up, as a separation into
component parts. Webster 3rd
b. The taking up of a substance by a liquid with the formation of a
homogeneous solution. CTD

dissue

Corn. To break the rock from the walls of a rich lode in order to move the
ore without taking with it much gangue. Standard, 2

distance blocks

Wooden blocks placed in between the main spears and the side pump rods by
which the proper distance between them is adjusted. Fay

distance lag

In flotation, a delay attributable to the transport of material or the
finite rate of propagation of a signal or condition. Syn:velocity lag
Fuerstenau

distaxy

A mineral overgrowth not in crystallographic continuity with its core or
nucleus. CF:epitaxy; syntaxy.

disthene

A former name for kyanite.

disthenite

A metamorphic rock composed almost entirely of kyanite (disthene) and some
quartz, often associated with magnetiferous quartzite and amphibolite.
AGI

distillation

a. The process of decomposition whereby the original chitinous material of
certain fossils has lost its nitrogen, oxygen, and hydrogen, and is now
represented by a film of carbonaceous material. Syn. for carbonization.
AGI
b. The process of heating a substance to the temperature at which it is
converted to a vapor, then cooling the vapor, and thus restoring it to the
liquid state. See also:destructive distillation;
fractional distillation. Shell
c. A process of evaporation and recondensation used for separating liquids
into various fractions according to their boiling points or boiling
ranges. CTD

distillation furnace

A reverberatory heating furnace in which the charge is contained in a
closed vessel and does not come in contact with the flame. Fay

distinctive mineral

See:varietal mineral

distorted crystal

A crystal whose faces have developed unequally, some being larger than
others. Some distorted crystal forms are drawn out or shortened, but the
angle between the faces remains the same. See also:deformed crystal

distortion

a. The change in shape and size of a land area on a map due to the
flattening of the curved Earth surface to fit a plane. Distortion is
inevitable and is controlled in the development of a projection to produce
the characteristics of equal area, conformality, or equidistance.
AGI
b. Any shift in the position of an image on a photograph that alters the
perspective characteristics of the photograph. It may be caused by lens
aberration, differential shrinkage of film or paper, or motion of the film
or camera. CF:displacement

distortional wave

See:shear wave; S wave; transverse wave; secondary wave.

distributing magazine

A place or building, either near the mine entrance or underground, in
which explosives are stored for current use. Only one day's supply should
be kept at such points. The main supply of explosives is kept in a
magazine generally a safe distance from the mine or any mine buildings.
Kentucky

distribution curve

See:partition curve; Tromp distribution curve.

distribution factor

See:partition factor

distributive fault

See:step fault

distributive province

The environment embracing all rocks that contribute to the formation of a
contemporaneous sedimentary deposit, including the agents responsible for
their distribution. CF:provenance

distributor box

Box that receives feed from launder, pipe, or pump and splits it into
parallel mill circuits. Box attached to deck of shaking table, which
receives sands and distributes them along top of deck at feed end.
Pryor, 3

district

a. In the States and Territories of the United States west of the Missouri
River (prior to 1880), a vaguely bounded and temporary division and
organization made by the inhabitants of a mining region.
b. A limited area of underground workings. Nelson
c. A coal mine is generally divided into sections or districts for
purposes of ventilation and daily supervision. Nelson
d. An underground section of a coal mine served by its own roads and
ventilation ways; a section of a coal mine. CTD

disturbance

A term used by some geologists for a minor orogeny, e.g., the Palisades
disturbance. Schuchert (1924) used revolution for a major orogeny at the
end of an era, and disturbance for an orogeny within an era; this usage is
obsolete. AGI

disturbed area

An area where vegatation, topsoil, or overburden is removed or upon which
topsoil, spoil, coal processing waste, underground development waste, or
noncoal waste is placed by surface coal mining operations. Those areas are
classified as disturbed until reclamation is complete and the performance
bond or other assurance of performance is released.

disused workings

Workings that are no longer in operation but that are not classified as
abandoned. BS, 7

ditch

a. A drainage course in a mine. BCI
b. An artificial channel to convey water for use in mining. CF:flume
c. The drainage gutter along gangways and openings in anthracite mines.
d. In rotary drilling, a trough carrying mud to a screen.
Nichols, 1
e. The artificial course or trough in which the drill circulation fluid is
conducted from the collar of the borehole to the sump. To dump and discard
contents of a bailer, without taking a sample, into a ditch leading away
from the collar of a borehole. Syn:canal; chute; ditch. CF:trench
Long

ditch drain

A gutter excavated in the floor of a gangway or airway to carry the water
to the sump, or out to the surface.

ditcher

a. A mobile tracked machine fitted with an endless chain of buckets used
for shallow vertically sided trenching. Nelson
b. A drill mounted on a frame that rotates about a central axis. It is
used to cut circular trenches for the production of large grindstones.
Also called circle cutting drill. Fay

ditching

The digging or making of a ditch by the use of explosives.
See also:propagated blast

ditching dynamite

A nitroglycerin type explosive esp. designed to propagate sympathetically
from hole to hole in ditch blasting.

ditch water

The stale or stagnant water collected in a ditch.

ditch wiring

The method of connecting electric blasting caps in such a way that the two
free ends can be connected at one end of the line of holes. Fay

dithiocarbamate

A flotation collector agent of the general formula X2 N.CS.SM , X
being hydrogen, aryl, or alkyl radical. Pryor, 3

dithionate process

A process for extracting manganese from low-grade oxide ores. The
manganese ore is leached with dilute sulfur dioxide gas in the presence of
calcium dithionate solution, the manganese being recovered from solution
by precipitation with slaked lime and then nodulized or sintered.
Osborne

dithiophosphates

In mineral processing, flotation collector agents, marketed as Aerofloats
by the American Cyanamid Co.

dithizone

Diphenylthiocarbazone. Used in geochemical prospecting to detect traces of
certain metals. Pryor, 3

diurnal fluctuations

Variations occurring within a 24-h period and related to the rotation of
the earth. Hy

diurnal inequality

a. The departure easterly or westerly from the mean value of the
declination for the day. Mason
b. In tides, the difference in height and/or time of the two high waters
or of the two low waters of each day; also, the difference in velocity of
either of the two flood currents or of the two ebb currents of each day.
Hy

diurnal variation

a. The daily variation in the earth's magnetic field. AGI
b. In tides, having a period or cycle of approx. 1 lunar day (24.84 solar
hours). The tides and tidal currents are said to be diurnal when a single
flood and single ebb occur each lunar day. Hy

diver

Small plummet, so adjusted as to density that by rising or falling it can
be used to show whether specific gravity of pulp is above or below a
desired control point. If pulp is opaque, diver can initiate magnetic
signal, or in a pulp containing magnetic material can carry radioactive
marking material. Pryor, 3

diversion valve

A valve that permits flow to be directed into any one of two or more
pipes. Nichols, 1

diversity factor

The ratio of the sum of the individual maximum loads during a period to
the simultaneous maximum loads of all the same units during the same
period. Always unity or more. Strock, 2

divided cell

A cell containing a diaphragm or other means for physically separating the
anolyte and catholyte. Lowenheim

divider

Cross-steel or timber piece in a circular or rectangular shaft. Such
pieces serve to divide the shaft into compartments and may also carry the
cage guides, etc. See also:bunton

diviner

Dowser. AGI

diving bell

A watertight, bell-shaped steel chamber that can be lowered to or raised
from a freshwater or seawater bed by a crane. It is open at the bottom and
filled with compressed air, so that persons can prepare foundations and
undertake similar construction work underwater. Hammond

divining

A method of searching for water or minerals by holding a hazel fork (or
other device) in the hands, and the free end is said to bend downward when
a discovery is made. In the Middle Ages, the divining rod was closely
associated with the mine surveying profession. The water diviner has not
succeeded when submitted to impartial scientific tests. Nelson

divining rod

Traditionally, a forked wooden stick, cut from a willow or other
water-loving plant, used in dowsing. It supposedly dips downward sharply
when held over a body of ground water or a mineral deposit, thus revealing
the presence of these substances. Syn:witching stick; wiggle stick;
dowsing rod; twig. CF:water witch; waterfinder. AGI

divisional plane

A general term that includes joints, cleavage, faults, bedding planes, and
other surfaces of separation. AGI

division method

One of three recognized methods for determining the average velocity of
airflow in a mine roadway by anemometer. This is the precise method of
determining the mean velocity of the air current. CF:single-spot method;
traversing method.

dixanthogen

A breakdown product of xanthate collectors (flotation agents) with some
residual value for that purpose. Pryor, 3

dixenite

A trigonal mineral, CuMn14 Fe(AsO3 )5 (SiO4 )
2 (AsO4 )(OH)6 ; forms nearly black aggregates of thin
folia; at Laangban, Sweden.

djalmaite

A former name for uranmicrolite. See also:microlite

djurleite

A monoclinic mineral, Cu31 S16 ; X-ray pattern is similar
to, but distinct from, chalcocite.

D.L.T. reagents

Condensation products of ethanolamine and higher fatty acids, used as
flotation agents (collectors). Pryor, 3

dneprovskite

See:wood tin

dobie man

See:blaster

Dobson prop

A hydraulic prop that is basically a self-contained hydraulic jack with an
integral pump unit built into the prop. It is designed to yield at 25 st
(22.7 t) and has a setting load of 6 st (5.4 t). Nelson

Dobson support system

A self-advancing support for use on long-wall faces. One unit embodies
three props. The front prop, which is attached to the face conveyor,
carries two roof bars side by side that give cantilever support over the
conveyor track. The two rear props are mounted on a common floor bar and
carry a single roof bar that passes between the two front bars. The front
prop is attached to the rear structure only by the advancing ram within
the box structure of the floor bar. Nelson

docket

A pay ticket containing particulars of shifts worked, coal filled, yardage
driven, and other work done, including the total wages less deductions.
Nelson

doctor

a. To treat a poor-quality carbon with substances such as oil, wax,
gutta-percha, solder, gum, or resin, to camouflage its defects, hence
changing its appearance to make it look like a better grade stone. Also
called dope. Long
b. A makeshift, temporary repair. Long
c. As used in the mining industry, to salt. Long

Dodd buddle

A round table resembling in operation a Wilfley table, and also like the
Pinder concentrator except that it is convex instead of concave. The table
does not revolve but has a peripheral jerking motion imparted to it
circumferentially by means of a toggle movement. Liddell

dodecahedral cleavage

In isometric minerals, a cleavage parallel to the faces of a rhombic
dodecahedron 110 , e.g., sphalerite.

dodecahedron

a. An isometric form composed of 12 equal rhombic faces, each parallel to
1 axis and intersecting the other 2 axes at equal distances, specif. named
the rhombic dodecahedron. See also:pyritohedron
b. Any solid with 12 symmetrically equivalent faces, e.g. deltoid;
pyritohedron.
c. The isometric form 110 , the rhombic dodecahedron.
d. Brazilian diamonds with the dodecahedral form, also called Brazilian
stone.

dodecant

Each 12th of crystal space defined by a trigonal or hexagonal c axis and
its orthogonal three coplanar a axes. CF:octant

Dodge crusher

Similar to the Blake crusher, except the movable jaw is hinged at the
bottom. Therefore the discharge opening is fixed, giving a more uniform
product than the Blake with its discharge opening varying every stroke.
This type of jaw crusher gives the greatest movement on the largest lump.
Liddell

Dodge pulverizer

A hexagonal barrel revolving on a horizontal axis, containing perforated
die plates and screens. Pulverizing is done by steel balls inside the
barrel. Liddell

dog

a. An iron bar, spiked at the ends, with which timbers are held together
and steadied.
b. A short, heavy iron bar, used as a drag behind a car or trip of cars
when ascending a slope to prevent them running back down the slope in case
of an accident; a drag.
c. See:casing dog
d. A trigger that limits the advance of a traversing table.
ACSG, 2
e. Any of various devices for holding, gripping, or fastening something.
See also:chair; dog; catch; wing. Webster 3rd
f. A drag for the wheel of a vehicle. Webster 3rd
g. A device attached to the workpiece by means of which the work is
revolved. ACSG, 2

dog-and-chain

An iron lever with a chain attached by which props are withdrawn.
Fay

dogger

a. A large, irregular nodule, usually of clay ironstone, sometimes
containing fossils, found in a sedimentary rock, as in the Jurassic rocks
of Yorkshire, England. AGI
b. An English term for any large, lumpy mass of sandstone longer than it
is broad, with steep rounded sides. AGI

doghole

A small opening from one place in a coal mine to another; smaller than a
breakthrough. Syn:monkey hole

doghole mine

Name applied to small coal mines that employ fewer than 15 miners. The
so-called dogholes are most numerous in Kentucky, but there are many in
Virginia and West Virginia.

dogholes

See:doghole mine

dog hook

a. A strong hook or wrench for separating iron boring rods. Fay
b. An iron bar with a bent prong used in handling logs. Fay

doghouse

a. The structure enclosing the drill platform and machine. Long
b. A small shelter in which members of a drill crew change clothing.
CF:changehouse
c. See:forechamber
d. Any enclosure or small chamber in a mine used for storage or resting.

dog iron

A short bar of iron with both ends pointed and bent down so as to hold
together two pieces of wood into which the points are driven; or one end
may be bent down and pointed, while the other is formed into an eye, so
that if the point be driven into a log, the other end may be used to haul
on. Zern

dogleg

a. An abrupt angular change in course or direction, as of a borehole or in
a survey traverse. Also, a deflected borehole, survey course, or anything
with an abrupt change in direction resembling the hind leg of a dog.
AGI
b. An abrupt bend or kink in a wire rope or cable. Long
c. An abrupt bend in a path, piping system, or road. Long

dogleg severity

Same as deflection angle; hole curvature. Long

dogs

a. Eng. In the plural; bits of wood at the bottom of an air door.
Fay
b. See also:dog

dog spike

A spike generally used to fasten rails to the sleepers when laying track.
Their length should be 1/2 in (1.27 cm) less than the depth of the sleeper
into which they are being pounded. Sinclair, 5

dog-tooth spar

Calcite with sharp scalenohedral termination.

dogtooth spar

Calcite in acute scalenohedral crystals facing like dogs' teeth into an
open cavity or vein. See also:scalenohedron

doit

Eng. Foulness, or damp air. Fay

dole

A division of a parcel of ore. Also spelled dol. Fay

dolerite

a. In the United States, a syn. of diabase. AGI
b. In British usage, the preferred term for what is called diabase in the
United States. Etymol: Greek doleros, "deceitful," in reference to the
fine-grained character of the rock that makes it difficult to identify
megascopically. CF:diorite; trap. Syn:whin

doleritic

a. Of or pertaining to dolerite. See also:ophitic
b. A preferred syn. of ophitic in European usage. AGI

dolerophanite

A monoclinic mineral, Cu2 (SO4 )O ; brown; reported at Mt.
Vesuvius. Also spelled dolerophane.

dolina

See:doline

doline

A syn. of sinkhole. Also spelled: dolina. Etymol: German transliteration
from Slovene "dolina," "valley." AGI

dollie

See:dolly

dolly

a. A trucklike platform, with an attached roller, used in shifting heavy
loads.
b. A counterbalance weight sometimes used in a hoisting shaft.
Nelson
c. To break up quartz with a piece of wood shod with iron, in order to be
able to wash out the gold. Fay
d. A tool used to sharpen drills. Stauffer
e. See:car
concentrate the ore by the tossing and packing process.
See also:dolly tub

dolly tub

A large wooden tub used for the final washing of valuable minerals
separated by water concentration in ore dressing. See also:tossing;
dolly. CTD

dolly wheels

Pairs of wheels used to support rods of a Cornish pump working on a slope.
Pryor, 3

doloma

Calcined dolomite, that is a mixture of the oxides CaO and MgO.
Dodd

dolomite

a. A trigonal mineral, [CaMg(CO3 )2 ] ; forms saddle-shaped
rhombohedra having rhombohedral cleavage; white to pale tints; in large
beds as dolostone and dolomitic marble, also in veins and in serpentinite;
a source of magnesium and dimension stone. Syn:bitter spar; pearl spar;
magnesian spar; rhomb spar.
b. The mineral group ankerite, dolomite, kutnohorite, minrecordite, and
norsethite.
c. A carbonate sedimentary rock consisting of more than 50% to 90% mineral
dolomite, depending upon classifier, or having a Ca:Mg ratio in the range
1.5 to 1.7, or having an MgO equivalent of 19.5% to 21.6%, or having a
magnesium-carbonate equivalent of 41.0% to 45.4%. Dolomite beds are
associated and interbedded with limestone, commonly representing
postdepositional replacement of limestone. Syn:dolostone;
dolomite rock.

dolomite limestone

See:dolomitic limestone

dolomite marble

A crystalline variety of limestone, containing in excess of 40% of
magnesium carbonate as the dolomite constituent.

dolomite rock

See:dolomite

dolomitic

a. Dolomite-bearing, or containing dolomite; esp. said of a rock that
contains 5% to 50% of the mineral dolomite in the form of cement and/or
grains or crystals. AGI
b. Containing magnesium; e.g., dolomitic lime containing 30% to 50%
magnesium. AGI

dolomitic limestone

a. A limestone that has been incompletely dolomitized. AGI
b. A limestone in which the mineral dolomite is conspicuous, but less
abundant than calcite. Syn:dolomite limestone
CF:magnesian limestone

dolomitization

The process by which limestone is wholly or partly converted to dolomite
rock or dolomitic limestone by the replacement of the original calcium
carbonate (calcite) by magnesium carbonate (mineral dolomite), usually
through the action of magnesium-bearing water (seawater or percolating
meteoric water). It can occur penecontemporaneously or shortly after
deposition of the limestone, or during lithification at a later period.
Syn:dolomization

dolomization

See:dolomitization

doloresite

A monoclinic mineral, H8 V6 O16 ; an alteration
product of montroseite in sandstone from the Colorado Plateau; named for
the Dolores River, CO.

dolostone

A term applied by some petrologists to rock consisting primarily of the
mineral dolomite. Syn:dolomite

dolphin

A fixed mooring in the open sea formed of a number of piles, or a guide
for ships entering a narrow harbor mouth. Hammond

domain

a. A substructure in a ferromagnetic material within which all of the
elementary magnets (electron spins) are held aligned in one direction by
interatomic forces; if isolated, a domain would be a saturated permanent
magnet. ASM, 1
b. A region within a grain of magnetically ordered mineral, within which
the spontaneous magnetization has a constant value characteristic of the
mineral composition and temperature. Syn:magnetic domain

dome

a. Roof of a furnace that is roughly hemispherical in shape.
b. The steam chamber of a boiler. CF:air dome
c. An uplift or anticlinal structure, either circular or elliptical in
outline, in which the rocks dip gently away in all directions. A dome may
be small, such as a Gulf Coast salt dome, or many kilometers in diameter.
Domes include diapirs, volcanic domes, and cratonic uplifts. Type
structure: Nashville Dome, TN. See also:pericline; arch; salt dome.
Syn:dome structure; structural dome; quaquaversal fold. Less-preferred
syn: swell. CF:basin
d. A general term for any smoothly rounded landform or rock mass, such as
a rock-capped mountain summit, that roughly resembles the dome of a
building; e.g., the rounded granite peaks of Yosemite, CA. The term is
also applied to broadly up-arched regions, such as the English Lake
District or the Black Hills of South Dakota. AGI
e. A large magmatic or migmatitic intrusion whose surface is convex upward
and whose sides slope away at low but gradually increasing angles.
Intrusive igneous domes include laccoliths and batholiths; the term is
used when the evidence as to the character of the lower parts of the
intrusion is insufficient to allow more specific identification.
AGI
f. An open crystal form of four parallel faces that intersect the c axis
and one other; incorrectly called a horizontal prism. Adj. domatic.
g. A symmetrical structural uplift having an approx. circular outline in
plan view, and in which the uplifted beds dip outward more or less equally
in all directions from the center, which is both the highest point of the
structure and locally of the uplifted beds.
h. A mountain having a smoothly rounded summit of rock that resembles the
cupola or dome on a building. AGI
i. An open crystal form consisting of two parallel faces that truncate the
intersections of two sets of pinacoids and are astride a symmetry plane.

domestic coal

a. Coal for use around colliery in miners' houses or for local sale.
Zern
b. Sized coal for use in houses. See also:house coal
c. Coal used in country of origin; not for foreign consumption.
Zern

domestic sampling

Routine sampling by mine officials for systematic control of mining
operations. See also:development sampling

dome structure

See:dome

dome theory

A theory that strata movements caused by underground excavations were
limited by a kind of dome that had for its base the area of excavation,
and that the movements diminished as they extended upward from the center
of the area. See also:harmless depth theory; normal theory.
Nelson

domeykite

An isometric mineral, Cu3 As; forms reniform and botryoidal masses
and disseminated grains. See also:white copper

dominant vitrain

A field term to denote, in accordance with an arbitrary scale established
for use in describing banded coal, a frequency of occurrence of vitrain
bands comprising more than 60% of the total coal layer.
CF:abundant vitrain; moderate vitrain; sparse vitrain. AGI

donarite

An explosive consisting of 70% ammonium nitrate, 25% trinitrotoluol, and
5% nitroglycerin. Hackh

donbassite

A possible mineral species in the chlorite group.

donkey engineer

In anthracite and bituminous coal mining, a general term for the attendant
of a small auxiliary engine, powered by steam or compressed air, used to
drive pumps to drain sumps (pits in which excess water is collected) or
supply water to boilers, or to operate a hoist for a shallow shaft. Also
called donkey runner. DOT

donkey hoist

A small auxiliary hoisting drum and engine operated by steam, by
compressed air, and sometimes by an electric motor or an
internal-combustion engine. Long

donkey pump

Any of several kinds of combined pump and steam engine. It may be operated
independently of the engine; used to supply water to a boiler, drain
sumps, etc.

donkey runner

See:donkey engineer

donor

An exploding charge producing an impulse that impinges upon an explosive
acceptor charge. Meyer

doodlebug

a. The essential treatment plant of a small dredge set on a pontoon. There
is usually a hopper into which the dragline dumps its spoil and which may
have a grizzly arrangement, according to the nature of the gravel. A water
supply washes the contents of the hopper into a revolving screen, feeding
the fines over riffled tables and rejecting the stones and oversize by
means of a stacker. This treatment plant or washing unit can be floated in
the excavation dug by a dragline and is the ideal unit to install when
small-scale operations are to be carried out below water level or where it
is not necessary to use dry opencast paddock methods. Harrison
b. Any one of a large number of unscientific devices with which it is
claimed water, mineral, and oil deposits can be located. AGI
c. A popular term for any of various kinds of geophysical prospecting
equipment.

dook

a. Scot. A mine or roadway driven to the dip, usually the main road.
See also:slope
b. Som. An underground inclined plane.

door

A hinged or sliding frame or piece of wood, metal, stone or other
material, generally rectangular, used for closing or opening an entrance
or exit. Doors are placed in air passages of mines to prevent the
ventilating current from taking a short cut to the upcast shaft, and to
direct the current to the working face. See also:air door;
ventilation doors. Standard, 2

door boy

See:trapper

doorheads

Scot. The roof or top of the workings at a shaft.

door tender

One whose duty it is to open and close a mine door before and after the
passage of a train of mine cars; a trapper. Zern

door trapper

See:door tender

door-type sampler

A soil-sampling tube or barrel equipped with an auger-type cutting shoe
and made to be rotated to obtain samples of sand, gravel, and other
granular material. The body of the sampler is essentially a tube in which
a small opening or window is machined and equipped with a covering, which
can be latched shut while the sample is being taken. When the sampler is
removed from the ground, the latch is released and the sample removed
through the door or window. Syn:window-type sample

dope

a. Individual, dry, nonexplosive ingredients that comprise a portion of an
explosive formulation.
b. Absorbent material, as sawdust, infusorial earth, mica, etc., used in
certain manufacturing processes, as in making dynamite.
Webster 2nd
c. Heavy grease or other material used to protect or lubricate drill rods
and/or open gears, chain and sprockets, etc. Also called gunk; rod dope;
rod grease. Long
d. To apply a lubricant to drill rods, rod couplings, open gears, etc.
Long
e. To doctor a drill diamond. See also:doctor
f. A rubberlike compound applied to granite surfaces before inscriptions
are cut in the granite. AIME, 1
g. A viscous liquid put on pipe threads to make a tight joint.
Nichols, 1
h. Slang for mold lubricant. ASTM

Doppler

A self-contained electronic system that makes use of Doppler's principle
of frequency shift of waves emanating from a moving source. In this
system, a pulsed or continuous wave is sent diagonally downward fore and
aft, forward and backward, and the frequencies are compared in order to
obtain the true ground speed. The heading is obtained from a special
magnetic compass and is maintained by a directional gyro used as an
integrating device. The distance thus determined has a precision better
than one part in a thousand, which is sufficient for most geophysical
surveys. Dobrin

dopplerite

a. A black gelatinous matter in peat and soft brown coal consisting of
humic acids or their salts; has a detrimental effect on briquettes and
coke. Syn:torf-dopplerit; trof-dopplerit; Weichbraunkohlen-dopplerit;
peat gel; brown-coal gel.
b. A gel in peat composed of ulmins derived from plant carbohydrates by
bacterial destruction of proteins.
c. An asphalt found in New Zealand and parts of Siberia.

dopplerite sapropel

A variety of sapropel that contains much humic acid. Tomkeieff

dore

Gold and silver bullion that remains in a cupelling furnace after the lead
has been oxidized and skimmed off. Syn:dore bullion

dore bullion

See:dore

dore metal

See:dore silver

dore silver

Crude silver containing a small amount of gold, obtained after removing
lead in a cupelling furnace. Syn:dore bullion; dore metal.

dornick

a. A piece of rock of approx. fist size.
b. A boulder of iron ore.

Dorr mill

A tube mill designed for operation as a closed-circuit wet-grinding unit.
See also:tube mill

Dorr rake classifier

A mechanical classifier consisting of an inclined settling tank and a
rake-type conveying agitating mechanism. Feed introduced at the low end of
the tank flows over a distributing apron toward the high end of the tank.
The heavier materials of sand size settle into the rake zone and are raked
up the slope and out the tank; slime and finer sands are carried over the
rear wall in suspension. Taggart, 2

Dosco miner

A heavy, crawler-tracked, 200-hp (149-kW) cutter loader designed for
longwall faces in seams over 4-1/2 ft (1.37 m) thick, and takes a buttock
5 ft (1.52 m) wide. The maximum cutting height is 7-1/2 ft (2.29 m).
Dimensions: length 17-3/4 ft (5.41 m), width 4-1/2 ft (1.37 m), and height
3-3/4 ft (1.14 m). The cutterhead consists of seven cutter chains mounted
side by side and can be moved up and down radially to cut the coal from
roof to floor. It delivers the coal onto the face conveyor by a short
cross conveyor. Capacity is more than 400 st (363 t) per machine and more
than 4 st (3.63 t) output per worker per shift. Nelson

dose

a. A special charge used in a blast furnace, designed to cure furnace
troubles. Fay
b. The amount of ionizing radiation energy absorbed per unit mass of
irradiated material at a specific location, such as a part of the human
body. Measured in reps, rems, and rads. Lyman

dot chart

a. A graphic aid used in the correction of station gravity for terrain
effect, or for computing gravity effects of irregular masses. It can also
be used in magnetic interpretation. AGI
b. A transparent graph-type chart used in the calculation of the gravity
effects of various structures. The dots on the chart represent unit areas.
AGI

double

In rotary drilling, two pieces of drill rod left fastened together during
raising and lowering. Also called couple; couplet. Nichols, 1

double

A. One of several terms (or letter symbols) used to designate
medium-quality drill diamonds. Long

double-acting pump

Scot. A pump that discharges at both forward and backward stroke.

double-acting ram

See:two-way ram

double-action press

A press handling two operations each revolution. It carries two rams, one
inside the other, so actuated that one motion immediately follows the
other. Crispin

double-action pump

A pump whose water cylinders are equipped with intake and discharge valves
at each end; hence liquid is delivered by the pump on both the forward and
the backward strokes of the pump piston. Long

double bank

a. To take up a claim parallel with and adjoining another claim containing
an auriferous vein or deposit. Fay
b. Working with double sets or relays of persons. Fay

double block

a. A pair of multiple-sheave blocks reeved with rope or lines; a block and
tackle. Long
b. Two pulleys or small sheaves mounted on a single shaft within a frame
or shell. Long

double-burned

Burned at a high temperature. This does not mean two firings. AISI

double-burned dolomite

a. Dolomite, with additions of oxides of iron, burned at a high
temperature. This does not mean two firings. ARI
b. Clinkered dolomite. AISI

double core barrel

A core barrel with an inner tube to hold the core. The inner tube does not
rotate during drilling, thereby giving a better core recovery.
Syn:double-tube core barrel

double crib

Eng. Two crib sets are placed back to back to form a two-compartment
crib-lined raise. This technique is employed in weak ground in place of a
double compartment separated by only a single dividing member.

double-cut sprocket

For double-pitch roller chains, a sprocket having two sets of effective
teeth. Tooth spaces for the second set are located midway between those of
the first set. Jackson, 1

double-deck gangway

A method of silling or working out 10 ft (3 m) or so above the haulage
level and forming a double-deck gangway. Chutes are constructed at
intervals for ore transfer into mine cars. Nelson

double-double unit conveyor

A longwall conveyor layout in which the center or main gate serves two
double units, one on each side. The gate belts from each double unit
deliver the coal onto cross-gate belts, which in turn deliver to the main
gate conveyor and then by trunk conveyor or cars to the pit bottom.
Nelson

double drum

Hoisting device having two cable spools or drums rotating in opposite
directions. Long

double-drum hoist

A hoist with two drums that can be driven separately or together by a
clutch. See also:main-and-tail haulage

double-duo mill

Has two pairs of rolls, mounted in one stand, one pair of rolls being
higher than, and in advance of the other. Osborne

double-ended

A term applied to any cutter loader that can cut both ways on a longwall
face without turning at each end. This requires cutting units at both ends
of the machine and duplication of other essential parts. Nelson

double-ended pick

A diamond-shaped coal-cutter pick that is held in a special holder and
chain. Both ends of the pick are used and then discarded. The type is used
widely in the United States. See also:coal-cutter pick

double-engine plane

Loads are raised or lowered on a slope by a stationary engine and wire
rope, as in an inclined shaft. There is a double track, or three rails and
turnout; the descending trip assists the engine to raise the ascending
trip, thus eliminating dead load, except rope. Peele

double entry

a. A pair of entries in flat or gently dipping coal so laid out that rooms
can be driven from both entries; twin entries. See also:entry
Fay
b. A system of ventilation by which the air current is brought into the
rooms through one entry and out through a parallel entry or air course.
Fay
c. See:main entry

double-entry room-and-pillar mining

See:room-and-pillar

double-entry zone test

A test in which coal dust is placed in each of two connected parallel
entries. Rice, 2

doubleheader

Applied to quarry equipment consisting of two independent channeling
machines on a single truck, operated by one person.

double headings

The driving of two coal headings, parallel and side by side, for
development purposes. Usually a pillar 10 to 20 yd (9.14 to 18.29 m) wide
is left between them. Formerly it was the practice at many coal mines to
drive only one heading from which the stalls were turned off right and
left. Two headings simplify ventilation and provide a second egress in an
emergency. Nelson

double helical bag conveyor

Closely spaced parallel tubes with right- and left-hand rounded helical
threads rotating in opposite directions, on which bags or other objects
are carried while being conveyed. Syn:helical bag conveyor

double-inlet fan

A centrifugal fan in which air enters the impeller on both sides. Also
called double-width fan. BS, 8

double jack

a. A two-hand heavy hammer, usually weighing about 10 lb (4.54 kg).
CF:single jack
b. A double or twin-screw drill column. Long

double jigback

An aerial ropeway in which two parallel track ropes are used, each
carrying a carriage. Nelson

double-leg bucket elevator

A type of bucket elevator having the carrying and return runs enclosed in
separate casings between the head and boot. See also:bucket elevator

double leg en masse conveyor

A conveyor or elevator in which the carrying and return runs are operated
in separated parallel and adjacent casings.

double load

A charge in a borehole separated by a quantity of inert material for the
purpose of distributing the effect, or for preventing part of the charge
blowing out at a seam or fissure, in which case the inert material is
placed so as to include the seam. Fay

double packing

A form of strip packing that removes the localized high roof pressure from
the vicinity of a roadway into a region in the goaf. It consists of two
parallel packs adjacent to, and on each side of, the roadway, with the
packs immediately at the roadsides built of such a width as to offer less
resistance than wider and stronger packs (called buttress packs) more
remote from the roadway. The principle of double packing was developed by
D.W. Phillips in Great Britain. See also:gate side pack; strip packing;
yield-pillar system. CF:single packing

double parting

A bypass for mine cars. See also:junction

double-pitch roller chain

A roller chain having double the pitch of a standard roller chain, but
otherwise having standard pins, bushings, and rollers. Jackson, 1

double-pulley-drive conveyor

A conveyor in which power is transmitted to the belt by two pulleys.
NEMA, 2

double-refracting spar

See:Iceland spar

double refraction

Refraction shown by certain crystals that split the incident ray into two
refracted rays, polarized in perpendicular planes.
See also:birefringence

double-roll breaker

a. A coalbreaker that relies on the impact of special teeth for the bulk
of reducing, rather than on the compression between the rolls. An
important feature is adjustment, which may be made during operation. The
machines are flexible enough to produce top size ranging from 6 to 14 in
(15.4 to 35.56 cm). Mitchell
b. See:double-roll crusher

double-roll crusher

A machine for breaking down ore, rock, or coal and to discharge the
crushed material below. See also:spring-roll crusher; roll crusher;
single-roll crusher. Nelson

double-roll press

A press in which pressure is applied by the mating of one or more pairs of
indented rolls of equal diameter, revolving in opposite directions.
Syn:Belgian press

double-room system

See:room-and-pillar

double-round nose

The cross-sectional view of the cutting face portion of a coring bit when
its profile is a full half circle, the radius of which is one-half the
wall thickness or kerf of the bit face. CF:single-round nose
Long

double setting

A leveling procedure whereby observations are duplicated by resetting the
instrument to detect errors of measurement immediately. Also called dual
setting. BS, 7

double-shift places

At collieries where there is only one recognized coal-winning shift in 24
h, it is a general practice to have double shifts (and sometimes treble)
of workers in development headings that require a speedy advance.
Nelson

double-spaced neutron log

This method employs two neutron logging tools with different spacings
between the source and the detector or two detectors in the same tool at
different spacings. The spacings usually differ by 6 to 10 in (15.24 to
25.4 cm). The long-spaced log is run slowly and with a large time constant
so that its statistical variation is not excessive, for the counting rate
is much lower than that of the regular-spaced log. This technique has
proved to be a potent technique for discriminating gas sands from oil
sands in Venezuela. Wyllie

double spiral cut

A cylindrical drill-round cut whose spiral hole pattern gives the widest
opening and permits opposite holes to be ignited successfully. This gives
the best cleaning of the opening and safety in the advance is increased,
since one section of the double spiral can give breakage irrespective of
the other. Langefors

double stall

An earlier system of working thick seams in South Wales. Two narrow stalls
are turned off the heading and after advancing some 8 to 12 yd (7.32 to
10.97 m) (so as to leave a pillar of coal next to the heading) are
connected and the coal between them worked as a single face. Double stalls
are intermediate between pillar-and-stall and longwall. Nelson

doublet

An assembled gem substitute composed of two pieces of material fused or
cemented together. If both parts are of the species being imitated, it is
a genuine doublet; if one part, it is a semigenuine doublet; if it
contains no parts of the species being imitated, it is a false doublet; or
if no part is a mineral, it is an imitation doublet. CF:triplet

double-track portable switch

A tub-changing arrangement for a tunnel face. The double-track loop is
superimposed on the tunnel track and equipped with ramps, clamps, and
spring switches so arranged that the loaded cars take one track outward
while the empties take the other track inward. Syn:portable shunt
Nelson

double-trolley system

A system of electric traction where, instead of the running rails, a
second insulated contact wire is used for the return or negative current.
CTD

double-tube core barrel

A double-tube core barrel having the upper end of the inner tube coupled
to the core-barrel head by means of an antifriction device, such as a
roller or ball bearing; hence, the inner tube tends to remain stationary
when the outer tube, which is rigidly coupled to the core-barrel head, is
rotated. Long

double-unit conveyor

A longwall conveyor layout from 200 to 280 yd (183 to 256 m) long,
developed between two tailgates with a main gate in the center of the
face. The main gate conveyor is served by two face conveyors and may act
as an intake or a return airway. The tailgates may serve as supply roads.
See also:double-double unit conveyor; main gate. Nelson

double wedge cut

A drill-hole pattern consisting of a shallow wedge within an outer wedge,
which is often used to obtain deep pull in hard rock.
See also:wedge cut

double wicket

A method of working in which rooms are driven from adjacent headings to
meet at their extremities. Zern

double working

N. of Eng. Two hewers (miners) working together in the same heading.
Syn:hewing double

doubly plunging fold

A fold that plunges in opposite directions from a central point. In a
doubly plunging anticline, the plunge is away from this point; in a doubly
plunging syncline, the plunge is toward this point. Billings

doubly refractive

Causing double refraction. See also:birefringent

dough

Alternate spelling of daugh.

doughnut

The cylinder of coal formed by a coal auger. Nelson

Douglas furnace

A horizontal, revolving cylindrical furnace having a central flue.
Fay

Douglas process

See:Hunt and Douglas process

douk

Eng. A soft dark clay found in veins. Probably derived from the Saxon
deagan, meaning to knead or mix with water. Syn:dowk

dousing

See:dowsing

dousing rod

Commonly used by drillers as a name applied to a wooden wand, rod, forked
tree limb, or twig (usually witch hazel) supposedly useful in locating
formations bearing water, oil, or mineral. Also called divining rod;
doodlebug; dowsing rod. Long

doverite

See:synchysite

Dow cell

The Dow electrolytic cell is a steel shell about 16 ft (4.88 m) long, 5 ft
(1.52 m) wide, and 6 ft (1.83 m) deep. The electrolyte contains about 60%
NaCl, 15% CaCl2 , and 25% MgCl2 ; it is maintained at a
temperature of 700 to 750 degrees C by controlled firing underneath the
cell. Newton, 1

dowk

See:douk

downbuckle

See:tectogene

downcast

a. The shaft through which the fresh air is drawn or forced into the mine;
the intake. See also:air shaft; intake. Fay
b. That side of a fault on which the strata have been displaced downward
in relation to the upthrow or upcast side. CTD

downcast shaft

The shaft down which the fresh air enters the mine or workings.
See also:upcast shaft

downcomer

A pipe to conduct something downward, such as: (1) a pipe for leading the
hot gases from the top of a blast furnace downward to the dust collectors
and flue system, and (2) a tube larger in diameter than the water tubes in
some water-tube boilers for conducting water from each top drum to a
bottom drum under the influence of thermal circulation.
Webster 3rd

downdip

Parallel to or in general direction of the dip of a bed, rock stratum, or
vein. Long

downdraft

A downward current of air or other gas (as in a mine shaft, kiln, or
carburetor). Syn:downcast

downdrift

In a mine drift, the direction of predominant water movement.

downhole

a. A borehole drilled at any angle inclined downward in a direction below
the horizon.
b. adj. In a borehole; e.g., downhole equipment.--adv. Deeper; e.g., to
perforate downhole. AGI

downline

A line of detonating cord or plastic tubing in a blast hole that transmits
the detonation from the trunkline or surface delay system down the hole to
the primer.

downslope

The land surface between the projected outcrop of the lowest coalbed being
mined along each highwall and a valley floor.

downspouts

Lanc. Pipes fixed down the side of a shaft for conducting water from one
level or sump to another.

downstream face

The dry side of a dam. Nichols, 1

down-the-hole drill

A percussive or hammer drill in which the bit-driven mechanism is located
immediately behind the drill bit and is small enough in diameter to permit
it to enter and follow the bit down into the hole drilled.

down-the-hole extensometer

A device used to measure differential strains in a drill hole.

downthrow

a. The downthrown side of a fault. AGI
b. The amount of downward vertical displacement of a fault. CF:upthrow;
heave. AGI

downthrow fault

A fault that displaces the strata downward relative to the workings
approaching it. It would be an upthrow fault to workings on the opposite
side.

downthrow side

The lower side of a fault.

Downtonian

Uppermost Silurian or lowermost Devonian. AGI

downward continuation

a. Interpretation method in which the values of a component of the
magnetic field at lower levels are computed from the values at the
surface. Schieferdecker
b. The process of determining, from values measured at one level, the
value of a potential (e.g., gravitational) field at a lower level.
AGI

downward course

In mining, the course of the vein from the surface downward. Also called
course downward.

downward enrichment

See:supergene enrichment

downward percolation

See:sand leaching

Dow process

A process for the production of magnesium by electrolysis of molten
magnesium chloride. ASM, 1

dowsing

The practice of locating ground water, mineral deposits, or other objects
by means of a divining rod or a pendulum. A dowser may claim also to be
able to diagnose diseases, determine the sex of unborn babies, etc.
Syn:dousing; water witching. CF:rhabdomancy

dowsing rod

See:divining rod

Dowson gas

A mixture of producer gas and water gas obtained by passing steam and air
over heated coal or coke in a Dowson producer.

Dowson producer

A furnace used for the manufacture of producer gas. Fay

Dowty hydraulic tub retarder

A retarder that consists of lengths of steel channel with attached rubbing
strips that operate on the face of the wheels above center. The action is
controlled by a hydraulic cylinder containing opposed pistons. The
hydraulic pressure is supplied from an accumulator in which pressure is
maintained by means of a 5-hp (3.7-kW) electric motor-driven pump that is
sufficient for 10 retarder unit. Mason

Dowty prop

A prop that is in effect a self-contained hydraulic jack consisting of two
tubes, the upper one telescoping into the lower. The upper (or inner) tube
acts both as a reservoir for the oil and as a container for the pump,
yield valve, and other accessories. Nelson

Dowty roofmaster

A self-contained, oil-operated steel support for use on a mechanized
long-wall face. It has support frames constructed of rigid roof and floor
members supported by yielding hydraulic props. Two- and three-prop units
are connected alternately to the armored conveyor by means of jacks
mounted in the floor members, to carry long and short cantilever roof
beams, respectively. See also:self-advancing supports

dozer

Abbrev. for bulldozer; shovel dozer. See also:bulldozer
Nichols, 2

dozer shovel

A tractor equipped with a front-mounted bucket that can be used for
pushing, digging, and truckloading. Nelson

dozzle

See:core.

D.P. reagents

Flotation reagents made by DuPont are D.P. 243, a 50% aqueous paste of
lorolamine (lorol being a mixture of primary straight-chain alcohols) and
D.P.Q., lauryl trimethyl ammonium bromide. Others include D.P.Q.B.,
D.P.C., D.P.N., and D.P.L.A. Pryor, 3

dradge

Corn. The inferior portions of ore separated from the best ore by cobbing.
Fay

draft

A survey line in a traverse. Syn:leg

draft engine

Corn. An engine used for pumping.

draft gage

An instrument used to measure the small pressure differentials below
atmospheric; e.g., an inclined manometer to measure the pressure
difference between a flue and the atmosphere for combustion control.
ACSG, 2

draft hole

An opening through which air is supplied to a furnace. Fay

draftsman

In petroleum production, one who specializes in drawing subsurface
contours in rock formations from the data obtained by a geophysical
prospecting party. The draftsman plots maps and diagrams from computations
based on recordings of seismograph, gravimeter, magnetometer, and other
petroleum prospecting instruments, and from prospecting and surveying
field notes. DOT

drag

a. The frictional resistance offered to a current of air or water;
resistance created by friction. Fay
b. Fragments of ore torn from a lode by a fault. Such fragments are
scattered along the line of the fault and are usually inclosed within
crushed or brecciated pieces of the rock traversed by that fault.
c. The flexuring of strata associated with faults. In a normal fault, the
coal seam often bends upward on the downthrow side and downward on the
upthrow side. Thus, drag is an indication of direction of displacement of
the beds. Also called terminal curvature. See also:coal lead
Nelson
d. In an inclined stope, the weight of the arch block is resolved into two
components, one at right angles to the dip, which tends to close the
opening, and one parallel to the dip, which tends to produce movement of
the hanging wall with respect to the footwall. This movement is known as
drag, or creep. Syn:creep
e. See also:drag ore
f. An appliance to be attached to the rear of a loaded train of cars to
prevent the cars from running down the incline or grade in case the cable
should break. See also:backstay
g. The uptilted or downtilted curve in rock beds or strata adjacent to a
fault. Long
h. The force exerted by a flowing fluid on an object in or adjacent to the
flow. AGI
i. The bending of strata on either side of a fault, caused by the friction
of the moving blocks along the fault surface; also, the bends or
distortions so formed. CF:bull

drag angle

The angle at which the leading surface of a cutting plane or point meets
the surface to be cut. If less than 90 degrees , the angle is said to be
negative; if over 90 degrees , it is called a positive rake or drag angle.
CF:rake

drag bit

a. A noncoring or full-hole boring bit that scrapes its way through strata
that must not be too hard. It may be a two-, three-, or four-bladed
pattern with various curves and cutaways. The drilling fluid passes down
through the hollow drill stem to the cutting point.
See also:roller bit
b. Various kinds of rigid steel bits provided with fixed (as contrasted to
the movable or rolling cutting points of a roller bit) and sometimes
replaceable cutting points, which are rotated to drill boreholes in soft
to medium-hard rock formations. See also:bit; fishtail bit; mud bit.
Long

drag bolt

A coupling pin. Standard, 2

drag brake

On a revolving shovel, the brake that stops and holds the drag (digging)
drum. Nichols, 2

drag breccia

Fragments of rock in the brecciated zone of a fault. Long

drag bucket

A bucket widely used in sampling sea-floor rock deposits in all depths up
to and exceeding 30,000 ft (9.1 km). See also:drag dredging
Mero

drag cable

In a dragline or hoe, the line that pulls the bucket toward the shovel.
Nichols, 1

drag-chain conveyor

A type of conveyor having one or more endless chains that drag bulk
materials in a trough. See also:chain conveyor; drag conveyor;
portable drag conveyor. Syn:bar flight conveyor

drag classifier

Inclined trough that receives ore pulp, and classifies it into settling
solids and relatively fine pulp overflow. The settled material is
continuously dragged up slope and out by a continuous belt, perhaps
provided with transverse scrapers. Pryor, 3

drag conveyor

A conveyor in which an endless chain, having wide links carrying
projections or wings, is dragged through a trough into which the material
to be conveyed is fed; it is used for loose material.
See also:chain conveyor

drag cut

a. A cut on which groups of holes are drilled at increasing heights above
floor level and at increasing angles from the free face. The shots are
fired to break out successive wedges of strata across the width of the
face. BS, 12
b. A drill-hole pattern widely used in high-speed drilling. The cut holes
are inclined downward to cut a wedge along the floor, the other holes
being drilled to break to the cut holes. Also called horizontal cut.
Nelson
c. A cut in which the cut holes are angled in the vertical plane toward a
parting in order to breakout the ground along the parting. Drag cut rounds
are suitable for small drifts 6 to 7 ft (1.83 to 2.13 m) wide or where
shallow pulls are sufficient, but the drag cut does not find much
application in large-scale drifting practice. See also:bottom cut
McAdam, 2

drag dip

Local change of attitude as a result of drag near a fault.

drag dredging

A method in which the bucket is lowered to the sea floor and dragged over
the ocean floor for some distance in order to collect samples. Dredge and
trawl hauls normally can only give a rough indication of heavy or light
concentrations of the minerals within an area. Mero

drag engineer

See:slope engineer

drag fold

A minor fold, usually one of a series, formed in an incompetent bed lying
between more competent beds, produced by movement of the competent beds in
opposite directions relative to one another. Drag folds may also develop
beneath a thrust sheet. They are usually a centimeter to a few meters in
size. AGI

drag head

The underwater end of a hydraulic dredging system that comes in contact
with bottom sediments and through which a dredge pump recovers a slurry of
water and sediment. Padan

dragline

A type of excavating equipment that casts a rope-hung bucket a
considerable distance; collects the dug material by pulling the bucket
toward itself on the ground with a second rope; elevates the bucket; and
dumps the material on a spoil bank, in a hopper, or on a pile.
See also:boom; excavator.

dragline boom

A crane boom used with a drag bucket. Carson, 1

dragline dredge

An excavation system involving a digging bucket, cable, and boom, which
permits the recovery of sediments and rocks from trenches, canals, and
pits that contain or are covered by water.

dragline engineer

See:slope engineer

dragline excavator

A mechanical excavating appliance consisting of a steel scoop bucket that
is suspended from a movable jib; after biting into the material to be
excavated, it is dragged toward the machine by means of a wire rope.
CTD

dragline scraper

An apparatus for moving soil, gravel, or other loose material. It
ordinarily consists of a scraper attached to an endless cable or belt
operated by a drum or sprocket wheel, and can be drawn back and forth by
the operator at the drum.

drag loader

See:dragman

dragman

One who operates a scraper loading machine, known as a drag, to load ore
into cars or chutes. Also called drag loader; drag operator. DOT

dragon

S. Staff. A barrel in which water is raised from a shallow shaft.

dragonite

A rounded quartz pebble representing a quartz crystal that has lost its
brilliancy and angular form; in gravels, once believed to be a fabulous
stone obtained from the head of a flying dragon.

dog-and-chain

An iron lever with a chain attached by which props are withdrawn.
Fay

dogger

a. A large, irregular nodule, usually of clay ironstone, sometimes
containing fossils, found in a sedimentary rock, as in the Jurassic rocks
of Yorkshire, England. AGI
b. An English term for any large, lumpy mass of sandstone longer than it
is broad, with steep rounded sides. AGI

doghole

A small opening from one place in a coal mine to another; smaller than a
breakthrough. Syn:monkey hole

doghole mine

Name applied to small coal mines that employ fewer than 15 miners. The
so-called dogholes are most numerous in Kentucky, but there are many in
Virginia and West Virginia.

dogholes

See:doghole mine

dog hook

a. A strong hook or wrench for separating iron boring rods. Fay
b. An iron bar with a bent prong used in handling logs. Fay

doghouse

a. The structure enclosing the drill platform and machine. Long
b. A small shelter in which members of a drill crew change clothing.
CF:changehouse
c. See:forechamber
d. Any enclosure or small chamber in a mine used for storage or resting.

dog iron

A short bar of iron with both ends pointed and bent down so as to hold
together two pieces of wood into which the points are driven; or one end
may be bent down and pointed, while the other is formed into an eye, so
that if the point be driven into a log, the other end may be used to haul
on. Zern

dogleg

a. An abrupt angular change in course or direction, as of a borehole or in
a survey traverse. Also, a deflected borehole, survey course, or anything
with an abrupt change in direction resembling the hind leg of a dog.
AGI
b. An abrupt bend or kink in a wire rope or cable. Long
c. An abrupt bend in a path, piping system, or road. Long

dogleg severity

Same as deflection angle; hole curvature. Long

dogs

a. Eng. In the plural; bits of wood at the bottom of an air door.
Fay
b. See also:dog

dog spike

A spike generally used to fasten rails to the sleepers when laying track.
Their length should be 1/2 in (1.27 cm) less than the depth of the sleeper
into which they are being pounded. Sinclair, 5

dog-tooth spar

Calcite with sharp scalenohedral termination.

dogtooth spar

Calcite in acute scalenohedral crystals facing like dogs' teeth into an
open cavity or vein. See also:scalenohedron

doit

Eng. Foulness, or damp air. Fay

dole

A division of a parcel of ore. Also spelled dol. Fay

dolerite

a. In the United States, a syn. of diabase. AGI
b. In British usage, the preferred term for what is called diabase in the
United States. Etymol: Greek doleros, "deceitful," in reference to the
fine-grained character of the rock that makes it difficult to identify
megascopically. CF:diorite; trap. Syn:whin

doleritic

a. Of or pertaining to dolerite. See also:ophitic
b. A preferred syn. of ophitic in European usage. AGI

dolerophanite

A monoclinic mineral, Cu2 (SO4 )O ; brown; reported at Mt.
Vesuvius. Also spelled dolerophane.

dolina

See:doline

doline

A syn. of sinkhole. Also spelled: dolina. Etymol: German transliteration
from Slovene "dolina," "valley." AGI

drain tunnel

A tunnel constructed for disposing of mine water. Long tunnels have been
driven in some mining districts for the purpose of passing under the lower
workings of several mines and tapping the water for the entire group.
Where topographic features permit, a drain tunnel--more properly called an
adit--may also be driven to serve a single mine. The chief advantages of a
drain tunnel lie in saving the cost of pumping and eliminating the danger
of the mine being flooded through failure of the pumps. Also called
drainage tunnel. CF:drainage

dranyam

A new cutter loader devised by Maynard Davies and developed at the Central
Engineering Establishment of the National Coal Board of Great Britain. A
shearer drum is carried on a vertical shaft in contrast to the horizontal
shaft in the Anderson shearer. Nelson

draper washer

Vertical-current separator (obsolete) used to separate shale from coal.
Pryor, 3

draping

Warping in the beds overlying a reef, as a result of differential
compaction.

draft

a. S. Staff. The quantity of coal hoisted in a given time.
b. The pressure required to supply air to a furnace and to remove the flue
gases from the furnaces. Natural draft is produced by a chimney, while
artificial draft is produced by fans and is controlled by the speed of the
fans, by variation in the pitch of the fan blades, or by dampers.
Francis, 2

dravite

A trigonal mineral, 3[NaMg3 Al6 (OH,F)4 (BO3 )
3 Si6 O18 ] ; tourmaline group; forms series with
schorl and with elbaite; in triangular or hexagonal prisms; pyroelectric
and piezoelectric; in metamorphic and metasomatic lime-rich rocks; slices
are used to measure transient blast pressures.

draw

a. The horizontal distance on the surface ahead of an underground coal
face over which the rocks are influenced by subsidence.
See also:angle of draw
b. The break in strata from a coal face to the surface; the angle between
this break and the vertical. Mason
c. To remove broken ore by gravity from stopes, chambers, or ore bins by
aid of chutes or conveyors. Pryor, 3
d. To mine out or rob the pillars in a mine, after the rooms are worked
out.
e. To pull bit-bank metal toward a diamond by peening and calking when
handsetting a diamond bit. Long
f. See:pull
g. The effect of creep upon the pillars of a mine. Fay
h. To raise ore, coal, rock, etc., to the surface; to hoist. Fay
i. To transport by hand; to put; to tram. Mason
j. To allow ore to run from working places and stopes through a chute into
trucks. CTD
k. To withdraw timber props from overhanging coal, so that it falls ready
for collection. CTD

drawability

A measure of the workability of a metal subject to a drawing process. This
term is usually expressed to indicate a metal's ability to be deep-drawn.
ASM, 1

draw a charge

Remove explosives. Zern

draw bead

a. A bead or offset used for controlling metal flow. ASM, 1
b. Riblike projections on draw rings or hold-down surfaces for controlling
metal flow. ASM, 1

drawcut

a. In underground blasting, cut holes that are inclined upward.
Lewis
b. In rock blasting, bottom cut. Pryor, 3
c. See:drag cut

drawer

a. Scot. A man or boy who takes ore or rock from the working face to the
shaft, or terminus of the horse or haulage road. One who pushes trams or
drives a horse underground. Fay
b. Derb. A man who hoists ore or rock by means of a windlass, or
otherwise, from a shaft. Fay
c. Putter; trammer; wagoner; a person who moves tubs either manually or
with a machine. Mason

draw firing

Removal of the load from a furnace for a short time, prior to the
completion of burning, to equalize heating of all areas. Also called draw
burning. Bryant

drawgear

The term includes drawbars, chains, shackles, detaching hooks, etc., used
in haulage, winding, and hoisting. Nelson

draw hole

An aperture in a battery through which the coal or ore is drawn.
Fay

drawing

a. Recovering the timbers, chocks, etc., from the goaves. This work is
commonly performed with the use of the dog and chain. Fay
b. Knocking away the sprags from beneath the coal after holing.
Fay
c. Raising coal through a shaft or slope. Fay
d. In hydraulic mining, throwing the water beyond the dirt to be removed
and causing it to flow toward the giant. CF:goosing
e. Removing or pulling out the crown bars in a tunnel. Stauffer
f. The movement of tubs. Pryor, 3
g. Forming recessed parts by forcing the plastic flow of metal in dies.
ASM, 1
h. Reducing the cross section of wire or tubing by pulling it through a
die. ASM, 1
i. A misnomer for tempering. ASM, 1
j. Continuous forming of sheet, tube or fibrous glass from molten glass.
Van Vlack

drawing an entry

Removing the last of the coal from an entry. Fay

drawing down

Reduction of cross section of steel by forging. Pryor, 3

drawing lift

The lowest lift of a Cornish pump, or that lift in which the water rises
by suction (atmospheric pressure to the point where it is forced upward by
the plunger). Also called drawlift.

drawing small

When a winding rope, from the effects of wear and tear, has become less in
diameter or in thickness from that cause, it is said to be "drawing
small." Fay

drawing timber

The removal of timbers and supports from abandoned or worked out mine
areas. This work is highly specialized and should be attempted only by the
most experienced persons. Generally, timbers are pulled by a timber puller
that permits the operator to be under a safe roof while doing this work.
In some cases, where so much weight is resting on the timber that it
cannot be removed safely, it must be shot out by use of explosives, and
the roof allowed to fall. See also:sylvester
Kentucky

draw kiln

Scot. A limekiln in which the process of calcination is carried on
continuously, the raw limestone and fuel being put in at the top and the
lime withdrawn at the bottom. Fay

drawman

See:grizzly worker

drawn

The condition in which an entry or room is left after all the coal has
been removed. See also:rob

drawn clay

Clay that is shrunk or decreased in volume by burning. Fay

drawn tube

A tube produced by drawing a tube bloom through a die.
Light Metal Age

drawpoint

a. A spot where gravity fed ore from a higher level is loaded into hauling
units. Nichols, 1
b. Heavy chisel cut across the face of a bit blank a short distance from a
diamond to serve as a starting point for calking the metal toward and
around a diamond being handset. Long

draw slate

A soft slate, shale, or rock approx. 2 in (5.08 cm) to 2 ft (0.61 m) in
thickness, above the coal, and which falls with the coal or soon after the
coal is removed. Fay

draw works

In rotary drilling, that part of the equipment functioning as a hoist to
raise or lower drill pipe and in some types, to transmit power to the
rotary table. See also:hoist

dredge

a. Large floating machine used in underwater excavation for developing and
maintaining water depths in canals, rivers, and harbors; raising the level
of lowland areas and improving drainage; constructing dams and dikes;
removing overburden from submerged orebodies prior to openpit mining; or
recovering subaqueous deposits having commercial value.
CF:grab sampler
b. See:dradge
c. Very fine mineral matter held in suspension in water.
d. A type of bag net used for investigating the fauna of the sea bottom.
CTD
e. In dry process enameling: (1) the application of dry, powdered frit to
hot ware by sifting; and (2) the sieve used to apply powdered porcelain
enamel frit to the ware. Also called dredging. ASTM
f. Any of various machines equipped with scooping or suction devices used
in deepening harbors and waterways and in underwater mining.
Webster 2nd

dredge claims

The bed of an unnavigable river is open to location and patent as public
land, when the opposite banks thereof have not passed into private
ownership. Proprietors bordering on such streams, unless restricted by the
terms of their grant from the government, hold to the center of the
stream, notwithstanding the running of meander lines on the banks thereof,
as the true boundary of the land is the thread of the stream.
Ricketts

dredgemaster

In metal mining, a person who supervises and operates a dredge that is
used to mine metal-bearing sands or gravels (gold, tin, or platinum) at
the bottom of lakes, rivers, and streams. Also called dredgeman.
DOT

dredge pump

A heavy-duty-type centrifuged pump with chrome-carbide or manganese steel
liners. In silts or rounded sand grains their life is often a matter of
months, but where sharp-grained sands or large gravel sizes are being
handled, casing and impeller lives may be figured in hours.
Carson, 2

dredger

a. A vessel specially equipped for dredging.
See also:bucket-ladder dredge; dipper dredger; grab dredger;
sand-pump dredger; suction-cutter dredge. CTD
b. Person who dredges. Webster 3rd
c. A dredging machine. Webster 3rd

dredger excavator

An excavator working on the same principle as the bucket-ladder dredger
but designed to work on land. CTD

dredge sump

N. of Eng. A small reservoir at the bottom of a shaft, in which the water
collects and deposits any sediments or debris. See also:settling pit
Fay

dredging

Removing solid matter from the bottom of an area covered by water.

dredging conveyor

A scraper partially immersed in a vessel containing liquid used for
removing any solids that may settle therein. BS, 5

dredging sump

A tank, forming part of the water circuit, in which slurry or small coal
settles and is removed continuously by means of a scraper chain or scraper
buckets. Also called drag tank; sludge sump. BS, 5

dredging tube

The large tube of a dredging machine that operates by suction.
Standard, 2

dredging well

The opening through a dredging vessel in which the bucket ladders work.
See also:bucket-ladder dredge

dreelite

See:barite

dress

a. To resharpen and restore to size the worn teeth on a roller or diamond
bit. See also:face
b. To restore a tool to its original shape and sharpness by forging or
grinding. Crispin
c. To clean ore by breaking off fragments of the gangue from the valuable
mineral. See also:ore dressing
d. To shape dimension stone.

dressing

a. A general term for the processes of milling and concentration of ores.
Syn:ore dressing
b. The shaping of dimension stone.
c. Separating rock from lumps of coal by chipping with a hammer or similar
means.
d. Can. Developing claims to take them out of wildcat class.
Hoffman

dressing a mine

A method of fraud carried out by a representative of the seller, by
systematically mining out all the low-grade or barren spots in the vein,
leaving only the high-grade spots exposed. Hoover

dribble

Material that adheres to the conveying medium and, being carried beyond
the discharge point, drops off along the return run.

dribbling

In underground excavation, fall of small stone and debris from roof,
warning that a heavy fall may be imminent. Pryor, 3

dried alum

See:burnt alum

drier

A device used for removing water from damp material by evaporation,
supplemented usually with forced circulation of air.

drier man

In salt production, one who tends operations of rotary driers through
which crushed salt is run to drive off contained moisture prior to
grinding, examining the salt discharged from the driers to see that
evaporation of moisture is complete. DOT

dries

Seams in the rock, which are usually invisible in the freshly quarried
material, but which may open up in cutting or on exposure to the weather.
See also:dry

drif

See:drift

drift

a. An entry, generally on the slope of a hill, usually driven horizontally
into a coal seam. Syn:surface
b. The deviation of a borehole from its intended direction or target.
CF:walk
c. A general term, used esp. in Great Britain, for all surficial,
unconsolidated rock debris transported from one place and deposited in
another, and distinguished from solid bedrock; e.g., specif. for glacial
deposits. Any surface movement of loose incoherent material by the wind;
accumulated in a mass or piled up in heaps by the action of wind or water.
See also:fill
d. Apparent offset of aerial photographs with respect to the true flight
line, caused by the displacement of the aircraft owing to cross winds, and
by failure to orient the camera to compensate for the angle between the
flight line and the direction of the aircraft's heading. The photograph
edges remain parallel to the intended flight line, but the aircraft itself
drifts farther and farther from that line. AGI
e. A time variation common to nearly all sensitive gravimeters, due to
slow changes occurring in the springs or mountings of the instrumental
systems; this variation is corrected by repeated observations at a base
station and in other ways. AGI
f. A horizontal opening in or near an orebody and parallel to the course
of the vein or the long dimension of the orebody. Beerman
g. A passageway driven in the coal from the surface, usually above
drainage, following the inclination of the bed. Hudson
h. Forest of Dean. A hard shale.
i. To make a drift; to drive. Webster 3rd
j. A horizontal gallery in mining and civil engineering driven from one
underground working place to another and parallel to the strike of the
ore. It is usually of a relatively small cross section. Larger sections
are usually called tunnels. Fraenkel
k. A heading driven obliquely through a coal seam. CTD
l. A heading in a coal mine for exploration or ventilation. CTD
m. An inclined haulage road to the surface. CTD
n. In oil well surveying, the angle from a drill hole to the vertical.
See also:inclination
o. A flat piece of steel of tapering width used to remove taper shank
drills and other tools from their holders. ASM, 1
p. A tapered rod used to force mismated holes in line for riveting or
bolting. Sometimes called a driftpin. ASM, 1
q. A gradual change in a reference that is supposed to remain constant. An
instrument such as a gravimeter may show drift as a result of elastic
aging, long-term creep, hysteresis, or other factors. AGI
r. A general term applied to all rock material (clay, silt, sand, gravel,
boulders) transported by a glacier and deposited directly by or from the
ice, or by running water emanating from a glacier. Drift includes
unstratified material (till) that forms moraines, and stratified deposits
that form outwash plains, eskers, kames, varves, glaciofluvial sediments,
etc. The term is generally applied to Pleistocene glacial deposits in
areas (as large parts of North America and Europe) that no longer contain
glaciers. The term drift was introduced by Murchison in 1839 for material,
then called diluvium, that he regarded as having drifted in marine
currents and accumulated under the sea in comparatively recent times; this
material is now known to be a product of glacial activity.
CF:glacial drift
s. One of the wide, slower movements of surface oceanic circulation under
the influence of, and subject to diversion or reversal by, prevailing
winds; e.g., the easterly drift of the North Pacific.
Syn:drift current
ocean currents and wind stress. The speed of an ocean current or ice floe,
usually given in nautical miles per day or in knots. Sometimes used as a
short form of littoral drift. See:current
t. In South Africa, a ford in a river. The term is used in many parts of
Africa to indicate a ford or a sudden dip in a road over which water may
flow at times. Syn:drif

drift and pillar

N. Staff. A system of working coal similar to the room and pillar system.
Fay

drift angle

The angular deviation of a borehole from vertical and/or its intended
course. See also:deflection angle

drift angle buildup

The rate of the increase in the drift angle that is generally expressed as
the number of degrees increase for a specific drilled footage; e.g., 2
degrees per 100 ft (30.5 m). Long

driftbolt

a. A bolt for driving out other bolts or pins. Webster 3rd
b. A metal rod, for securing timbers, resembling a spike but with or
without point or head. Webster 3rd

drift coal

See:allochthonous coal

drift coalfields

Coalfields formed by forests on higher ground being carried away by floods
into lakes. Mason

drift copper

Native copper transported from its source by a glacier. AGI

drift current

See:drift

drift curve

Graph of a series of gravity values read at the same station at different
times and plotted in terms of instrument reading versus time. AGI

drift driller

In metal mining, one who operates a heavy, mounted, compressed-air,
rock-drilling machine in driving drifts (horizontal passages running
parallel to the vein opened up to facilitate mining of the ore).
DOT

drifted

a. A borehole, the course of which has deviated or departed from the
intended direction or did not reach its intended target. Long
b. Inward-bulged casing that has been straightened by the use of a drift.
See also:drift
c. A horizontal underground passage parallel to or along a vein or related
structure. Long

drift epoch

See:glacial epoch

drifter

a. An air-driven, percussive rock drill; also called leyner; liner.
Long
b. A drill crewman, miner, or laborer who travels from place to place,
only working a short period of time at each place. CF:boomer
Long
c. A person skilled in the use of air-driven, percussive rock drills and
other processes utilized in excavating horizontal underground passages or
tunnels. Long
d. An excavator of mine drifts. Webster 3rd

drifter bar

See:bar; drill column.

drifter drill

The heaviest form of hammer drill made in various sizes depending upon the
severity of the work to be done. The heaviest type weighs more than 200 lb
(91 kg) and is used for holes up to 20 ft (6.1 m) in depth. Must be
mounted on a column or bar. Lewis

drift frame

See:square set

drift indicator

Various types of mechanical or photographic devices used to determine the
compass bearing and inclination of the course of a borehole.
CF:clinometer

driftman

In bituminous coal mining, one who is engaged in driving a drift, a
horizontal passageway underground following the coal vein in a mine.
DOT

driftmeter

An instrument for determining the inclination of a drill pipe from the
vertical and the depth of measurement. AGI

drift mine

a. A placer or gravel deposit worked by underground mining methods.
Webster 3rd
b. A mine that opens into a horizontal or practically level seam of coal.
This type of mine is generally the easiest to open as the mine opening
enters into the coal outcrop. Kentucky
c. One opened by a drift. Pryor, 3

drift mining

a. A term applied to working alluvial deposits by underground methods of
mining. The paystreak, varying from 2 to 8 ft (0.6 to 2.4 m), sometimes
greater, is reached through an adit or a shallow shaft. Wheelbarrows or
small cars may be used for transporting the gravel to a sluice on the
surface. If relatively large, the deposit is removed in a system of
regular cuts or slices taken across the paystreak, working generally in a
retreating fashion from the inner limit of the gravel. Drift mining is
more expensive than sluicing or hydraulicking; consequently it is used
only in rich ground. See also:placer mining
b. The working of relatively shallow coal seams by drifts from the
surface. The drifts are generally inclined and may be driven in rock or in
a seam. Drift mining may be viewed as intermediate between opencast coal
mining and shaft or deep mining. See also:development drift;
surface drift. Nelson

drift peat

A peat deposit associated with or embedded in glacial drift. Fay

drift salt

Fluffy, flaky salt particles due to wind and wave action, which produce a
mist over the surface of solar salt ponds. The mist contains minute
particles of salt, which are driven to the lee shore and deposited as a
scale. Kaufmann

drift set

A strong timber set in a drift that may form the anchorage for the timber
sets of the stope above. Nelson

drift slicing

Side slicing as a method of stoping massive deposit. Alternative to top
slicing. Pryor, 3

drift stope

The excavation of the development drift together with the stope in
overhand stoping. Employed in cases where the hanging wall is strong.
Nelson

drift stoping

See:sublevel stoping

drift theory

That theory of the origin of coal that holds that the plant matter
constituting coal was washed from its original place of growth and
deposited in another locality where coalification then came about.
See also:allochthonous coal

drikold

See:dry ice

drill

a. Any cutting tool or form of apparatus using energy in any one of
several forms to produce a circular hole in rock, metal, wood, or other
material. See also:calyx drill; churn drill; core drill; diamond drill;
rock drill; rotary drill; shot drill. Long
b. To make a circular hole with a drill or cutting tool. Long

drillability

a. The relative speed at which a material may be penetrated by a drill
bit. High drillability denotes easy penetration at a fast rate.
Long
b. The specific value of the drilling properties of a rock expressed in
terms of the drilling rate under certain technical conditions.
Fraenkel

drill ahead

a. To sink a borehole into solid or unconsolidated rock material, such as
overburden or glacial till, to a considerable depth below the bottom of
the casing or drivepipe. Long
b. To restart or resume drilling operation. Long
c. To drill boreholes in advance of mine workings to explore for or locate
old mine workings or a water-bearing formation. Long

drill bar

A drill column that is set horizontally instead of vertically in an
underground workplace. See also:bar; drill column. Long

drill base

Metal or wood framework on which a drilling machine is mounted.
Long

drill bit

a. One of a number of different types of detachable cutting tools used to
cut circular holes in rock, wood, metal, etc. Also called drill crown in
Africa and England. Long
b. Any device at the lower end of a drill stem, used as a cutting or
boring tool in drilling a hole; the cutting edge of a drill.
CF:core bit

drill boom

An adjustable arm projecting from a drill carriage to carry a drill and
hold it in position. BS, 12

drill bort

See:drill diamond

drill by

See:bypass

drill cable

In a strict sense, the term should only be used to designate the heavy
rope or cable used as the connecting link between the drill stem and the
walking beam on a churn drill. However, the term now is commonly used to
signify any cable or wire rope used in hoisting drill rods, casing, and
other borehole-drilling equipment used with a drill machine, such as a
calyx drill, diamond drill, etc. Also called drilling line; drill line.
Long

drill capacity

The lineal feet of drill rod of a specified size that a hoist on a diamond
or rotary drill can lift or that the associated brake is capable of
holding on a single line; also sometimes used to designate the size of a
drill machine, based on the depth to which it is capable of drilling.
See also:lifting capacity

drill carriage

A movable platform, stage, or frame that incorporates several rock drills
and usually travels on the tunnel track; used for heavy drilling work in
large tunnels. See also:drill frame

drill collar

A length of extra heavy wall drill rod or pipe connected to a drill string
directly above the core barrel or bit, the weight of which is used to
impose the major part of the load required to make the bit cut properly. A
drill collar is usually of nearly the same outside diameter as the bit or
core barrel on which it is used. Not to be confused with guide rod.
Long

drill column

A length of steel pipe equipped with a flat cap at one end and a jackscrew
on the opposite end by means of which the pipe can be wedged securely in a
vertical or horizontal position across an underground opening to serve as
a base on which to mount a small diamond or rock drill. Syn:drifter bar;
drill bar; drill stem. See also:bar

drill core

A solid, cylindrical sample of rock produced by an annular drill bit,
generally rotatively driven but sometimes cut by percussive methods.
Syn:core

drill cradle

The metal channel on which a heavy drill is fed forward as drilling
proceeds. BS, 12

drill cuttings

See:well cuttings; cuttings; sludge.

drill diamond

Industrial diamond used in diamond-drill bits and reaming shells for
coring, cutting, or reaming rock. Drill diamonds usually contain obvious
imperfections and inclusions, although the finer grades approach
toolstones in quality. Also called drill bort; drilling bort; drilling
diamond; drilling. CF:toolstone

driller

a. A person who has acquired enough knowledge and skill to operate and
assume the responsibility of operating a drill machine. Also called drill
runner; runner; tool pusher. Syn:drillman
Long
b. The person in charge of the rig and crew during one tour and who
handles the drilling controls. Brantly, 2
c. A drilling machine. Standard, 2
d. Can. Property being diamond drilled as compared to one undergoing
underground development. Hoffman
e. N. of Eng. Uses an electric or pneumatic twist drill to make shotholes
in the coal. Shotholes in the gateway caunches are usually put on by the
stoneman. Trist

driller's log

A description of the borehole based on the daily logs from the driller.

drill extractor

Tool for retrieving broken piece of drill from borehole. Pryor, 3

drill feed

The mechanism for advancing the drill bit during boring. Nelson

drill fittings

Devices, parts, and pieces of equipment used downhole in drilling a
borehole. Also called downhole equipment. Long

drill frame

A drill mounting often made at the mine to suit the tunnel requirements.
It usually comprises two girders strapped together to form a replica of
the tunnel shape but smaller in size. The structure is mounted on wheels
and provision is made for clamping the drills to various parts of the
frame according to the drill-hole pattern in use. It contains a central
opening to allow the passage of the loading machine, cars, or conveyor.
Nelson

drill gage

The width across the cutting bit or diameter of the drilled hole. With
tungsten-carbide bits it is possible to drill long holes without the loss
of gage. Nelson

drill hole

a. A hole in rock or coal made with an auger or a drill.
b. Technically, a circular hole drilled by forces applied percussively;
loosely and commonly, the name applies to a circular hole drilled in any
manner. Long
c. Used by diamond drillers as a syn. for borehole. CF:borehole
Long

drill-hole counting

When the results of a survey indicate a possible ore deposit, test holes
may be drilled and a special adaptation of a scintillation counter, called
a drill-hole counter, may be lowered in a hole in an attempt to locate,
outline, and assay an orebody. The drill-hole counter can distinguish
between formations by their radiation intensity. Dobrin

drill-hole pattern

The number, position, depth, and angle of the shot holes forming the
complete round in the face of a tunnel or sinking pit. A good drill-hole
pattern will ensure the maximum possible pull and the fragmentation for
easy loading without excessive scatter of material. See also:cut holes
Nelson

drill-hole record

A description of the borehole based on the daily logs from the driller and
the samples and the report of the geologist. Nelson

drill-hole returns

The circulation fluid and entrained cuttings overflowing the collar when
drilling a borehole. Long

drill-hole survey

See:borehole survey

drilling

a. The act or process of making a circular hole with a drill.
See also:drill
b. The operation of tunneling or stoping, whether with a compressed-air
rock drill, a jackhammer, or a drifter. CTD
c. Use of a compressed-air rock drill to prepare rock for blasting.
Pryor, 3
d. The operation of making deep holes with a drill for prospecting,
exploration, or valuation. Pryor, 3

drilling bit

The cutting device at the lower end of cable drilling tools or rotary
drill pipe, the function of which is to accomplish the actual boring or
cutting. AGI

drilling cable

See:cable

drilling column

The column of drill rods to the end of which the bit is attached.
BS, 9

drilling conditioning period

Time spent in circulating a higher-than-normal volume of fluid through the
drilling string while slowly rotating and lowering the string from the
last few feet above to the bottom of a borehole to wash away any
obstructing material before resuming coring operations. Long

drilling jig

a. A device very accurately made of cast or wrought iron that becomes a
guide for the drilling of holes. The work is fastened in the jig, and the
drill is guided through holes drilled in the face of the jig itself. The
use of a jig makes interchangeable work easily obtainable. Crispin
b. A portable drilling machine worked by hand. Fay

drilling life

See:bit life

drilling machine

A hand-operated, or power-driven machine for boring shot holes or
boreholes, in coal, ore, mineral, or rock. See also:drifter drill;
percussive drill; rotary drill; rotary-percussive drill. Nelson

drilling mud

A suspension, generally aqueous, used in rotary drilling and pumped down
through the drill pipe to seal off porous zones and to counterbalance the
pressure of oil and gas; consists of various substances in a finely
divided state among which bentonite and barite are most common. Oil may be
used as a base of water. CF:circulation fluid; mud-laden fluid.
AGI

drilling pattern

The relation of drilled holes to each other and any free faces as part of
the blast design.

drilling platform

Auxiliary equipment for drilling at heights above head level. The drilling
platform is generally assembled and dismantled for each series of drilling
operations. Fraenkel

drilling pressure

See:bit load

drilling rate

a. The depth of penetration achieved per unit of time with a given type of
rock drill, bit diameter, air pressure, etc. See also:penetration rate
Fraenkel
b. The overall rate of advancement of the borehole. BS, 9

drilling rig

A general term for the derrick, power supply, draw works, and other
surface equipment necessary in rotary or cable-tool drilling.
See also:rig

drillings

a. See:drill diamond
b. Incorrectly used as a syn. for cuttings. Long
c. Sometimes designates drill diamonds ranging from 4 to 23 stones per
carat in size. Long

drilling thrust

See:bit thrust

drilling time

a. In rotary drilling, the time required for the bit to penetrate a
specified thickness (usually 1 ft or 0.3 m) of rock. The rate is dependent
on many factors. AGI
b. The elapsed time, excluding periods when not actually drilling,
required to drill a well. AGI

drilling up

Preliminary digging out the clay in the taphole of a furnace. This is done
usually by hand, air, or electric drill. Fay

drilling weight

Also called drilled weight. See:bit load

drill log

The record of the events and the type and characteristics of the
formations penetrated in drilling a corehole. Syn:boring log
CF:log

drillman

See:driller

drill mounting

An appliance to provide a feed pressure and a support for the drilling
machine usually in tunnels. Four main types of drill mountings are in use,
namely, the post, the air leg, the drill frame, and the drill carriage.
Nelson

drill output

The volume of rock (in tons) corresponding to the footage drilled per
hour. Streefkerk

drill pattern

The placement of a number of boreholes in accordance to a predetermined
geometric arrangement. Long

drill pressure

Also called drilling pressure. See:bit load

drill rate

a. The number of feet of borehole drilled in a specified interval of time;
e.g., drilling rate was 80 ft/d (24.4 m/d). Long
b. Price, expressed in dollars, per foot of borehole completed in
accordance with terms specified in a drill contract. Syn:feed rate
Long

drill rig

A drill machine complete with all tools and accessory equipment needed to
drill boreholes.

drill-rod bit

A noncoring bit designed to be coupled to a reaming shell threaded to
couple directly on a drill rod instead of a core barrel. Long

drill runner

a. The tunnel miner who normally handles the rock drills for blasting
purposes. Nelson
b. See:driller

drill sampling

a. A method of sampling a deposit by means of a drill or borehole. The
boreholes may be spaced at the corners of squares or triangles at
distances according to the nature and extent of the deposit.
See also:exploratory drilling
b. The sampling of gravel deposits or extensive low-grade ore deposits by
use of drills. Hoover

drill sharpening machines

Machines for sharpening detachable bits and for making shanks.
Lewis

drill sludge

See:cuttings

drill speed

May be used by drillers as a syn. for drill bit revolutions per minute;
drill rate; feed rate; feed ratio; feed speed; rate of penetration.
Long

drill-split longwalling

The act of mining tabular ores 2 to 5 m thick using a drill-split tool.
Lombardi

drill-split narrow-vein mining

The act of mining narrow veins down to 0.6 m using a drill-split tool on a
carriage that is independently mobile and remote-controlled.
Lombardi

drill-split tool

A device that combines a drill and a splitter, which is a unique tool
designed to apply radial and axial loads to a rock mass, into a single
tool that drills and splits rock in recurring cycles. Lombardi

drill steel

a. A round or hexagonal steel rod for boring in coal, ore, or rock. It
consists of shank, shaft, and bit. It forms an important part of
jackhammers and drifters. Nelson
b. Hollow steel connecting a percussion drill with the bit.
Nichols, 1
c. See:stem

drill-steel set

A series of integral drill-steel sizes consisting of starter and follower
bits, necessary for drilling a hole to a certain depth. The length
increment is usually determined by the wear of the bit and the feed length
of the feeding device. Fraenkel

drill stem

a. In standard drilling, a cylindrical bar of steel or iron screwed onto
the cable tool bit to give it weight. AGI
b. In rotary drilling, a string of steel pipe screwed together and
extending from the rig floor to the drill collar and bit at the bottom of
the hole. The drill pipe transmits the rotating motion from the rotary
table to the bit and conducts the drilling mud from the surface to the
bottom of the hole. See also:drill string

drill-stem test

A procedure for determining the potential productivity of an oil or gas
reservoir by measuring reservoir pressures and flow capacities while the
drill pipe is still in the hole, the well is still full of drilling mud,
and usually the well is uncased. The tool consists of a packer to isolate
the section to be tested and a chamber to collect a sample of fluid. If
the formation pressure is sufficient, fluid flows into the tester. Abbrev:
DST. AGI

drill string

The assemblage of drill rods, core barrel and bit or drill rods, drill
collars, and bit in a borehole, which is connected to and rotated by the
drill machine on the surface at the collar of the borehole. Also called
drill stem. See also:string

drill thrust

See:bit load

drip feeder

a. Oil reservoir set to discharge lubricant at steady rate in drops per
minute. Pryor, 3
b. Reagent feeder sometimes used in flotation process to meter chemicals
into pulp. Pryor, 3

dripping fault

A fault down which small quantities of water seep into mine workings. A
dripping fault is a hazard, as mining operations may loosen or open it and
cause an inrush of water. Nelson

dripstone

A general term for any cave deposit of calcite or other mineral formed by
dripping water, including stalactites and stalagmites.
See also:cave onyx; dropstone.

drivage

A general term for a roadway, heading, or tunnel in course of
construction. It may be horizontal or inclined but not vertical.
Nelson

drive

a. To excavate horizontally, or at an inclination, as in a drift, adit, or
entry. Distinguished from sinking and raising.
b. A tunnel or level in or parallel to and near a mineralized lode or
vein, as distinct from a crosscut, which only gives access normal to the
lode. Pryor, 3
c. An underground passage for exploration, development, or working of an
orebody. Nelson
d. To advance or sink drive pipe or casing through overburden or broken
rock formation by chopping, washing, or hammering with a drive hammer or
by a combination of all three procedures. Long

drive collar

See:pipe drivehead

drivehead

a. The driving mechanism for a conveyor. The expressions head-end drive,
intermediate drive, and tail-end drive, indicate the position of the
drivehead or heads. Nelson
b. A heavy iron cap or angular coupling fitted to top of pipe or casing to
receive and protect the casing from the blow delivered by a drive block
when casing or pipe is driven through overburden or other material. Also
called drive cap; driving cap. Syn:pipe drivehead; drive collar.
Long
c. The swivel head of a diamond- or rotary-drill machine. Long

drivepipe

a. A thick-walled outside-coupled pipe, fitted at its lower end with a
sharp steel shoe. It may be driven through overburden or other material by
repeated pile-driverlike blows delivered to the upper end of the pipe by a
heavy drive block. Long
b. Casing pipe driven into deep drill hole to hold back water or prevent
caving. In shallow drilling of alluvials, bottom pipe of string that may
be battered down. Drivehead and drive shoe are also used in this work.
Pryor, 3
c. Pipe driven short distance into dumps or unconsolidated ground to
obtain samples. See also:conduit

drivepipe ring

a. A heavy sleevelike device attached to a drill floor to steady and guide
the pipe or casing being driven. Long
b. A device for holding the drivepipe while being pulled from well.
Fay

drive sample

A dry sample of soft rock material, such as clay, soil, sand, etc.,
obtained by forcing, without rotation, a short, tubular device into the
formation being sampled by hydraulic pressure or the piledriver action of
a drive hammer. Long

drive sampler

A short tubelike device designed to be forced, without rotation, into soft
rock or rock material, such as clay, sand, or gravel, by hydraulic
pressure or the piledriver action of a drive hammer to procure samples of
material in as nearly an undisturbed state as possible.
CF:piston sampler

drive sampling

The act or process of obtaining dry samples of soft rock material by
forcing, without rotation, a tubular device into the material being
sampled by pressure generated hydraulically, mechanically, or by the
piledriver action of a drive hammer. Long

drive shaft

a. Main driving shaft on which the drive and conveyor sprocket wheels or
pulleys are mounted. This shaft is connected to the drive unit through a
coupling, sprocket wheel, gear, or other form of mechanical power
transmission.
b. A shaft used to support the end of a conveyor screw in a trough end and
as a driving connection between a conveyor screw and the power
transmitting medium.

drive unit

The mechanism that imparts the reciprocating motion to a shaker conveyor
trough line. The term is frequently shortened to drive, such as shaker
drive, uphill drive, etc. Jones, 1

drive wedge

A metal wedge, driven into a wooden or soft-metal base plug in a borehole,
that acts as a fixed point on which and by means of which a deflection
wedge may be set and oriented. Long

driving

a. Extending excavations horizontally or near the horizontal plane.
CF:sinking; raising. Nelson
b. The making of a tunnel or level (a drive) in a mineralized lode or
vein, as distinct from making one in country rock (crosscutting).
CTD
c. Breaking down coal with wedges and hammers. CTD
d. A long narrow underground excavation or heading. Fay
e. Eng. In the Bristol coalfield, a heading driven through rock.
Fay

driving cap

Steel cap placed above line of casing pipes of drill hole to protect
threaded top of pipe while driving them deeper. Driving shoe gives
protection to the bottom pipe of line. Pryor, 3

driving head

The driving mechanism of a belt conveyor. It consists of an electric motor
or compressed-air turbine connected through a train of reduction gearing
to the drum or drums. Motion is imparted to the belt by the frictional
grip between it and the drums. Sinclair, 5

driving on line

The keeping of a heading or breast accurately on a given course by means
of a compass or transit. Also, called driving on sights.

drop

a. Granulated material obtained by pouring melted material into water.
Standard, 2
b. In the roof of a coal seam, a funnel-shaped downward intrusion of
sedimentary rock, usually sandstone. See also:stone intrusion
AGI
c. The vertical displacement in a downthrow fault; the amount by which the
seam is lower on the other side of the fault. CTD
d. In an air lift, the distance the water level sinks below the static
head during pumping. Lewis
e. The small downward descent of the upper section of a drill rod, casing,
or pipe into a lower like section when the threads of the box- and
pin-threaded parts match, so that upper and lower sections may be screwed
together without cross-threading. Long
f. The sudden descent of a bit that occurs when a bit encounters a cavity
or cuts through a hard rock and enters a very soft rock. Long
g. To lower drill-string equipment into a borehole. Long
h. To lower the cage to receive or discharge the car when a cage of more
than one deck is used. Fay
i. To allow the upper lift of a seam of coal to fall or drop down.
Fay
j. To lose equipment in a borehole. Long

drop ball

A method of breaking oversize stones left after quarry blasting. The balls
weigh from 30 hundredweight (1,360 kg) to 2 st (1.8 t) (many use old cones
from gyratory breakers) and are dropped from a crane on to the oversize
stone. The drop height varies from about 20 to 33 ft (6.1 to 10.1 m). The
method is economical and avoids secondary blasting. Nelson

drop-bottom cage

A cage so designed that the middle section of the floor drops a few inches
when the cage is lifted from the keps. The mine car is thus kept
stationary and secure. Nelson

drop-bottom car

A mine car so constructed that all the haulage motor has to do is to pull
the loaded trip across the dump. A trigger trips the flaps in the bottom
of the car, allowing the coal to drop out, and a second one closes the
flaps as the car leaves the dump. See also:mine car

drop box

Placed at intervals along tailings line to compensate for slope in excess
of that required to keep the pulp moving gently through its launders or
pipes. Pryor, 1

drop cut

The initial cut made in the floor of an open pit or quarry for the purpose
of developing a bench at a level below the floor.

drop doors

Hinged doors at the bottom of a cupola furnace, which drop down to allow
the furnace to be cleaned. Mersereau, 2

drophammer

a. A forging hammer that depends on gravity for its force. ASM, 1
b. A pile driving hammer that is lifted by a cable and obtains striking
power by falling freely. Nichols, 1

drop log

A timber that in an emergency can be dropped by a remote control across a
mine track at the top or bottom of an incline to derail cars.

drop on

Portable rail crossing used to transfer wagons from one track to another.
Hammond

dropped core

Pieces of core not picked up or those pieces that slip out of the core
barrel as the barrel is withdrawn from the borehole. Long

dropper

a. A branch vein pointing downwards. See also:leader
b. A spar dropping into the lode. Zern
c. See:feeder
d. A branch leaving a vein on the footwall side. Zern
e. See:car runner; car dropper.

dropping pillars and top coal

Aust. The second working, consisting of drawing the pillars, and in thick
seams breaking down the upper portion of the seam that was left
temporarily in position. Fay

dropping stones

See:stalagmite

drop pit

A shaft in a mine, in which coal is lowered by a brake wheel.

drops

Drops of 12 in (30.5 cm) or more in a line of sluices that are formed by
allowing the discharge end of one box to rest on the head of the
succeeding sluice, instead of telescoping into it. This method ensures a
drop of 12 in or more (depending on the depth of the sluice box) at the
end of each sluice, which usually is sufficient to disintegrate fairly
stiff clay. Griffith

drop shaft

A monkey shaft down which earth and other matter are lowered by means of a
drop (that is, a kind of pulley with brake attached); the empty bucket is
brought up as the full one is lowered. See also:cofferdam

drop-shaft method

This sinking system consists in the use of a cutting shoe on the bottom of
a shaft lining that is being continually augmented as the shoe descends,
the material inside the lining being excavated. Sinclair, 2

drop sheet

N. of Eng. A door, made of canvas, by which the ventilating current is
regulated and directed through the workings. See also:curtain
Fay

drop staple

Eng. An interior shaft, connecting an upper and lower seam, through which
coal is raised or lowered. Fay

dropstone

a. An oversized clast in laminated sediment that depresses the underlying
laminae and may be covered by "draped" laminae. Most dropstones originate
through "ice-rafting"; other sources are floating tree roots and kelp
holdfasts.
b. A stalagmatitic variety of calcite. CF:dripstone

drop sulfur

Granulated material obtained by pouring the melted material into water.
Standard, 2

drop warwicks

Steel joists hinged to a substantial cross joist in the roof that are held
up by a stirrup during normal running. If a tram runs away down the
incline, the stirrup is disengaged by means of a wire operated from the
top of the incline; one end of the hinged joist falls into the rail track
and arrests the runaway. Mason

drop ways

Openings connecting parallel passages that lie at different levels.
AGI

drop weights

A method of breaking oversize stones after primary blasting at a quarry.
See also:drop ball

dross

a. The scum that forms on the surface of molten metals largely because of
oxidation, but sometimes because of the rising of impurities to the
surface, and which contains metal and metal oxides. ASM, 1
b. Small coal that is inferior or worthless and often mixed with dirt.
Nelson
c. Refuse or impurity formed in melted metal. A zinc-iron alloy forming in
a bath of molten zinc while galvanizing iron. Standard, 2

dross bing

Pile of refuse from a washer. Zern

drowned

Flooded; said of mines underwater.

drowned level

a. A level that is underwater. See also:blind level
b. Part of a drainage drift that, being below both discharge and entry
levels, is constantly full of water. Also called inverted siphon.
BS, 10

drowned waste

Old workings full of water.

Drucker-Prager criterion

A soil and rock failure criterion, which accounts for the general effect
of all three principle stresses by using the invariant of the stress
tensor. Use is limited to numerical formulations, such as finite element
analysis. Desai

druid stone

One of the large sandstone blocks formerly scattered on the English chalk
downs and used in Stonehenge and other Druid temples and circles.
Syn:sarsen stone

drum

a. The large cylinder or cone on which the rope is coiled when hoisting a
load up a shaft. CTD
b. A metal cask, for shipment of material, having a liquid capacity of 55
gal (208 L). See also:barrel
c. In a conical mill, the cylindrical central section. Pryor, 3
d. A general term for a roller around which a belt conveyor is lapped. It
may be a driving, jib, loop, tension, or holding-down drum. Nelson
e. The spoollike part of a hoisting mechanism on which the cable or wire
line is wound. Long
f. A cylindrical or polygonal rim type of wheel around which cable, chain,
belt, or other linkage may be wrapped. A drum may be driven or driving.
The face may be smooth, grooved, fluted, or flanged.

drum counterweight rope

Balance rope direct from drum drive. Hammond

drum curb

See:curb

drum feeder

See:roll feeder

drum filter

Cylindrical drum, which rotates slowly through trough-shaped bath, fed
continuously with thickened ore pulp.

drum horn

Wrought-iron arms or spokes projecting beyond the surface or periphery of
a flat-rope drum, between which the ropes coil or lap. See also:spider
Fay

drumman

See:slope engineer

drumming

The process of sounding the roof of a mine to discover whether rock is
loose. Fay

drummy

a. Loose coal or rock that produces a hollow, loose, open, weak, or
dangerous sound when tapped with any hard substance to test condition of
strata; said esp. of a mine roof. Fay; BCI
b. The sound elicited when bad (loose) roof is tested by striking with a
bar. Hudson

drum pulley

A pulley wheel used in place of a drum. See also:Koepe system
Fay

drum rings

Cast-iron wheels, with projections, to which are bolted the staves or
laggings forming the surface for the hoisting cable to wind upon. The
outside rings are flanged, to prevent the cable from slipping off the
drum. Fay

drum runner

See:incline man

drum separator

A slowly rotating cylindrical vessel that separates run-of-mine coal into
clean coal, middlings, and refuse. It consists of different and adjustable
specific gravities. The low gravity medium in one compartment separates a
primary float product (clean coal), the sink material being lifted and
sluiced into the second compartment where middlings and true sinks (stone)
are separated. Nelson

drum shaft

See:caisson sinking

druse

a. An irregular cavity or opening in a vein or rock, having its interior
surface or walls lined (encrusted) with small projecting crystals usually
of the same minerals as those of the enclosing rock, and sometimes filled
with water; e.g., a small solution cavity, a steam hole in lava, or a
lithophysa in volcanic glass. CF:geode; miarolitic cavity; vug.
AGI
b. A mineral surface covered with small projecting crystals; specif. the
crust or coating of crystals lining a druse in a rock, such as sparry
calcite filling pore spaces in a limestone. Etymol: German. Adj: drusy.
AGI

drusy

a. Pertaining to a druse, or containing many druses. CF:miarolitic
AGI
b. Pertaining to an insoluble residue or encrustation, esp. of quartz
crystals; e.g., a drusy oolith covered with subhedral quartz. AGI

dry

a. Miner's changehouse, usually equipped with baths, lockup cubicles, and
means of drying wet clothing. Pryor, 3
b. A borehole in which no water is encountered or a borehole drilled
without the use of water or other liquid as a circulation medium. Also
called dry hole; duster. Long
c. A borehole that did not encounter a mineral-, oil-, or gas-producing
formation. Also called blank hole; dry hole; duster. Long

dry air

Air with no water vapor. Strock, 2

dry ash-free basis

An analysis expressed on the basis of a coal sample from which the total
moisture and the ash have in theory been removed. BS, 4

dry assay

Any type of assay procedure that does not involve liquid as a means of
separation. CF:wet assay

dry block

The intentional act or process of running a core bit without circulating a
drill fluid until the cuttings at and inside the bit wedge the core
solidly inside the bit. Also called dry blocking. Long

dry blower

See:dry washer

dry blowing

A process sometimes used where water is scarce. The separation of free
gold from the accompanying finely divided material is effected by the use
of air currents. See also:dry cleaning

dry bone

See:dry-bone ore

dry-bone ore

a. An earthy, friable, honeycombed variety of smithsonite in veins or beds in stratified calcareous rocks accompanying sulfides of zinc, iron, and
lead.
b. A variety of hemimorphite. Syn:dry bone

dry bulb temperature

Temperature indicated by a conventional dry thermometer; a measure of the
sensible heat content of air. Hartman, 2

drycleaned coal

Coal from which impurities have been removed mechanically without the use
of liquid media. BS, 4

dry cleaning

The cleaning of coal or ore by air currents as opposed to wet cleaning by
water currents. Appliances for the dry cleaning of coal were first
introduced about 1850 and since that date a variety of methods have been
developed. See also:Kirkup table

drycleaning table

An apparatus in which drycleaning is achieved by the application of air
currents and agitation to a layer of feed of controlled depth on the table
surface. See also:Kirkup table

dry copper

Underpoled copper from which oxygen has been insufficiently removed when
refining, so that it is undesirably brittle when worked cold or hot.
Pryor, 3

dry cyaniding

See:carbonitriding

dry delta

See:alluvial cone; alluvial fan.

dry density

The weight of a unit volume of a dry sample of soil, after the latter has
been heated at a temperature of 103 degrees C. Hammond

dry density/moisture ratio

The relationship between the density of a sample of soil in a dry state
and its moisture content for a given degree of compaction. Such
relationship can be determined from a curve that will reveal the optimum
moisture content. Hammond

dry diggings

a. Placers not subject to overflow.
b. Placer mines or other mining districts where water is not available.
Standard, 2

dry distillation

See:destructive distillation; pyrolysis.

dry drilling

Drilling operations in which the cuttings are lifted away from the bit and
transported out of a borehole by a strong current of air or gas instead of
a fluid. CF:dry running

dry ductor

Compressed-air drill that traps and removes drilling dust instead of
sludging it with added water. Pryor, 3

dryer

An apparatus for drying coal. Dryers are of various types, such as
revolving kilns, flash, and fluidized bed. See also:coal dryer;
dehydrator.

dry fatigue

A condition often appearing in wire rope and often caused by shock loads
in winding. These shock loads are produced by picking up the cage from the
pit bottom with slack chains or by lifting heavy pithead gates or covers.
Sinclair, 5

dry galvanizing

A process in which steel is fluxed in hot ammonium chloride and
subsequently dried by hot air before being passed through a bath of molten
zinc. Hammond

dry grinding

Any process of reducing particle size without the liquid medium.
See also:grinding

dry hole

A drill hole in which no water is used for drilling, as a hole driven
upward. See also:blank hole

dryhouse

See:changehouse

dry ice

Solid carbon dioxide.

dry ice test

A test for detecting glass imitations; if a crystalline substance such as
a gem mineral is placed on a piece of dry ice (solid CO2 ), a
squeaking noise can be heard. This is not true of noncrystalline
substances such as glass or plastic.

dry joint

Positive separation at the plane of contact between adjacent structural
components to allow relative movement arising from differences in
temperature or shrinkage. Hammond

dry kata cooling power

A measure of the rate of heat loss from the bulb of the kata thermometer.
Although the cooling power as obtained by this instrument is not a measure
of the capacity of an atmosphere to cool the human body, nevertheless, it
is useful for comparing different atmospheres and provides a convenient
index of the comfort condition of a working place in a mine. Experience
indicates that a face will be reasonably comfortable for working if the
dry kata cooling power is above 7 on the kata thermometer and the air
velocity above 1 m/s. See also:dehumidification; effective temperature.
Nelson

dry lake

See:playa

dry milling

The comminution of materials in a suitable mill without the presence of a
liquid, either by rods, balls, or pebbles, or autogenously, by the
material itself; used if the subsequent process is a dry process.

dry mineral matter free basis

An analysis expressed on the basis of a coal sample from which the total
moisture and the mineral matter have in theory been removed. BS, 4

dry mining

a. In dry mining every effort is made to prevent the ventilating air
picking up moisture, and throughout the ventilation circuit there is a
wide gap between wet- and dry-bulb temperatures. Dry-bulb temperatures are
therefore comparatively high. Spalding
b. Refers to the reasonably dry footing required for the equipment. Dry
stripping and placer mining with standard earthmoving heavy equipment
depends on good footing for the equipment and short hauls to keep costs in
line. Syn:dry diggings

dry ore

Said of lead or copper ore that contains precious metals (gold and silver)
but insufficient lead or copper to be smelted without the addition of
richer ore. See also:natural ore

dry placer

Gold-bearing alluvial deposit found in arid regions. In some deposits the
gold is in the cementing material that binds the gravel together. Because
of the lack of water, various machines have been devised for the dry
washing of these deposits; such machines commonly include some form of
pulverizer and jigs or tables that use compressed air instead of water in
their operation. Also called desert placer. Lewis

dry process

a. A method of treating ores by heat as in smelting; used in opposition to
wet process, where the ore is brought into solution before extraction of
the metal. See also:wet process
b. The process of making Portland cement in which the raw materials are
ground and burned dry. Mersereau, 2
c. Process whereby dry powdered enameling materials are applied to a
preheated surface. Van Vlack
d. The method of preparation of a ceramic body wherein the constituents
are blended dry, following which liquid may be added as required for
subsequent processing. ASTM

dry puddling

A process of decarbonization on a siliceous hearth in which the conversion
is effected rather by the flame than by the reaction of solid or fused
materials. As the amount of carbon diminishes, the mass becomes fusible
and begins to coagulate (come to nature), after which it is worked
together into lumps (puddle balls, loups) and removed from the furnace to
be hammered (shingled) or squeezed in the squeezer, which presses out the
cinder, etc., and compacts the mass at welding heat, preparatory to
rolling. Silicon and phosphorus are also largely removed by puddling,
passing into the cinder. See also:puddling

dry rotary drilling

See:dry drilling

dry running

To unknowingly or knowingly drill with a bit when the flow of the coolant
and cuttings-removal fluid past the bit has been inadvertently or
deliberately cut off. CF:dry drilling

dry sample

A sample obtained by drilling procedures in which water or other fluid is
not circulated through the drill string and sampling device; hence the in
situ characteristics of the sample have not been altered by being mixed
with water or other fluid. CF:drive sample

dry sampler

Various auger and/or tubular devices designed to obtain unwetted samples
of soft rock material, such as clay, sand, soil, etc., by drilling
procedures wherein water or other fluid is not circulated during the
operation. Long

dry sand

a. A stratum of dry sand or sandstone encountered in well drilling. A
nonproductive sandstone in oilfields. Fay
b. Green sand dried in an oven to remove moisture and strengthen it (a
dried-sand mold is a mold of green sand that is treated as above).
Freeman

dry screening

The screening of solid materials of different sizes without the aid of
water. BS, 5

dry separation

a. The elimination of the small pieces of shale, pyrite, etc., from coal
by a blast of air directed upon the screened coal.
See also:wind method
b. See:dedusting

dry sweating

A process by which impure blister copper is exposed to long oxidizing
heating below fusion point. Standard, 2

dry unit weight

The weight of soil solids per unit of total volume of soil mass. Also
called unit dry weight. See also:unit weight

dry wall stone

Thin-bedded limestone or sandstone suitable only for mortarless (dry)
fencing or retaining walls.

dry wash

A wash that carries water only at infrequent intervals and for short
periods, as after a heavy rainfall. CF:arroyo

dry washer

a. A machine for extracting gold from dry gravel. It consists of a frame
in which there is a rectangular bellows made of canvas; the upper part of
the bellows is made by a plane set at an angle of about 20 degrees ,
across which are riffles. On the top of the machine is a screen on which
gravel is shoveled. The screened gravel falls to a riffled plane from
which it feeds to the riffles on the bellows. The screen and upper riffles
are shaken by an eccentric worked with a crank, and the same crank
actuates the bellows, which blow the dust from the gravel passing over the
riffles. The gold is caught behind the riffles. Only gravel in which no
moisture can be seen can be worked successfully by a dry washer.
Hess
b. A person who operates a dry washer. Syn:dry blower

dry well

A deep hole, covered and usually lined or filled with rocks, that holds
drainage water until it soaks into the ground. Nichols, 1

dual-drive conveyor

A conveyor having a belt drive mechanism in which the conveyor belt is in
contact with two drive pulleys, each of which is driven by a separate
motor. NEMA, 2

dual haulage

In strip mining, the use of two types of haulage at the same mine for
transporting coal from the face to the preparation plant. Usually, coal is
transported from the loading shovel to a transfer station by motorized
units, and rail haulage is used to haul the coal from this point to the
preparation plant. Toenges

dualin

A variety of dynamite consisting of four to five parts nitroglycerin,
three parts sawdust, and two parts potassium nitrate. Webster 2nd

dubiocrystalline

See:cryptocrystalline

duchess

Slate size of 24 in by 12 in (61.0 cm by 30.5 cm). Pryor, 3

duck

A fabric material, usually of woven cotton but of synthetic fibers also,
used to construct conveyor belts and filter cloths. Pryor, 3

duckbill

The name given to a shaking-type combination loading and conveying device,
so named from the shape of its loading end and which generally receives
its motion from the shaking conveyor to which it is attached. BCI

duckbill loader

See:shaker-shovel loader

duckbill operator

In bituminous coal mining, one who operates a small power shovel that has
a round-nosed scoop, called a duckbill, to load coal into cars in a mine.
DOT

duckbill pick

A duckbill-shaped coal-cutter pick that is forged by the roller type of
machine from dies and is the type largely used today. The machine shaping
of the pick ensures uniformity. It gives a constant clearance as the point
wears down and is particularly suitable for fused-carbide tipping.
Nelson

duckfoot

A pipe bend at the bottom of a shaft column or rising main fitted with a
horizontal base sufficiently strong for the weight of the rising main to
rest upon it. Also called duckfoot bend. BS, 10

duckfoot bend

See:duckfoot

duck machine

An arrangement of two boxes, one working within the other, for forcing air
into mines. Zern

duck's-nest tuyere

A tuyere having a cupped outlet. Standard, 2

ducktownite

An intimate mixture of pyrite and chalcocite or the matrix of a blackish
copper ore containing grains of pyrite, Tennessee.

ducon

Abbrev. for dust concentrator, which is a device used to collect dry
cuttings ejected from a borehole in which air or gas is used as a
circulation medium. Long

duct

A pipe or tubing used for auxiliary ventilation in a mine. Generally
constructed of coated fabric, metal, or fiberglass.

duct fan

An axial-flow fan mounted in, or intended for mounting in, a section of
duct. See also:tube-axial fan; vane-axial fan;
mine ventilation auxiliary fan.

ductile

a. Said of certain metals and other substances that readily deform
plastically.
b. Said of a rock that is able to sustain, under a given set of
conditions, 5% to 10% deformation before fracturing or faulting.
AGI
c. In mineralogy, capable of considerable deformation, esp. stretching,
without breaking; said of several native metals and occasionally said of
some tellurides and sulfides. AGI
d. Pertaining to a substance that readily deforms plastically. AGI
e. Capable of being permanently drawn out without breaking; such as, a
ductile metal. Webster 3rd

ductile cast iron

High-carbon ferrous product containing spheroidal graphite.
Bennett

ductile crack propagation

Slow crack propagation that is accompanied by noticeable plastic
deformation and requires energy to be supplied from outside the body.
ASM, 1

ductility

The ability of a material to deform plastically without fracturing.

ducting

Sections of air duct. See also:ventilation tubing

dudgeonite

A calcian variety of annabergite, (Ni,Ca)3 (AsO4 )2
.8H2 O, in which about one-third of the nickel is replaced by
calcium; Pibble Mine, Scotland.

due

The amount of royalty or ore payable to the lord of the manor or owner of
the soil. Fay

duff

a. Fine dry coal (usually anthracite) obtained from a coal-preparation
plant. The size range is 3/16 to 0 in (4.8 to 0 mm). See also:gum;
slack. Nelson
b. Smalls, usually with an upper size limit of 3/8 in (9.5 mm).
BS, 4
c. Term used among British miners for a fine mixture of coal and rock.
Tomkeieff
d. Aust. The fine coal left after separating the lumps; very fine
screenings; dust.
e. Coal dust and other unsaleable small coal produced in anthracite mines.
See also:anthracite fines

duffer

Aust. An unproductive claim or mine. Hess

Duff furnace

A furnace used for the manufacture of producer gas. Fay

dufrenite

A monoclinic mineral, Fe2+ Fe3+4 (PO4 )
3 (OH)5 .2H2 O ; forms green botryoidal crusts
commonly associated with limonite in gossans. Syn:kraurite;
green iron ore.

dufrenoysite

A monoclinic mineral, Pb2 As2 S5 ; sp gr, 5.6; in
crystalline dolomite in the Binnental, Switzerland.

duftite

An orthorhombic mineral, PbCu(AsO4 )(OH) ; adelite group; sp gr,
6.4; at Tsumeb, Namibia.

duin

A gold-washing dish used in Jashpur, India.

dukeway

Som. A method of hoisting coal on an incline from the working face to the
pit bottom by a rope attached to the winding engine at surface in such a
way that while the cage is going up, the empty trams are running down the
incline, and as the cage descends the loaded cars are brought up to the
shaft.

dull

a. Brist. Slack ventilation; insufficient air in a mine.
b. As applied to the degree of luster of minerals, means those minerals in
which there is a total absence of luster, as chalk or kaolin.

dull attritus

A field term denoting the degree of luster of attrital coal as it compares
to the brilliant luster of vitrain associated in the same locality.
CF:bright attritus

dull-banded coal

Coal consisting of vitrain and durain with more or less minor clarain and
minor fusain. AGI

dull coal

a. Any coal that absorbs the greater part of incident light instead of
reflecting it. Stopes recognizes two kinds of dull coal--durain and
fusain. Tomkeieff
b. The constituent of banded coal macroscopically somewhat grayish in
color, of a dull appearance, less compact than bright coal, and breaking
with a rather irregular fracture. It consists mainly of two kinds of
material; thin black bands interlayed by a lighter colored
granular-appearing matter. Microscopically, it consists of smaller
anthraxylon constituents together with a few other constituents, such as
cuticles and barklike constituents embedded in a general matrix, the
attritus. AGI
c. A variety of banded coal containing from 20% to 0% of pure, bright
ingredients (vitrain, clarain, and fusain), the remainder consisting of
clarodurain and durain. AGI

dulong

A Malayan term for hardwood pan shaped like a section of the surface of a
sphere and used as a miner's pan in prospecting, sample washing, and
manual concentration of cassiterite. See also:pan

dumb barge

A barge similar to a hopper barge, frequently used to take dredged
material from a dredger to the dumping ground. Hammond

dumb'd

Choked or clogged, as a grate or sieve in which the ore is beneficiated.
Fay

dumb drift

a. A passage leading from an airway to a point in a shaft some distance
above an inset to allow the ventilating current to bypass a station where
skips or cages are loaded. BS, 8
b. A roadway driven through the waste in longwall mining to provide
packing material. Nelson

dumb furnace

A ventilating furnace in which the foul flammable air from remote parts of
the mine enters the upcast higher up than the hot gases from the fire.
Webster 2nd

dumb screen

A chute in which there are no meshes or bars for separating the coal, and
down which the run-of-mine coal passes from the tubs direct to the railway
wagon. It is used in small mines where the coal is sold as loaded
underground or at mines where the coal is conveyed by wagon to a central
coal-preparation plant. Nelson

dummy

a. A short piece of core or core-size cylinder of rubber or other material
placed in the core lifter in an empty core barrel to guide the first part
of a newly cut core into the core lifter. Syn:guide core
b. A cathode, usually corrugated to give variable current densities, which
is plated at low current densities to remove preferentially impurities
from a plating solution. ASM, 1
c. A substitute cathode that is used during adjustment of operating
conditions. ASM, 1

dummy elevator

A second elevator for boosting tailings to higher stacking levels.

dummy gate

N. of Eng. A small gate made on the face between the mother gate and
tailgate for the purpose of getting stone to make strip packs for roof
support (when goaf roof is supported and not allowed to cave).
Trist

dummy locator

One whose name is used by a locator to secure for the latter's benefit a
greater area of mineral land than is allowed by law to be appropriated by
a single person, and any location made in pursuance of such a scheme or
device is without legal support and void. Ricketts

dummy maker

In bituminous coal mining, a laborer who fills paper cartridges
(cylinders) with clay, adobe, or rock dust, used for stemming (tamping
clay or other material on top of explosives) drill holes in the working
face to be blasted down. DOT

dumontite

A monoclinic mineral, Pb2 (UO2 )3 O2 (PO (sub
4) )2 .5H2 O ; yellow; secondary; radioactive.

dumortierite

An orthorhombic mineral, Al7 (BO3 )(SiO4 )3 O
3 ; fibrous or radiating; Mohs hardness, 7 to 8-1/2; in schists,
gneisses, and pegmatite dikes.

dumortierite quartz

A massive, blue, violet-blue, or blue-black, opaque variety of quartz
colored by intergrown crystals of dumortierite.

Dumoulin process

A method whereby copper is deposited on a rotating mandrel and later
stripped off as a long strip, which is then drawn into wire without
recasting. Liddell

dump

a. A pile or heap of ore, coal, or waste at a mine.
b. The point where a face conveyor discharges its coal into mine cars.
Nelson
c. The tipple by which the cars are dumped. CF:tipple
d. The fall available for disposal of refuse at the mouth of a mine.

dump bailer

A bailer used in borehole-cementation work, provided with a valving device
that empties the contents of the bailer (cement) at the bottom of a
borehole. Also called liquid dump bailer. Long

dumpcart

A cart having a body that can be tilted or a bottom opening downward for
emptying the contents without handling. Webster 3rd

dumped fill

Excavated material transported and dumped in a heap, generally to
preestablished lines and grades. Should be kept free of tree stumps,
organic matter, trash, and sod if any future use of the filled area is
contemplated. Carson, 1

dump equipment

One of many conveyances that carry and then dump rock or ore. Generally
trucks in surface mining and shuttle cars in underground mining.
SME, 1

dumper

A wheeled car with an elevated turntable on which is a track. A mine car
run on the upper, horizontally revolving track can be dumped sidewise or
endwise. Also called hurdy girdy. Zern

dump hook

A chain grabhook having a lever attachment for releasing it.
Webster 3rd

dump house

The building where the loaded mine cars are emptied into the chutes.
Fay

dumping bucket

A lifting bucket with a tilt or drop bottom. Standard, 2

dumping wagon

See:dumper

dump leaching

Term applied to dissolving and recovering minerals from subore-grade
materials from a mine dump. The dump is irrigated with water, sometimes
acidified, which percolates into and through the dump, and runoff from the
bottom of the dump is collected and mineral in solution is recovered by a
chemical reaction. Commonly used to recover gold and copper.
See also:heap leaching

dumpling

A mass of ground left undisturbed until the final stages of excavation,
when it is removed. In the intermediate stages it may be used as a support
for timbering to the excavations. Hammond

dump motorman

In bituminous coal mining, one who operates a mine locomotive (motor) to
haul cars of dirt, rock, slate, or other refuse to the dump at the surface
of an underground mine. Also called dirt-dump engineer; refuse engineer.
DOT

dump room

Space available for disposing of waste from a mine.

dump skip

A skip with an attachment that dumps the load automatically. Fay

dump wagon

A large-capacity side-, bottom-, or end-discharge wagon (or skip) on tired
wheels or crawler tracks; usually tractor towed. Nelson

dundasite

An orthorhombic mineral, PbAl2 (CO3 )2 (OH)
4 .H2 O ; secondary; in aggregate tufts of minute, radiating
needles.

dunite

Peridotite in which the mafic mineral is almost entirely olivine, with
accessory chromite almost always present. Named by Hochstetter in 1864
from Dun Mountain, New Zealand. AGI

Dunkard series

Continental strata, including thin coal seams, similar to the
Pennsylvanian, but of Permian age, occurring in North America. Strata of
the same age are marine in Kansas, but include marginal red beds with
gypsum, and thick salt deposits were formed later in the Kansas Basin.
CTD

duns

A term used in SW England for a shale or massive clay associated with
coal. AGI

dunstone

a. A term used near Matlock, England, for a hard granular yellowish or
cream-colored magnesian limestone. AGI
b. A term used in Wales for a hard fireclay or underclay, and in England
for a shale. AGI

Duobel

Trademark for high-velocity permissible explosives furnished in seven
grades based upon velocity and cartridge count; poor water resistance.
Used for mining coal where lump coal is not a factor. CCD, 2

duoflex checker system

A checker arrangement for hot-blast stoves. The gas used is only partially
cleaned and may contain from 0.5 to 1.5 g of dust per cubic meter of gas.
The top zone of the checkers is formed of straight-walled vertical
passages, and the middle zone of vertical passages in each of which two
opposite walls are continuously curved and the other two are straight,
while the bottom zone is formed of vertical passages in each of which all
four walls are continuously curved. Osborne

duplex breaker

A breaker having more than one crushing chamber.

duplex channeler

A type of channeling machine that cuts two channels simultaneously.

duplex compressor

Two compressors, side by side, and made in the combination of simple steam
and simple air cylinder, simple steam and compound air cylinders, or
compound steam and compound air cylinders.
See also:air-conditioning process

duplexing (duplex process)

Any two-furnace melting or refining process. ASM, 1

duplex pick

A coal-cutter pick that allows a cut to be made in either direction
without turning the pick. It is drop forged with a tip of fused tungsten
carbide. Nelson

duplex pump

A positive displacement pump with two water or liquid cylinders side by
side and geared so that the piston strokes in the cylinders alternate.
Such a pump may be either single or double action, depending on the number
and placement of intake and discharge valves on the cylinder and may be
designed so as to deliver a low volume of liquid at high pressures.
CF:centrifugal pump; triplex pump. Long

duplex pump

Displacement pump for handling pulps. Two cylinders are so geared that one
piston falls while other rises. Can lift small tonnages to good heights.
Pryor, 3

duplex steel

Steel produced by first refining it in a Bessemer converter and afterward
completing the process in an open-hearth furnace. Mersereau, 2

duplex Talbot process

A combination of the duplex and the Talbot continuous process. Molten
steel from the Bessemer converter, already freed of its carbon, silicon,
and manganese contents, is charged into the Talbot furnace. As this molten
steel is poured through the oxidized slag, the phosphorus is removed
almost immediately. Sometimes pig iron is poured in afterwards, which
raises the carbon content of the bath and aids in its deoxidation. A
portion of the heat can usually be tapped about an hour after this
addition. Osborne

duplex wire

Two insulated-copper leading wires wrapped together with paraffined cotton
covering. Fay

duplicate sampling

The placing of alternate samples of coal or ore in different containers
that are then analyzed separately. Each container thus holds a
representative subsample taken at intervals throughout the sampling
intervals or period. Nelson

Dupont process

A heavy-liquid minerals separation process in which organic liquids of
high specific gravity, known as parting liquids, are used. With sp gr 1.00
to 2.96 and very low viscosities, they serve ideally for the medium in the
sink-and-float separation of solid materials. This process is used to
clean run-of-mine anthracite, refuse banks, or mixtures of the two. The
sizes of anthracite coal that can be cleaned are No. 1 buckwheat, and
larger. This includes sizes up through broken. See also:parting liquid
Mitchell

durability

a. The capacity of a gem to withstand abrasion, impact, and chemical
alteration.
b. The rate of deterioration of foundry sand due to dehydration of its
contained clay.

durain

The term was introduced by M.C. Stopes in 1919 to designate the
macroscopically recognizable dull bands in coals. Bands of durain are
characterized by their gray to brownish-black color and rough surface with
dull or faintly greasy luster; reflection is diffuse; they are markedly
less fissured than bands of vitrain, and generally show granular fracture.
In humic coals, durain occurs in bands up to many centimeters in
thickness. Widely distributed, but with exceptions not abundant.
CF:fusain; vitrain. See also:attritus; hards. IHCP

durangite

A monoclinic mineral, NaAl(AsO4 )F ; occurs with cassiterite at the
Barranca tin mine, Durango, Mexico.

duricrust

A general term for a hard crust on the surface of, or layer in the upper
horizons of, a soil in a semiarid climate. It is formed by the
accumulation of soluble minerals deposited by mineral-bearing waters that
move upward by capillary action and evaporate during the dry season.
See also:ferricrete; silcrete; calcrete; caliche. Etymol: Latin durus,
hard, + crust. CF:hardpan

durionizing

A process of electrodepositing hard chromium on the wearing surfaces of
parts as a protection against wear by friction. Osborne

durite

a. Term for the microlithotype consisting principally of the following
groups of macerals: inertinite (micrinite, fusinite, semifusinite, and
sclerotinite) and exinite, particularly sporinite. Durite contains at
least 95% inertinite and exinite. The proportions of these two groups of
macerals may vary widely, but each must be greater than the proportions of
vitrinite and neither must exceed 95%. Durite E and durite I connote
durites rich in exinite and inertinite, respectively. It is found in many
coals, in fairly thick bands, principally in durains and the duller type
of clarain, generally common. IHCP
b. A coal microlithotype that contains a combination of inertinite and
exinite totalling at least 95%, and containing more of each than of
vitrinite. CF:durain

duroclarain

A rock-type coal consisting of the maceral vitrinite (telinite or
collinite) and large quantities of other macerals, mainly micrinite and
exinite. Micrinite is present in lesser quantities than is true with
clarodurain. CF:clarodurain

duroclarite

a. This term was introduced in 1956 by the Nomenclature Subcommittee of
the International Committee for Coal Petrology to designate the
microlithotype with maceral composition between those of clarite and
durite but closer to clarite than durite. Further specification is that
the proportion of vitrinite must exceed that of inertinite. It occurs in
fairly thick bands, and is widely distributed and, like clarodurite, is a
common constituent of most humic coals. The technological properties of
duroclarite are intermediate between those of clarite and durite, but
because of the predominance of vitrinite over inertinite they resemble
those of clarite more closely than those of durite. IHCP
b. Coal microlithotype intermediate between clarite and durite; vitrinite,
exinite, and inertinite each exceed 5% and the last is less abundant than
vitrinite. AGI
c. A coal microlithotype containing at least 5% each of vitrinite,
exinite, and inertinite, with more vitrinite than inertinite and exinite.
It is a variety of trimacerite, intermediate in composition between
clarite and durite, but closer to clarite. CF:clarodurite

durovitrain

Vitrain with minute inclusions of durain. CF:vitrodurain

Durville process

A casting process that involves rigid attachment of the mold in an
inverted position above the crucible. The melt is poured by tilting the
entire assembly, causing the metal to flow along a connecting launder and
down the side of the mold. ASM, 1

dussertite

A trigonal mineral, BaFe3 (AsO4 )2 (OH)5 ;
crandallite group; forms green to yellow-green rosettes or crusts.

dust

See:ash

dust barrier

See:stone-dust barrier

dust catcher

a. A device attached to the collar of a borehole to catch or collect dry,
dustlike rock particles produced in dry-drilling a borehole. CF:ducon
Long
b. Any device in which dust is collected or extracted from furnaces,
gases, etc.

dust chamber

a. An enclosed flue or chamber filled with deflectors, in which the
products of combustion from an ore-roasting furnace are passed, the
heavier and more valuable portion settling in the dust chamber and the
volatile portions passing out through the chimney or other escape.
Fay
b. Room air system, flue or dust extractor, where larger particles can
drop out of stream of gas and be periodically removed. Used in conjunction
with cyclones, electrostatic precipitators, and bag filters.
Pryor, 3

dust cloud

Coal or other dust particles carried in suspension in the air by currents
and eddies. Rice, 2

dust cloud flammability

The flammability of a coal-dust cloud is its ability to promote spreading
flames away from the source of ignition. Sinclair, 1

dust collection

Removal from atmosphere of mill or from transfer points where dust is
thrown up. Partially closed ventilating systems are used, which
incorporate bag filters, Cottrells, cyclones, washing chambers, and spray
towers. Pryor, 3

dust collector

a. A device used on a roof bolting machine while in operation for
separating solid particles from air and accumulating them in a form
convenient for handling.
b. Device used to collect dust produced in percussion rock drilling, this
device has an exhauster operated with compressed air from the available
air system. Air laden with dust and cutting is drawn from the boreholes
through the bit holes, the hollow drill steel, the adapter, and the
suction hose into a filter. The filtered air is excavated with the spent
compressed air through an exhaust port, and dust and cuttings settle in a
removable storage tank.

dust consolidation

The binding of coal dust on roadway surfaces to prevent it becoming
airborne by any disturbance. One method is to spread calcium chloride over
the dust so that it absorbs water and forms a pasty cake that does not
rise into suspension when workers travel on the roadway.
See also:stone dust

dust counter

A portable apparatus (as the Koltze tube, an impinger, etc.) used to
measure dust concentration in a mine or mill, as a health precaution.
Pryor, 3

dust explosion

An explosion which consists of a sudden pressure rise caused by the very
rapid combustion of airborne dust. Ignition of suspensions of combustible
dusts can occur in the following ways: (1) initiation by flame or spark,
(2) propagation by a gas explosion or blasting, and (3) spontaneous
combustion. Little is known about the last-named mechanism, which is
relatively rare in mines. The most frequent causes of major coal mine
explosions in the United States today are electric arcs, open flames, and
explosives. See also:coal-dust explosion

dust extraction

The removal of solid particles suspended in gas or ambient air.
BS, 5

dust extractor

An appliance to collect or precipitate suspended dust. Dust extraction is
often necessary at coal-preparation plants, loading stations, and also
underground. The appliance may be a cyclone, fabric filter, spray tower,
scrubber, or an electrostatic separator. See also:dust precipitator;
dust trap. Nelson

dust firing

The burning of coal dust in the laboratory of the furnace. Fay

dust-free conditions

In Great Britain, the arbitrary standards laid down by the National Coal
Board in 1949 as representing comparative dust-free conditions in coal
mines. These are as follows: stone dust, 450 particles/cm3 (size
range, 0.5 to 5.0 mu m); anthracite, 650 particles/cm3 (size
range, 1 to 5 mu m); and coal, 850 particles/cm3 (size range, 1
to 5 mu m). Nelson

dust gold

Pieces of gold under 2 to 3 pennyweights (3.1 to 4.7 g); very fine gold.

dust hopper

A hopper placed underneath the scraper, rapping roller, or other belt
cleaner, to collect the dust and dirt as it is removed from the belt; any
tank or vessel to receive and retain dust. Nelson

dusting loss

a. Shortfall in expected weight of sands or finely ground materials due to
wind action or loss when transported in open trucks. Pryor, 3
b. In laboratory sampling, the loss of part of a sample undergoing test,
through leakage of particles into the atmosphere. Pryor, 4

dust-laying oil

Crude oils, heavy asphalt oils, tars, solutions of petroleum asphalt in
gas oils, liquid asphalt, and emulsions of oils and water, used for laying
dust on roads. Fay

dustless zone

A section of the mine entry from which dust has been removed as completely
as possible by scraping or sweeping, aided by a compressed-air blast.
Rice, 2

dustman

One who dumps the dust catcher or loads the dust at blast furnaces.
Fay

dustpan dredge

A dredge containing a suction head that is pulled over the underwater
ground much as a dustpan would be. About 8 in (20 cm) high, the dustpan
may be from 20 to 40 ft (3.6 to 7.1 m) long and is supplied with jets
along its face to stir up the bottom surface. Carson, 2

dust plan

A plan kept with the book in which stone-dust samples are recorded. It
shows the sampling zones in each roadway, distinguished by color, letter,
number, or mark, and identified with that roadway. Nelson

dustplate

A vertical iron plate, supporting the slag runner of an iron blast
furnace. Fay

dust precipitator

On a large scale, sinter plant gas may be cleaned by precipitators with
very high efficiencies. The dust is precipitated in a dry state, suitable
for pelletizing and feeding back onto the sinter strand.
See also:thermal precipitator

dustproofing

A surface treatment, as with oil or calcium chloride solution, to prevent
or reduce the dustiness of coal in handling. BS, 5

dust sampling

The taking of air samples to assess their degree of dustiness, either on a
mass basis or on particle count in a known volume of air. Numerous
instruments have been developed for this purpose. Dust sampling is also
necessary to assess the efficiency of stone dusting.
See also:sampling instrument; konimeter; size selector;
thermal precipitator; tyndallometer.

dust-sampling impinger

A portable instrument for collecting dust samples so that corrective
measures can be taken for dust control and the prevention of respiratory
diseases. Dust-laden air is impinged in sampling flasks by manual,
compressed air, or electrical suction devices. Dust counts are made from
the collected air at laboratories with microscopes and counting cells.
Best, 1

dust suppression

The prevention or reduction of the dispersion of dust into the air, for
example, by water sprays. BS, 5

dust-suppression jib

A coal-cutter jib designed to conduct water through ducts, or other
arrangement, to the back of the kerf, to suppress dust and reduce the
gas-ignition hazard. See also:whale-type jib

dust-suppression person

A person employed in coal mines to apply measures to allay coal dust on
mine roadways and along the coal faces. The worker also may be in charge
of dust suppression in rock drivages. See also:rock dust
Nelson

dust-suppression system

With this system, dust can be suppressed before it becomes airborne. A
series of nozzles discharge a chemical compound in a fine spray to
materially reduce the amount of water or other liquids necessary to
saturate fly ash and eliminate dust. The compound also aids in the
diffusion of the liquid dust suppressant, allowing it to penetrate deeper
into the material. This system can be used at any point in the handling of
bulk materials, wherever dust is a hazard. Best, 1

dust trap

An appliance for the dry collection of dust during drilling in rock. The
rock chippings, dust, and air are sucked from the borehole through a
rubber hose to a drum-type container with filters. The drum is discharged
and the filters renewed periodically. In some of the newer types, the dust
is extracted through the hollow drill rods.
See also:C
Nelson

dust wetting agent

Chemical compounds that aid in the control of dry dusts such as coal and
silica to help prevent explosions and respiratory injury to workers. These
compounds are of two types. One type is used in a dry state and controls
dust by absorbing moisture from the air. The second type is an agent for
increasing the wetting effectiveness of water by breaking the surface
tension and permitting the water-compound mixture to thoroughly cover the
treated area. Best, 1

Dutch drop

A haulage term for flying switch. Fay

Dutch State Mines Process

A sink-float process used principally for coal cleaning. The process uses
a water suspension of loess (a natural claylike material) in special
trough-type separators provided with a clean coal weir and a reject drag
conveyor. Kirk

dutch twill

A type of wire cloth weave; a weave in which the first shute wire crosses
over the first and second warp wires, under the third and fourth warp
wires, and the second shute wire crosses under the first warp wire, over
the second and third warp wires, under the fourth and fifth, etc.
Henderson

duttonite

A monoclinic mineral, VO(OH)2 ; forms minute pale-brown scales as
an alteration of montroseite in sandstone on the Colorado Plateau.

duty of giants

The amount of gravel that can be moved by a water cannon, or giant, in a
24-h day by a specified flow of water. The duty of giants varies
considerably with local conditions, such as the height of the gravel
banks, the nature of the gravel bedrock, head of water obtainable, size of
jet, etc. Griffith

duty of the miner's inch

The number of cubic yards of gravel that can be broken down and sent
through the sluice by 1 miner's inch of water for 24 h. It depends upon
the height of the bank, the character of the gravel and the bedrock, the
grade of the bedrock, the type of sluice, and the pressure of the water.
In well-rounded gravel without large stones, the duty of the miner's inch
is from 4.5 to 6 yd3 (3.3 to 4.6 m3 ) of gravel for 24
h. Under less favorable conditions, the duty may range from 2.8 to 4.6 yd
3 (2.1 to 3.5 m3 ) for 24 h. See also:miner's inch
Lewis

duxite

An opaque, dark-brown variety of retinite containing about 0.5% sulfur in
lignite at Dux, Bohemia, Czech Republic; is similar to muckite,
walchowite, and neudorfite.

dwarf Brinell tester

A portable ball hardness tester in which the load is applied by means of a
vise or lever. It carries a special lens for measuring the impression's
diameter and from which the Brinell hardness value can be read directly.
Osborne

Dwight-Lloyd machine

Sintering machine in which feed moves continuously on articulated grates
pulled along by chains in belt-conveyor fashion. Controlled combustion on
these grates causes the minerals to sinter. Pryor, 3

Dwight-Lloyd process

Blast roasting in which air currents are drawn downward through the ore
mass. Bennett

Dwight-Lloyd roaster

A multihearthed circular furnace, through which horizontal rabbles revolve
and move the feed across each hearth, so that it falls peripherally to the
one below and then works inward to central discharge for next hearth
below. Rising heat and air provide the roasting conditions.
Pryor, 3

dycrasite

An orthorhombic mineral, Ag3 Sb ; metallic silver-white, commonly
tarnished; sp gr, 9.74; in veins with galena, native silver, and silver
sulfosalts; an ore of silver.

dyed stones

Minerals artificially dyed to improve their color or to imitate a more
valuable stone; they usually fade or discolor and may include chalcedony,
turquoise, jadeite, opal, serpentine, and alabaster.

dye line print

A contact print that has largely replaced the blueprints. Pryor, 3

dyke

The British spelling of dike.

dynamic braking

A method of retarding an electric winder or haulage, in which a direct
current is injected into the alternating-current winder motor stator
during the deceleration period; the motor then acts as an alternator, and
the negative load of the winding cycle is absorbed as electric power and
wasted as heat in the controller. See also:electric braking
Nelson

dynamic damping

Usually found in seismographs or seismometers where damping of motion is
desired that is in proportion to the velocity of the moving mass.
AGI

dynamic geology

A general term for the branch of geology that deals with the causes and
processes of geologic phenomena; physical geology. AGI

dynamic head

The head of fluid that would statically produce the pressure of a given
moving fluid. Syn:velocity head

dynamic load

a. An alternating or variable load. Osborne
b. See:live load

dynamic metamorphism

The total of the processes and effects of orogenic movements and
differential stresses in producing new rocks from old, with marked
structural and mineralogical changes due to crushing and shearing at low
temperatures and extensive recrystallization at higher temperatures. It
may involve large areas of the Earth's crust, i.e., be regional in
character. CF:dynamothermal metamorphism; regional metamorphism.
Syn:dynamometamorphism

dynamic method

See:modulus of elasticity

dynamic penetration test

See:penetration test

dynamic positioning

Maintainence of a drill ship's position through the use of outboard
engines on opposite sides of the vessel. The position is maintained by
automatic centering in a circle of sonar reflectors placed around the
drilling target, either on the bottom or suspended by taut wire buoys.
Several drilling ships are now equipped with this facility. Mining

dynamic viscosity

See:viscosity coefficient

dynamite

a. An industrial explosive that is detonated by blasting caps. The
principal explosive ingredient is nitroglycerin. Diethyleneglycol
dinitrate, which is also explosive, is often added as a freezing-point
depressant. A dope, such as wood pulp, and an antacid, such as calcium
carbonate, are also essential. See also:blasting gelatin
such as ammonium nitrate, and fuels, such as vegetable fiber, are usually
added.
b. A general term for detonable explosives in which the principal
constituent, nitroglycerin, is contained within an absorbent substance.
"Detonable" is a significant part of the definition since there are
compositions that contain significant amounts of nitroglycerin but that
are not detonable and are not considered to be dynamite.

dynamo exploder

A powerful exploder usually operated by a vertical rack, which, on a
downward movement, drives an armature. At the end of the stroke of the
rack bar an internal short-circuiting device opens and the current
generated by the rapidly revolving armature passes into the shot-firing
circuit. See also:blasting machine; exploder. Nelson

dynamogranite

Augen gneiss containing much microline and orthoclase.

dynamometamorphism

Dynamic metamorphism.

dynamometer

Appliance used in engineering to measure power as output, input, or
transitional. Pryor, 3

Dynamon

A permissible explosive of the ammonium nitrate group. Stoces

dynamothermal metamorphism

A common type of metamorphism involving the effects of directed pressures
and shearing stress as well as a wide range of confining pressures and
temperatures. It is related both geographically and genetically to large
orogenic belts, and hence is regional in character.
CF:regional metamorphism; dynamic metamorphism. AGI

Dynobel No. 2

A high-strength, low-density permitted explosive; no water resistance. It
is used for coal blasting in a machine-cut seam of medium hardness in dry
conditions. Nelson

dyscrasite

A natural antimonide of silver, Ag3 Sb ; color and streak,
silver-white; luster, metallic; usually tarnished; Mohs hardness, 3.5 to
4; sp gr, 9.74; found in Germany, France, and Canada. An ore of silver.
Syn:antimonial silver

dyscrystalline

See:microcrystalline

dysluite

A brown variety of gahnite containing manganese and iron in Massachusetts
and New Jersey.

dysprosia

See:dysprosium oxide

dysprosium oxide

A rare-earth oxide; white; Dy2 O3 ; isometric; sp gr, 7.81
(at 27 degrees C); and melting point, 2,340+ or -10 degrees C. Used as a
nuclear-reactor control-rod component and a neutron-density indicator.
Syn:dysprosia

dystome spar

See:datolite

dystomic

Having an imperfect fracture or cleavage. Fay

dzhalindite

An isometric mineral, In(OH)3 ; an alteration of indite; associated
with cassiterite ores.

dzhezkazganite

Possibly an amorphous lead rhenium sulfide found in the Dzhezkazgab copper
ores, Kazakhstan.