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Appendix:Dictionary of Mining, Mineral, and Related Terms/D/3

dig-down pit
 * A pit that is below the surrounding area on all sides. Also called sunken pit.

digenite
 * An isometric mineral, Cu (sub 9) S (sub 5) ; 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.

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. c. A machine for removing coal from the bed of streams, the coal having washed down from collieries of culm banks above.

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.

digging cycle
 * Complete set of operations a machine performs before repeating them.

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.

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.

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.

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

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.

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.

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.

dilatational wave
 * See: P wave; compressional wave.

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

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.

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.

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.

diluent
 * a. That which dilutes or makes more fluid; a fluid that weakens the strength or consistency of another fluid upon mixing.

b. Waste rock in ore. c. In solvent extraction, the inert liquid used to dissolve the extractant.

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.

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.

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., CaCO (sub 3) as trigonal calcite and as orthorhombic aragonite. Noun: dimorph. Adj: dimorphic. CF: trimorphism; polymorphism.

dimorphite
 * An orthorhombic mineral, As (sub 4) S (sub 3) ; 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.

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.

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

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, CaMgSi (sub 2) O (sub 6) ; 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, CuSiO (sub 2) (OH) (sub 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.

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.

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. d. The direction of the true or steepest inclination. e. The lower workings of a mine. f. The slope of layers of soil or rock. g. A dip entry, dip room, etc. A heading driven to the full rise in steep mines. 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. i. In mines, the increase in depth of a moored mine case, due to current force against the case and cable.

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.

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.

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.

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

diphead
 * A drift inclined along the dip of a coal seam.

diphead level
 * a. A mine level connecting an engine shaft with the rooms or chambers.

b. The main level, drift, or slope.

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

dip meter
 * a. An instrument used to record the amount and direction of the dip of strata exposed in the sides of a borehole.

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.

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.

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 (super -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.

dipole moment
 * Product of the dipole charge and the dipole length.

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.

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.

b. Standard revolving dipper shovel.

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. See also: geophysical exploration.

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.

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.

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.

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.

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.

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. CF: stripped plain.

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.

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.

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.

b. Underhand excavations in which miner works downward and lifts spoil to removal point. Not self-draining.

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.

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.

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.

direct firing
 * a. The combustion of coal effected by burning directly on a grate.

b. A method of firing wherein the products of combustion come in contact with the ware.

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.

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.

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.

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.

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.

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.

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

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.

b. The direction of the principal line on a photograph.

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.

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.

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.

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.

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.

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.

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. Also called direct-acting haulage.

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.

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.

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.

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.

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. See also: glare.

discard
 * a. The material extracted from the raw coal and finally thrown away. Also called dirt; stone.

b. The portion of an ingot cropped off to remove the pipe and other defects. Also called crop.

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.

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.

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. See also: 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.

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.

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.

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.

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.

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.

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

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.

dish
 * a. See: pan; gold pan.

b. The landowner's part of the ore. 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.

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.

disintegrate
 * a. To break up by the action of chemical and/or mechanical forces.

b. To separate or decompose into fragments; to break up; hence, to destroy the wholeness, unity, or identity.

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.

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.

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.

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.

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.

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.

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.

dislocation
 * a. Displacement.

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. c. The offset in a borehole. Also called deviation; throw. d. A general term to describe a break in the strata, for example, a fault. A washout is a disturbance but not a dislocation. e. The displacement of rocks on opposite sides of fracture. f. In metallurgy, the structural defect in metal or crystal produced by distortion. g. A linear crystal defect.

disorder
 * A state where different ions are distributed randomly in identical structural positions. See also: long-range order. Ant: 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.

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.

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

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.

dispersibility of dust
 * The ease with which dust is raised into suspension.

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. 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.

dispersion
 * a. The fairly permanent suspension of finely divided but undissolved particles in a fluid.

b. The creation of a dispersion by deflocculation. 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.

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.

dispersoid
 * A body dispersed in a liquid.

disphenoid
 * a. In crystallography, a solid bounded by eight isosceles triangles.

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. Syn: bisphenoid. Adj. disphenoidal.

displaced seam
 * A coal seam that has been dislocated by a fault.

displacement
 * a. The lateral movement of a point, usually at the surface, during subsidence.

b. The volume displaced by the net area of the piston multiplied by the length of the stroke. c. Sometimes used as a syn. for offset deflection; deviation; dislocation; throw. 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. e. The capacity of an air compressor, usually expressed in cubic feet of air per minute. 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. g. The volume of liquid delivered by a single stroke of a pump piston. 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.

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.

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.

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.

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

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

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.

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.

dissolution
 * a. The act or process of dissolving or breaking up, as a separation into component parts.

b. The taking up of a substance by a liquid with the formation of a homogeneous solution.

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.

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

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.

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.

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.

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. c. A process of evaporation and recondensation used for separating liquids into various fractions according to their boiling points or boiling ranges.

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.

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.

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.

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.

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. c. A coal mine is generally divided into sections or districts for purposes of ventilation and daily supervision. d. An underground section of a coal mine served by its own roads and ventilation ways; a section of a coal mine.

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.

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.

ditch
 * a. A drainage course in a mine.

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. 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.

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.

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.

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.

dithiocarbamate
 * A flotation collector agent of the general formula X (sub 2) N.CS.SM, X being hydrogen, aryl, or alkyl radical.

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.

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.

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

diurnal inequality
 * a. The departure easterly or westerly from the mean value of the declination for the day.

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.

diurnal variation
 * a. The daily variation in the earth's magnetic field.

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.

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.

diversion valve
 * A valve that permits flow to be directed into any one of two or more pipes.

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.

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

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.

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.

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.

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.

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

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.

dixenite
 * A trigonal mineral, CuMn (sub 14) Fe(AsO (sub 3) ) (sub 5) (SiO (sub 4) ) (sub 2) (AsO (sub 4) )(OH) (sub 6) ; forms nearly black aggregates of thin folia; at Laangban, Sweden.

djalmaite
 * A former name for uranmicrolite. See also: microlite.

djurleite
 * A monoclinic mineral, Cu (sub 31) S (sub 16) ; 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).

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).

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.

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

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.

b. A makeshift, temporary repair. c. As used in the mining industry, to salt.

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.

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.

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.

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. e. Any of various devices for holding, gripping, or fastening something. See also: chair; dog; catch; wing. f. A drag for the wheel of a vehicle. g. A device attached to the workpiece by means of which the work is revolved.

dog-and-chain
 * An iron lever with a chain attached by which props are withdrawn.

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.

b. An English term for any large, lumpy mass of sandstone longer than it is broad, with steep rounded sides.

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.

b. An iron bar with a bent prong used in handling logs.

doghouse
 * a. The structure enclosing the drill platform and machine.

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.

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.

b. An abrupt bend or kink in a wire rope or cable. c. An abrupt bend in a path, piping system, or road.

dogleg severity
 * Same as deflection angle; hole curvature.

dogs
 * a. Eng. In the plural; bits of wood at the bottom of an air door.

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.

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.

dole
 * A division of a parcel of ore. Also spelled dol.

dolerite
 * a. In the United States, a syn. of diabase.

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.

dolerophanite
 * A monoclinic mineral, Cu (sub 2) (SO (sub 4) )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."

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. c. To break up quartz with a piece of wood shod with iron, in order to be able to wash out the gold. d. A tool used to sharpen drills. e. See: car. f. A wooden disk for stirring the ore in a dolly tub, in order to 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.

dolly wheels
 * Pairs of wheels used to support rods of a Cornish pump working on a slope.

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

dolomite
 * a. A trigonal mineral, [CaMg(CO (sub 3) ) (sub 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.

b. Containing magnesium; e.g., dolomitic lime containing 30% to 50% magnesium.

dolomitic limestone
 * a. A limestone that has been incompletely dolomitized.

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, H (sub 8) V (sub 6) O (sub 16) ; 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.

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.

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. 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. 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. 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.

b. Sized coal for use in houses. See also: house coal. c. Coal used in country of origin; not for foreign consumption.

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.

domeykite
 * An isometric mineral, Cu (sub 3) 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.

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

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.

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.

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.

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.

b. Any one of a large number of unscientific devices with which it is claimed water, mineral, and oil deposits can be located. 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.

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.

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. 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. d. To apply a lubricant to drill rods, rod couplings, open gears, etc. e. To doctor a drill diamond. See also: doctor. f. A rubberlike compound applied to granite surfaces before inscriptions are cut in the granite. g. A viscous liquid put on pipe threads to make a tight joint. h. Slang for mold lubricant.

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.

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.