Appendix:Dictionary of Mining, Mineral, and Related Terms/A/4

AQ
 * A letter name specifying the dimensions of bits, core barrels, and drill rods in the A-size and Q-series wireline diamond drilling system having a core diameter of 27 mm and a hole diameter of 48 mm.

aqua ammonia
 * Ammonia water; esp., a solution of ammonia containing 10% ammonia by weight.

aqua regia
 * A very corrosive, fuming, yellow liquid made by mixing nitric and hydrochloric acids, usually in the proportion of one part by volume of pure nitric acid with three parts by volume of pure hydrochloric acid. Used in dissolving metals such as gold and platinum and in etching. Syn: nitrohydrochloric acid; nitromuriatic acid.

aquarium test
 * A test conducted by detonating a standard quantity of explosives under water and measuring both the detonation and gas pressures using transducers; useful for evaluating the relative strengths of various explosives.

aqueous
 * a. Of, or pertaining to, water.

b. Made from, with, or by means of water; e.g., aqueous solutions. c. Produced by the action of water; e.g., aqueous sediments.

aqueous fusion
 * Melting in the presence of water, as a magma.

aqueous liquor
 * In the ion-exchange (IX) process, the feed to the exchange columns. In solvent extraction, the aqueous feed containing the metal values to be extracted into the organic phase.

aquiclude
 * A body of relatively impermeable rock that is capable of absorbing water slowly but does not transmit it rapidly enough to supply a well or spring. CF: confining bed. See also: aquitard.

aquifer
 * a. A formation, a group of ions, or a part of a formation that is water bearing.

b. A stratum or zone below the surface of the Earth capable of producing water, as from a well. c. An underground stratum that will yield water in sufficient quantity to be of value as a source of supply. An aquifer is not a stratum that merely contains water, for this would apply to all strata in the ground-water area. An aquifier must yield water. See also: aquitard.

aquifer test
 * In situ procedure, such as single-well (bail test or slug test) and multiple-well pumping tests, used to determine hydraulic properties of an aquifer.

aquifuge
 * a. Suggested by Bedier, as the opposite of aquifer.

b. A rock that contains no interconnected openings or interstices and therefore neither absorbs nor transmits water. CF: confining bed.

aquitard
 * Low-permeability bed, in a stratigraphic sequence, of sufficient permeability to allow movement of contaminants, and to be relevant to regional ground-water flow, but of insufficient permeability for the economic production of water. See also: aquifer; aquiclude. CF: confining bed.

aragonite
 * a. An orthorhombic mineral, 4[CaCO (sub 3) ] ; acicular, pyramidal, tabular, reniform, columnar, or stalactitic habit; formed from hot carbonated water in springs, cavities in basalt, or biogenetically in shells and pearls (mother of pearl). Syn: aragon spar.

b. The mineral group aragonite, cerussite, strontianite, and witherite.

aragonite sand
 * Sand-size grains of predominantly aragonite (CaCO (sub 3) ) found in shallow, tropical waters. Aragonite forms by chemical precipitation in sea water due to the presence of SO (sub 4) ions.

Aragon spar
 * Former name for aragonite.

aramayoite
 * A triclinic mineral, Ag(Sb,Bi)S (sub 2) ; iron black with perfect cleavage; at Chocaya, Bolivia.

arbitrage
 * An operation that involves a purchase in one market with the simultaneous sale of an equivalent quantity in another market, (e.g., the London Metal Exchange and the New York Commodity Exchange), and the necessary foreign exchange transaction to protect against any change in the parities between the two currencies involved.

arborescent
 * Applied to minerals having a treelike form, esp. when fairly massive. If the mineral formation is so thin as to resemble a painting of a tree, it is generally called dendritic. Syn: dendriform; dendritic.

arcanite
 * An orthorhombic mineral, K (sub 2) SO (sub 4).

arc cutter
 * A device consisting of a bit attached to knuckle-jointed rods used to drill a curved borehole or branched holes from a parent borehole. Syn: Thompson arc cutter. CF: whipstock.

arc furnace
 * A furnace in which material is heated either directly by an electric arc between an electrode and the work, or indirectly by an arc between two electrodes adjacent to the material.

arch
 * a. A portion of rock left standing at the intersection of a mine wall and roof, to support the roof.

b. Curved roof of underground opening. See also: dome. c. A curved structural member used to span openings or recesses; also built flat. Structurally, an arch is a piece or assemblage of pieces so arranged over an opening that the supported load is resolved into pressures on the side supports and practically normal to their faces. d. A part of a furnace; a crown. e. To heat a pot in a pot arch. f. One of the five chambers of a brick kiln; also, the fire chamber in certain kinds of furnaces and ovens. g. The roof of a reverberatory furnace.

arch blocks
 * Applied to the wooden voussoirs used in framing a timber support for the tunnel roof, when driving a tunnel on the so-called American system. These blocks are made of plank, superimposed in three or more layers, and a breaking joint.

Archean
 * Said of the rocks of the Archeozoic.

arched
 * Corn. Said of the roads in a mine, when built with stones or bricks.

Archeozoic
 * The earlier part of Precambrian time, corresponding to Archean rocks. Also spelled: Archaeozoic.

arch forms
 * Forms or patterns on which sprung arch bricks are laid to ensure the proper arch contour.

arch girder
 * A normal H-section steel girder bent to a circular shape. The usual form consists of halves joined together at the crown by bolts and two fishplates. The arch girder is usually splay legged or straight legged in shape, but horseshoe shapes are also in use. See also: steel support; wood stilt.

Archimedes' principle
 * The statement in fluid mechanics that a fluid buoys up a completely immersed solid so that the apparent weight of the solid is reduced by an amount equal to the weight of the fluid that it displaces.

arching
 * a. Arch.

b. Curved support for roofs of openings in mines; constructed archways in masonry. c. The development of peripheral cracks around an excavation due to the difference in stress between the skin rock and the rock in the stress ring. See also: V-arching. d. The folding of schists, gneisses, or sediments into anticlines. e. The transfer of stress from a yielding part of a soil or rock mass to adjoining less yielding or restrained parts of the mass. f. The fretting away of the periphery of a rock tunnel, usually converting it from a rectangular to a circular or elliptical section. The effect in the back is sometimes referred to as the "natural arch." The putting in of a lining built to an arch shape should not be referred to as arching but as "lining" or "putting in the arch."

arching action
 * The natural process by which a fractured, pulverulent, or plastic material acquires a certain amount of ability to support itself partially through the resolution of the vertical component of its weight into diagonal thrust.

arching to a weakness
 * See: V-arching.

arch rib
 * The main load-bearing member of a ribbed arch.

arch set
 * Steel assemblies used to support mine workings.

arch structure
 * See: abutment; pressure arch.

arcose
 * See: arkose.

arc shear machine
 * See: universal machine.

arc shooting
 * A method of refraction seismic prospecting in which the variation of travel time (velocity) with azimuth from a shot point is used to infer geologic structure. The term also applies to a refraction spread placed on a circle or a circular arc with the center at the shot point.

Arctic suite
 * A group of basaltic and associated igneous rocks intermediate in composition between rocks of the Atlantic suite and the Pacific suite. CF: Atlantic suite; Pacific suite.

arcwall machine
 * See: slabbing machine.

arc welding
 * A group of welding processes wherein coalescence is produced by heating with an electric arc or arcs, with or without the application of pressure and with or without the use of filler metal.

Ardeer double-cartridge test
 * See: sensitivity to propagation.

ardennite
 * a. A yellow to yellowish-brown vanadiosilicate of aluminum and manganese that crystallizes in the orthorhombic system.

b. An orthorhombic mineral, Mn (sub 4) (Al,Mg) (sub 6) (SiO (sub 4) ) (sub 2) (Si (sub 3) O (sub 10) )[(As,V)O (sub 4) ](OH) (sub 6).

areal geology
 * The branch of geology that pertains to the distribution, position, and form of the areas of the Earth's surface occupied by different types of rock or by different geologic units, and to the making of geologic maps.

areal map
 * A geologic map showing the horizontal area or extent of rock units exposed at the surface.

areal pattern
 * A dispersion pattern resulting from widespread rock alteration. Such patterns may outline the boundaries of a group of deposits and thus limit the area that it is necessary to prospect in detail.

area of airway
 * In mine ventilation, the cross-sectional area of the entry or duct through which the air flows; expressed in square meters.

area of influence of a well
 * The area surrounding a well within which the piezometric surface has been lowered when pumping has produced the maximum steady rate of flow.

area of settlement
 * The surface area affected by subsidence.

arenaceous
 * Said of a sediment or sedimentary rock consisting wholly or in part of sand-sized fragments, or having a sandy texture or the appearance of sand; pertaining to sand or arenite. Also said of the texture of such a sediment or rock. The term implies no special composition and should not be used as a syn. of siliceous. Syn: sandy.

areng
 * A Bornean term for a yellowish gravelly earth, sometimes containing diamonds.

arenite
 * a. A general name for sedimentary rocks composed of sand-sized fragments irrespective of composition; e.g., sandstone, graywacke, arkose, and calcarenite.

b. A clean sandstone that is well sorted, contains little or no matrix material, and has a relatively simple mineralogic composition; specif. a pure or nearly pure, chemically cemented sandstone containing less than 10% argillaceous matrix and inferred to represent a slowly deposited sediment well-washed by currents.---Etymol: Latin arena, sand. Adj. arenitic. See also: lutite.

Arents tap
 * An arrangement by which molten lead from the crucible of a shaft furnace is drawn through an inverted siphon into an exterior basin from which it can be ladled without disturbing the furnace. Syn: siphon tap.

arfvedsonite
 * A monoclinic mineral, Na (sub 3) (Fe (super +2) ,Mg) (sub 4) Fe (super +3) Si (sub 8) O (sub 22) (OH) (sub 2), of the amphibole group; dark green to black; in silica-poor igneous rocks.

Argall furnace
 * A reverberatory roasting furnace the hearth of which has a reciprocating movement whereby the ore is caused to move forward by the action of rabbles extending across the hearth.

Argall tubular furnace
 * A tubular roasting furnace consisting of four brick-lined steel tubes 30 ft (9.1 m) long nested together inside two steel tires, which revolve upon steel-faced carrying rolls.

argental mercury
 * See: amalgam.

argentate
 * a. A salt in which silver acts as an acid radical; e.g., ammonium argentate (fulminating silver).

b. Having a silvery appearance.

argentation
 * The act or process of coating or plating with silver.

argentiferous
 * Containing silver.

argentiferous galena
 * See: silver lead ore.

argentiferous lead
 * Lead that contains silver.

argentine
 * a. A lamellar variety of calcite with a pearly white luster.

b. Silver-coated white metal. c. A finely divided tin moss or sponge obtained from a solution of tin by precipitation with zinc. d. Adj. pertaining to, containing, or resembling silver; silvery.

argentite
 * An orthorhombic mineral, Ag (sub 2) S ; isometric above 180 degrees C; dimorphous with acanthite; massive or as coating; metallic lead-gray; soft, sectile; sp gr, 7.3; in veins with other silver and sulfide minerals; commonly pseudomorphous after acanthite; an important ore of silver. Syn: silver glance; vitreous silver; argyrite.

argentojarosite
 * A trigonal mineral, AgFe (sub 3) (SO (sub 4) ) (sub 2) (OH) (sub 6) ; alunite group; yellow to brown-yellow.

argentopyrite
 * An orthorhombic mineral, AgFe (sub 2) S (sub 3) ; dimorphous with sternbergite.

argil
 * a. Potter's clay; white clay.

b. See: aluminite.

argillaceous
 * a. Pertaining to, largely composed of, or containing clay-size particles or clay minerals, such as an argillaceous ore in which the gangue is mainly clay; esp. said of a sediment (such as marl) or a sedimentary rock (such as shale) containing an appreciable amount of clay. Syn: clayey. See also: argillic.

b. Pertaining to argillite.

argillaceous hematite
 * A brown to deep-red variety of natural ferric oxide containing an appreciable portion of clay (or sand). Syn: ironstone clay.

argillaceous limestone
 * A limestone containing an appreciable amount (but less than 50%) of clay; e.g., cement rock.

argillaceous ore
 * Ore in which the gangue is mainly clay.

argillaceous rock
 * A sedimentary rock composed of clay-grade particles; i.e., composed of minute mineral fragments and crystals less than 0.002 mm in diameter; containing much colloidal-size material. In addition to finely divided detrital matter, argillaceous rocks consist essentially of illite, montmorillonite, kaolinite, gibbsite, and diaspore.

argillation
 * The development of clay minerals by the weathering of aluminum silicates. CF: kaolinization.

argillic
 * Pertaining to clay or clay minerals; e.g., argillic alteration in which certain minerals of a rock are converted to minerals of the clay group. CF: argillaceous.

argillite
 * A compact rock, derived either from mudstone (claystone or siltstone), or shale, that has undergone a somewhat higher degree of induration than mudstone or shale but is less clearly laminated and without its fissility, and that lacks the cleavage distinctive of slate.

argillization
 * The replacement or alteration of feldspars to form clay minerals, esp. in wall rocks adjacent to mineral veins. CF: kaolinization.

argon
 * A colorless, odorless, monatomic, inert gas. Symbol, Ar. Obtained by the fractionation of liquid air. Used in electric light bulbs and in fluorescent tubes.

argulite
 * A variety of asphaltic sandstone.

argyrite
 * Former name for argentite; also called argyrose.

argyrodite
 * An orthorhombic mineral, Ag (sub 8) GeS (sub 6) ; pseudocubic; forms a series with canfieldite.

argyropyrite
 * A discredited term for a silver-iron sulfide, probably argentopyrite.

argyrose
 * Former name for argentite.

argyrythrose
 * Former name for pyrargyrite.

arite
 * A nickel mineral between nickeline and breithauptite in composition.

arithmetic-mean particle diameter
 * A measure of the average particle size obtained by summing the products of the size-grade midpoints times the frequency of particles in each class, and dividing by the total frequency.

Arizona ruby
 * A deep-red or ruby-colored variety of pyrope garnet of igneous origin, Southwestern United States.

arizonite
 * a. A hexagonal mineral, Fe (sub 2) Ti (sub 3) O (sub 9) ; in irregular metallic steel-gray masses in pegmatite veins near Hackberry, AZ. Formerly called pseudorutile.

b. A mixture of hematite, rutile, ilmenite, and anatase. c. An ore of micaceous iron, silver iodide, gold, iron sulfides, and antimony in a vein in Yavapai County, AZ. d. A hypabyssal rock with 80% quartz, 18% alkali feldspar, and accessory mica and apatite in Arizona (not a rock name in the IUGS classification).

Arkansas diamond
 * A diamond from Murfreesboro, AR.

Arkansas stone
 * A variety of novaculite found in the Ouachita Mountains of western Arkansas. Also, a whetstone made of Arkansas stone. See also: novaculite.

arkansite
 * A brilliant, iron-black variety of brookite from Magnet Cove, AR.

arkose
 * A feldspar-rich sandstone, typically coarse-grained and pink or reddish, that is composed of angular to subangular grains that may be either poorly or moderately well sorted; usually derived from the rapid disintegration of granite or granitic rocks, and often closely resembles granite; e.g., the Triassic arkoses of the Eastern United States. Quartz is usually the dominant mineral, with feldspar (chiefly microcline) constituting at least 25%. Cement (silica or calcite) is commonly rare, and matrix material (usually less than 15%) includes clay minerals (esp. kaolinite), mica, and iron oxide; fine-grained rock fragments are often present. Arkose is commonly a current-deposited sandstone of continental origin, occurring as a thick, wedge-shaped mass of limited geographic extent (as in a fault trough or a rapidly subsiding basin); it may be strongly cross-bedded and associated with coarse granite-bearing conglomerate, and it may denote an environment of high relief and vigorous erosion of strongly uplifted granitic rocks in which the feldspar was not subjected to prolonged weathering or transport before burial. Arkose may also occur at the base of a sedimentary series as a thin blanketlike residuum derived from and resting on granitic rock. Etymol: French, probably from Greek archaios, ancient, primitive. Syn: arkosic. CF: graywacke; feldspathic sandstone; subarkose. Also spelled arcose.

arkose quartzite
 * See: arkosite.

arkosic
 * Having the character of arkose.

arkosic sandstone
 * A sandstone with considerable feldspar, such as one containing minerals derived from coarse-grained quartzo-feldspathic rocks (granite, granodiorite, gneiss) or from highly feldspathic sedimentary rocks; specif. a sandstone containing more than 25% feldspar and less than 20% matrix material of clay, sericite, and chlorite. See also: arkosite.

arkosite
 * A quartzite with a notable amount of feldspar. Syn: arkose quartzite. See also: arkosic sandstone.

arm
 * The inclined member or leg of a set or frame of timber.

armangite
 * A trigonal mineral, Mn (sub 26) As (sub 18) O (sub 50) (OH) (sub 4) (CO (sub 3) ) ; black; near Laangban, Sweden.

arm conveyor
 * A conveyor consisting of an endless belt, or one or more chains, to which are attached projecting arms, or shelves, for handling packages or objects in a vertical or inclined path.

armenite
 * a. A hexagonal mineral, BaCa (sub 2) Al (sub 6) Si (sub 9) O (sub 30) .2H (sub 2) O ; osumilite group.

b. Former name for azurite, Armenian stone.

armor
 * An outer cable covering that may be either metallic or nonmetallic.

armored apron
 * An apron in which each pan is provided with a separate wearing plate.

armored cable
 * A cable that is wrapped with metal, usually steel wires or tapes, primarily for physical protection. See also: cable.

armored flexible conveyor
 * A heavy, chain-type flexible conveyor capable of being advanced with the face without dismantling. It is designed either to carry a coal cutter or a cutter loader or to guide and hold a plow against the face. It may be advanced by horizontal hydraulic rams that are fixed at about 20-ft (6-m) intervals on the waste side of the conveyor. It is often employed on prop-free-front faces with hand filling, and it has a capacity of about 200 to 300 st/hr. Syn: Panzer conveyor. See also: conveyor; chain conveyor; face conveyor.

armored relict
 * An unstable relict enveloped by a crystal or by a reaction shell which revented its reaction with the other constituents of the rock. See also: unstable relict.

Armstrong air breaker
 * See: compressed-air blasting.

arnimite
 * Orthorhombic Cu (sub 5) (SO (sub 4) ) (sub 2) (OH) (sub 6) .3H (sub 2) O ; perhaps the mineral antlerite.

arochlors
 * Chlorinated diphenyl materials that are useful as vehicles for pigments used in glass decoration since they volatilize without leaving a carbon residue. Arochlors provide a grinding and dispersing medium for nonaqueous slurries of pigments and ceramic bodies; also, they can be used in combination with waxes to provide moisture-proof coatings.

aromatic compound
 * A compound derived from the hydrocarbon benzene, C (sub 6) H (sub 6), distinguished from that derived from methane, CH (sub 4).

aromatic hydrocarbon
 * A compound of carbon and hydrogen that contains in its molecular structure a closed and saturated ring of carbon atoms; e.g., benzene, naphthalene, and anthracene.

aromatite
 * A bituminous stone resembling a fragrant gum resin in color and odor. It was a precious stone in ancient Arabia and Egypt.

arquerite
 * A soft, malleable, silver-rich variety of amalgam containing about 87% silver and 13% mercury; from Coquimbo, Chile.

arrastra
 * See: arrastre.

arrastre
 * A circular rock-lined pit in which broken ore is pulverized by stones attached to horizontal poles fastened in a central pillar and dragged around the pit. Also spelled arrastra.

arrested decay
 * A stage in coal formation when biochemical action ceases.

arrester
 * a. Any mechanical contrivance or device used to stop or slow up motion.

b. Mechanism for the purification of a gas stream that may contain suspended liquids or solids.

arrival dealings
 * Dealing in ores, concentrates, and metals in transit from source to market.

arrojadite
 * A monoclinic mineral, KNa (sub 4) CaMn (sub 4) Fe (sub 10) Al(PO (sub 4) ) (sub 12) (OH,F) ; dark green, forms a series with dickinsonite.

arrow
 * A sharp-pointed, thin metal rod about 1 to 2 ft (0.3 to 0.6 m) long with a ring at the other end, used in surveying; a thin metal peg.

arroyo
 * a. A term applied in the arid and semiarid regions of the Southwestern United States to the small, deep, flat-floored channel or gully of an ephemeral stream, usually with vertical or steeply cut banks of unconsolidated material at least 60 cm high; it is usually dry, but may be transformed into a temporary watercourse or short-lived torrent after heavy rainfall. CF: dry wash.

b. The small intermittent stream or rivulet that occupies such a channel.---Etymol: Spanish, stream, brook; gutter, watercourse of a street. See also: wadi; nullah.

arsenargentite
 * Possibly a silver arsenide.

arsenate
 * a. A salt or ester of an arsenic acid; a compound containing one of the three radicals in which arsenic has a +5 valence: ortho-arsenate, AsO (sub 4) ; meta-arsenate, AsO (sub 3) ; pyro-arsenate, As (sub 2) O (sub 7).

b. A mineral characterized by pentavalent arsenic and oxygen; e.g., mimetite Pb (sub 5) (AsO (sub 4) ) (sub 3) Cl. CF: vanadate.

arsenic
 * A metallic, steel-gray, brittle element. Symbol, As. Found native in realgar and orpiment, and combined with heavy metals. Used in bronzing, pyrotechny, insecticides, and poisons, and as a doping agent in transistors. Gallium arsenide is used as a laser material to convert electricity directly into coherent light. Arsenic and its compounds are poisonous.

arsenical antimony
 * See: allemontite.

arsenical nickel
 * See: nickeline; niccolite.

arsenical pyrite
 * See: arsenopyrite.

arsenic bloom
 * See: arsenolite; pharmacolite.

arsenicite
 * See: pharmacolite.

arsenic trioxide
 * A white, odorless, tasteless powder; AsO (sub 3) . Used in the manufacture of pigments, glass, and other arsenic compounds, ceramic enamels, and aniline colors; mixed with soda ash for boiler compounds. Syn: white arsenic; arsenious oxide.

arsenious oxide
 * See: arsenic trioxide.

arsenite
 * A mineral characterized by trivalent antimony and oxygen; e.g., trigonite, Pb (sub 3) Mn(AsO (sub 3) ) (sub 2) (AsO (sub 2) (OH).

arsenobismite
 * A yellowish-green mineral, Bi (sub 2) (AsO (sub 4) )(OH) (sub 3).

arsenoclasite
 * An orthorhombic mineral, Mn (sub 5) (AsO (sub 4) ) (sub 2) (OH) (sub 4) ; red, from Laangban, Sweden. Also spelled arsenoklasite.

arsenolamprite
 * An orthorhombic mineral arsenic; dimorphous with arsenic.

arsenolite
 * An isometric mineral, As (sub 2) O (sub 3) ; dimorphous with claudetite. Syn: arsenic bloom.

arsenopyrite
 * a. A monoclinic mineral, 8[FeAsS] ; pseudo-orthorhombic, prismatic, and metallic silver-white to steel gray; the most common arsenic mineral and principal ore of arsenic; occurs in many sulfide ore deposits, particularly those containing lead, silver, and gold. Syn: mispickel; arsenical pyrite; white pyrite; white mundic.

b. The mineral group arsenopyrite, glaucodot, gudmundite, osarsite, and ruarsite.

arsenosulvanite
 * An isometric mineral, Cu (sub 3) (As,V)S (sub 4) ; forms a series with sulvanite. Syn: lazarevicite.

arsenpolybasite
 * A monoclinic mineral, (Ag,Cu) (sub 16) (As,Sb) (sub 2) S (sub 11) . Also spelled arsenopolybasite. CF: antimonpearceite.

arsenuranocircite
 * Syn: heinrichite It is not clear which name has priority as applied to a natural mineral. See also: metaheinrichite.

arsenuranylite
 * The orthorhombic mineral, Ca(UO (sub 2) ) (sub 4) (AsO (sub 4) ) (sub 2) (OH) (sub 4) .6H (sub 2) O ; typically orange-red.

arterial road
 * A main road with secondary roads joining it.

artesian
 * a. Refers to ground water under sufficient hydrostatic head to rise above the aquifer containing it.

b. Pertaining to underground water that is confined by impervious rock or other material under sufficient pressure to raise it above the upper level of the saturated rock or other material in which it occurs, if this rock or material is penetrated by wells or natural fissures. Formerly, the term was applied only to water under sufficient pressure to raise it to the surface of the Earth.

artesian aquifer
 * An aquifer that contains artesian water.

artesian basin
 * A geologic structural feature or a combination of such features in which water is confined under artesian pressure.

artesian discharge
 * The process of discharge from a well by artesian pressure, and also the quantity of water discharged. The artesian pressure is aided by the buoyancy of the natural gas that enters some wells with the water.

artesian leakage
 * The slow percolation of water from artesian formations into the confining materials of a less permeable but not of a strictly impermeable character. Such percolation causes a reduction in artesian pressure, depending on the relative impermeability of the materials in the confining formations.

artesian spring
 * A spring, the water from which issues under artesian pressure, generally through some fissure or other opening in the confining bed that overlies the aquifer.

artesian water
 * a. Ground water that is under sufficient pressure to rise above the level at which it is encountered by a well, but that does not necessarily rise to or above the surface of the ground.

b. Ground water that is confined within a permeable bed and that rises under pressure to approx. the height of the intake. If the outlet (well or spring) is appreciably below the height of the intake, the water will flow out under pressure. If even with or above the height of the intake, the water will rise in the well but it will not flow out.

artesian well
 * a. A well in which the water level rises above the top of the aquifer, whether or not the water flows at the land surface.

b. Formerly, only applied to a well drilled to a depth where, owing to the structure of the strata, the water pressure was high enough to raise the water to the surface. c. Often applied to any deep well, even where pumping is necessary, as in an ordinary driven well. See also: well.

arthurite
 * a. An apple-green monoclinic mineral, CuFe (sub 2) (AsO (sub 4) ,PO (sub 4) ,SO (sub 4) ) (sub 2) (O,OH) (sub 2) .4H (sub 2) O.

b. The mineral group arthurite, earlshannonite, ojuelaite, and whitmoreite.

articulite
 * See: itacolumite.

artificial aging
 * Aging above room temperature. See also: precipitation heat treatment.

artificial brine
 * Brine produced from an underground deposit of salt or other soluble rock material in the process of solution mining. CF: brine.

artificial horizon
 * A device for indicating the horizontal, as a bubble, gyroscope, pendulum, or the flat surface of a liquid. It is sometimes simply called a horizon. Syn: false horizon.

artificial island
 * An island that is constructed by humans rather than formed by natural means, usually in waters less than 30 m deep. In the mining industry they are commonly used to support the construction of service or ventilation shafts for underground mines extending offshore.

artificial liquid fuel
 * Fuel created by the hydrogenation of coal; the destructive distillation of coal, lignite, or shale at low temperature; and by a recombination of the constituents of water gas in the presence of a suitable catalyst.

artificial refractories
 * Materials manufactured in electric furnaces and used for special purposes; e.g., zirconium carbide, titanium carbide, and silicon carbide.

artinite
 * A snow-white monoclinic mineral, Mg (sub 2) (CO (sub 3) )(OH) (sub 2) .3H (sub 2) O.

asbestiform
 * Said of a mineral that is fibrous, i.e., like asbestos.

asbestine
 * a. A silicate of magnesium much used in paint. It serves as an aid in holding paint pigment in solution and in binding paint films together. Also marketed under such names as French chalk and talc. Syn: agalite.

b. Of, pertaining to, or having the characteristics of asbestos; incombustible.

asbestos
 * a. A commercial term applied to silicate minerals that separate readily into thin, strong fibers that are flexible, heat resistant, and chemically inert, thus making them suitable for uses (as in yarn, cloth, paper, paint, brake linings, tiles, insulation, cement, fillers, and filters) where incombustible, nonconducting, or chemically resistant material is required. Since the early 1970's, there have been serious enviromental concerns about the potential health hazards of asbestos products, which has resulted in strong enviromental regulations.

b. Any asbestiform mineral of the serpentine group (chrysotile, best adapted for spinning and the principal variety in commerce) or amphibole group (esp. actinolite, anthophyllite, gedrite, cummingtonite, grunerite, riebeckite, and tremolite). c. A term strictly applied to asbestiform actinolite. Syn: asbestus; amianthus; earth flax; mountain flax; rock wool.

asbestosis
 * A lung disease caused by breathing asbestos dust.

asbestos minerals
 * Certain minerals that have a fibrous structure, are heat resistant and chemically inert, possess high electrical insulating qualities, and are of sufficient flexibility to be woven. The two main groups are serpentine and amphiboles. Asbestos proper is actinolite. Chrysotile is fibrous serpentine; amosite is fibrous anthophyllite; crocidolite is fibrous soda-amphibole. Used in fireproof buildings, insulating, paint materials, brake linings, and clutches, and as insulation against heat, electricity, and acid.

asbestos yarn
 * Yarn consisting of asbestos fiber; asbestos and vegetable fibers; asbestos and vegetable fibers and wire; or asbestos and vegetable fibers with an insert of cotton or other yarn reinforcement. Metallic asbestos yarn is yarn consisting of plain asbestos yarn twisted with brass, copper, or other fine wire.

asbestus
 * See: asbestos.

asbolan
 * A hexagonal mineral, (Co,Ni) (sub 1-y) (MnO (sub 2) ) (sub 2-x) (OH) (sub 2-2y+2x) .nH (sub 2) O ; a soft, black, earthy aggregate commonly classed as a variety of "wad," the cobalt content reaching as high as 32% (40% cobalt oxide). Syn: asbolane; asbolite; black cobalt; cobalt ocher; wad.

asbolane
 * A form of wad; a soft, earthy manganese dioxide, containing up to about 32% cobalt oxide. Sometimes referred to as earthy cobalt. Syn: asbolite; cobalt ocher. See also: asbolan.

asbolite
 * See: asbolan; asbolane.

ascensional ventilation
 * A mine ventilation system in which the fresh intake air flows down to the bottom end of the workings and then ascends along the faces to the main return. See also: descensional ventilation; antitropal ventilation; homotropal ventilation.

ascension theory
 * A theory of hypogene mineral-deposit formation involving mineralizing solutions rising through fissures from magmatic sources in the Earth's interior. CF: descension theory.

ascharite
 * See: szaibelyite.

aschisite
 * An igneous rock with the same chemical composition as its parent magma, i.e., undifferentiated. CF: diaschistic.

aschistic
 * Said of the rock of a minor intrusion that has a composition equivalent to that of the parent magma, i.e., in which there has been no significant differentiation. CF: diaschistic.

ash
 * a. The inorganic residue after burning, esp. of coal. Ignition generally alters both the weight and the composition of the inorganic matter. See also: ash yield; extraneous ash; inherent ash.

b. Fine pyroclastic material (under 2.0-mm diameter; under 0.063-mm diameter for fine ash). The term usually refers to the unconsolidated material but sometimes is also used for its consolidated counterpart, tuff. Syn: dust; volcanic ash; volcanic dust; pumicite. c. Inorganic residue remaining after ignition of combustible substances, determined by definite prescribed methods.

ashcroftine
 * A tetragonal mineral, K (sub 5) Na (sub 5) (Y,Ca) (sub 12) Si (sub 28) O (sub 70) (OH) (sub 2) (CO (sub 3) ) (sub 8) .3H (sub 2) O ; occurs in small pink needles at Narsarsuk, Greenland.

ash curve
 * A graph that shows a relation between the specific gravity of fractions of a coal sample floated in liquids of step-by-step increased density, and the percentage of ash in each such fraction. Syn: tromp curve.

ash drawers
 * Early name applied to tourmaline because of its polar electrostatic property.

ash error
 * The difference between the percentage ash of a product of a separation and that shown by the washability curve (based on the reconstituted feed) of a product with the same properties (usually percentage of ash).

ash fusibility
 * A measure, in terms of temperature, of fusion of coal ash prepared and tested under standard conditions.

ash-fusion temperature
 * The temperature at which a special test cone made from particles of ash obtained from the coal will (1) begin to deform, i.e., soften, or (2) completely deform or fuse into a blob.

ashlar
 * Rectangular pieces of stone of nonuniform size that are set randomly in a wall.

ash-specific gravity curve
 * The curve obtained from the float-and-sink analysis by plotting the ash contents of successive fractions against specific gravity.

ashstone
 * An indurated deposit of fine volcanic ash.

ash yield
 * The percentage of material remaining after a fuel is burned; that portion of a laboratory sample remaining after heating under standard conditions to constant weight; i.e., until all the combustible matter has been burned away. See also: ash; extraneous ash; inherent ash.

asparagolite
 * See: asparagus stone.

asparagus stone
 * A yellow-green variety of apatite. Syn: asparagolite.

aspect
 * a. The gross or overall lithologic or biologic characteristics of a stratigraphic unit as expressed at any particular point.

b. The angle made by a target with the line joining it to the observation point is known as the aspect of the target.

asperolite
 * A variety of chrysocolla, containing more than the usual percentage of water.

asphaltic
 * Pertaining to or containing asphalt; e.g., asphaltic limestone or asphaltic sandstone impregnated with asphalt, or asphaltic sand representing a natural mixture of asphalt with varying proportions of loose sand grains.

asphaltic ore
 * Asphaltlike ore carrying invisible uranium values.

asphaltic rock
 * Any rock naturally impregnated with asphalt. It is generally sandstone or limestone.

asphaltite
 * Any one of the naturally occurring black solid bitumens that are soluble in carbon disulfide and fuse above 230 degrees F (110 degrees C). Examples are uintahite, glance pitch, and grahamite.

asphalt rock
 * A porous rock, such as a sandstone or limestone, that is impregnated naturally with asphalt. Syn: asphalt stone; rock asphalt.

asphalt stone
 * See: asphalt rock.

asphyxiate
 * To suffocate; to choke.

aspirating
 * See: dedusting.

aspirator
 * An apparatus for moving or collecting gases, liquids, or granular substances by suction.

assay
 * a. To analyze the proportions of metals in an ore; to test an ore or mineral for composition, purity, weight, or other properties of commercial interest. Syn: crucible assay.

b. The test or analysis itself; its results.

assay balance
 * A very sensitive balance used in the assaying of gold, silver, etc., for weighing the beads. It usually has magnifying lenses for reading the graduations. See: balance.

assayer
 * Person who analyzes ores and alloys, esp. bullion, to determine the value and properties of their precious metals.

assay foot
 * In determining the assay value of an orebody, the multiplication of its assay grade by the number of feet along which the sample was taken. CF: assay inch; assay value.

assay grade
 * The percentage of valuable constituents in an ore, determined from assay. CF: assay value; value.

assay inch
 * In determining the assay value of an orebody, the multiplication of its assay grade by the number of inches along which the sample was taken. CF: assay foot; assay value.

assay office
 * A laboratory for examining ores, usually gold and silver ores, in order to determine their economic value.

assay plan
 * Map of a mine showing the assay, stope, width, etc., of samples taken from positions marked. Used to control grade and quality of ore mined and milled.

assay plan factor
 * In sampling, a term used to describe the rate that the head value bears to the mine sampling. This percentage figure is useful in reducing any extant or subsequent mine-sampling average to that which in actual production it will likely prove to be. In South Africa this is generally known as the "mine call factor." Syn: correction factor.

assay split
 * Agreed average value, as between buyer's and seller's assay, used as pricing basis in sale of mineral.

assay ton
 * A weight of 29.166+ g, used in assaying to represent proportionately the assay value of an ore. Because it bears the same ratio to 1 mg that a ton of 2,000 lb bears to the troy ounce, the weight in milligrams of precious metal obtained from an assay ton of ore equals the number of ounces to the ton. Abbrev. AT.

assay value
 * a. The quantity of an ore's valuable constituents, determined by multiplying its assay grade or percentage of valuable constituents by its dimensions. CF: assay inch; assay foot. The figure for precious metals is generally given in troy ounces per ton of ore, or per assay ton. See also: assay grade; value.

b. The monetary value of an orebody, calculated by multiplying the quantity of its valuable constituents by the market price. Syn: average assay value.

assay walls
 * The outer limits to which an orebody can be profitably mined, the limiting factor being the metal content of the country rock as determined from assays.

assembled stone
 * Any stone constructed of two or more parts of gem materials, whether genuine, synthetic, imitation, or a combination thereof; e.g., a doublet or triplet. Syn: composite stone; imitation.

assembly rod
 * An external bolt holding a machine together.

assessment
 * See: assessment work.

assessment drilling
 * Drilling done to fulfill the requirement that a prescribed amount of work be done annually on an unpatented mining claim to retain title.

assessment labor
 * Refers to the annual labor required of the locator of a mining claim after discovery (and not to work done before discovery).

assessment work
 * The annual work upon an unpatented mining claim on the public domain necessary under U.S. law for the maintenance of the possessory title thereto. This work must be done each year if the claim is to be held without patenting. Syn: assessment; location work.

asset
 * Property with cash sale value. In mining, the dominant asset is the proved ore reserve.

assigned protection factor
 * a. The expected workplace level of respiratory protection that would be provided by a properly functioning respirator or a class of respirators to properly fitted and trained users. Abbrev. APF.

b. The minimum anticipated protection provided by a properly functioning respirator or class of respirators to a given percentage of properly fitted and trained users.

assimilation
 * The incorporation and digestion of solid or fluid foreign material, such as wall rock, in magma. The term implies no specific mechanisms or results. Such a magma, or the rock it produces, may be called hybrid or contaminated. See also: hybridization. CF: differentiation. Syn: magmatic assimilation; magmatic dissolution.

assistant mine foreman
 * A person employed to assist the mine foreman in the performance of his or her duties and to serve in his or her place, in the absence of the mine foreman.

Assmann psychrometer
 * A wet-and-dry-bulb hygrometer in which air is drawn over the thermometer bulbs by an integral fan.

association
 * See: rock association.

association placer location
 * A placer location made by an association of persons in one location covering 160 acres (64 ha) is not eight locations covering 20 acres (8 ha) each. It is in law a single location, and as such a single discovery is sufficient to support such a location; the only assessment work required is as for a single claim.

assured mineral
 * See: reserves.

astatic
 * Not taking a fixed or definite position or direction; as an instrument in which a negative restoring force has been applied so as to aid any deflecting force, thereby rendering the instrument more sensitive and/or less stable.

astatic gravimeter
 * A gravity meter or gravimeter constructed so that a high sensitivity is achieved at certain positions of the elements of the system; i.e., equilibrium between a negative restoring force and the force of gravity at such positions. See also: gravimeter.

astatic pendulum
 * A pendulum having almost no tendency to take a definite position of equilibrium.

astatization
 * The application of a restoring force to a moving element of a physical system in such a manner as to drive the moving element away from its rest position and to aid any deflecting force, so as to increase sensitivity.

asteria
 * Any gemstone that, when cut en cabochon in the correct crystallographic direction, displays a rayed figure (a star) by either reflected or transmitted light; e.g., star sapphire. Syn: star stone. See also: star sapphire.

asteriated
 * a. Like a star, with rays diverging from a center.

b. Said of a mineral, crystal, or gemstone that exhibits asterism; e.g., asteriated beryl. See: star.

asteriated quartz
 * Quartz having whitish or colored radiations within the crystals. See: star quartz.

asteriated topaz
 * Asteriated yellow variety of corundum, wrongly called Oriental topaz.

asterism
 * a. Starlike rays of light observed in some minerals when viewed from certain directions, particularly if the mineral is cut en cabochon. Minerals having this feature are called asteriated or star. Asteriated beryl, chrysoberyl, crocidolite, emerald, quartz, ruby, and sapphire are known.

b. A starlike effect observed in certain minerals either by transmitted or by reflected light. c. Elongation of Laue X-ray diffraction spots produced by stationary single crystals as a result of internal crystalline deformation. The size of the Laue spot is determined by the solid angle formed by the normals to any set of diffracting planes; this angle increases with increasing crystal deformation, producing progressively elongated (asteriated) spots. Measurements of asterism are used as indicators of deformation in crystals subjected to slow stress or to shock waves. CF: corundum cat's eye.

asthenolith
 * A body of magma that was formed by melting in response to heat generated by radioactive disintegration.

asthenosphere
 * The layer or shell of the Earth below the lithosphere, which has reduced yield strength, permitting viscous or plastic flow under relatively small stresses; it is a zone in which isostatic adjustments take place, magmas may be generated, and seismic waves are strongly attenuated. It is a part of the upper mantle. Syn: zone of mobility. See also: stereosphere.

ASTM coal classification
 * A system based on proximate analysis in which coals containing less than 31% volatile matter on the mineral-matter-free basis (Parr formula) are classified only on the basis of fixed carbon; i.e., 100% volatile matter. They are divided into five groups: above 98% fixed carbon; 98% to 92% fixed carbon; 92% to 86% fixed carbon; 86% to 78% fixed carbon; and 78% to 69% fixed carbon. The first three of these groups are called anthracites, and the last two are called bituminous coals. The remaining bituminous coals, the subbituminous coals, and the lignites are then classified into groups as determined by the calorific value of the coals containing their natural bed moisture; i.e., the coals as mined but free from any moisture on the surface of the lumps. The classification includes three groups of bituminous coals with moist calorific value from above 14,000 Btu/lb (32.5 MJ/kg) to above 13,000 Btu/lb (30.2 MJ/kg); three groups of subbituminous coals with moist calorific value below 13,000 Btu/lb to below 8,300 Btu/lb (19.3 MJ/kg); and two groups of lignitic coals with moist calorific value below 8,300 Btu/lb. The classification also differentiates between consolidated and unconsolidated lignites and between the weathering characteristics of subbituminous and lignitic coals. See also: coal classification systems.

astochite
 * A blue to gray-violet variety of amphibole; at Wermland, Sweden. Locally known as blue rhodonite. Syn: soda richterite.

astrakanite
 * See: blodite.

astridite
 * An ornamental stone, consisting mainly of chromojadeite. From Manokwari, New Guinea.

astringent
 * a. A taste that puckers the mouth; descriptive of certain minerals, such as alum.

b. Causing contraction, shrinking, or puckering. c. Said of a clay containing an astringent salt.

astrophyllite
 * a. A triclinic mineral, (K,Na) (sub 3) (Fe,Mn) (sub 7) Ti (sub 2) Si (sub 8) O (sub 24) (O,OH) (sub 7) ; forms a series with kupletskite.

b. A mineral group.

asymmetrical
 * a. Without symmetry.

b. Said of mineral crystals having no center, plane, or axis of symmetry.

asymmetrical vein
 * A vein with unlike mineral sequences on either side.

asymmetric class
 * The class of crystal forms without any symmetry.

asymmetric fold
 * A fold in which one limb dips more steeply than the other. If one limb is overturned, the term "overturned fold" or "overfold" is used. CF: symmetrical fold.

asymmetric unit
 * The whole group of prototype atoms that, where repeated by the symmetry operations of a space group, generate a crystal structure. CF: unit cell.

atacamite
 * An orthorhombic mineral, 4[Cu (sub 2) Cl(OH) (sub 3) ] ; trimorphous with paratacamite and botallackite; grass green, in fine crystal aggregates, fibrous or columnar; a supergene mineral in oxidized zones of copper deposits in desert regions; a source of copper. Syn: remolinite.

ataxic
 * Said of an unstratified mineral deposit. CF: eutaxic.

atelestite
 * A monoclinic mineral, Bi (sub 8) (AsO (sub 4) ) (sub 3) O (sub 5) (OH) (sub 5) ; yellow.

at grade
 * See: graded.

Atkinson
 * The resistance of a section of roadway in which there is a pressure of 1 lb/ft (super 2) (6.9 kPa) throughout the section, when an amount of 1,000 ft (super 3) /s (1 kilocusec or 28.3 m (super 3) /s) of dry air at 60 degrees F (15.6 degrees C) and 30 in (762 mm) barometer is passing. See also: Atkinson's friction coefficient.

Atkinson's friction coefficient
 * The measure of the pressure expended per 1,000 ft/min per square foot of surface traversed in order to create motion under the conditions prevailing. It is expressed as pounds per square foot per 1,000 ft/min. See also: Atkinson.

Atlantic suite
 * One of two large groups of igneous rocks, characterized by alkalic and alkali-calcic rocks. Harker (1909) divided all Tertiary and Holocene igneous rocks of the world into two main groups, the Atlantic suite and the Pacific suite, the former being so named because of the predominance of alkalic and alkali-calcic rocks in the nonorogenic areas of crustal instability around the Atlantic Ocean. Because there is such a wide variety of tectonic environments and associated rock types in the areas of Harker's Atlantic and Pacific suites, the terms are now seldom used to indicate kindred rock types; e.g., Atlantic-type rocks are widespread in the mid-Pacific volcanic islands. CF: Arctic suite; Mediterranean suite.

Atlas ore
 * See: malachite.

Atlas spar
 * Syn: satin spar. Also called Atlas pearls, Atlas stone.

atmosphere
 * a. The gaseous envelope surrounding the Earth. The mixture of gases that surrounds the Earth, being held thereto by gravity. It consists by volume of 78% nitrogen, 21% oxygen, 0.9% argon, 0.03% carbon dioxide, and minute quantities of helium, krypton, neon, and xenon. The atmosphere is so compressed by its own weight that half is within 5.5 km of the Earth's surface.

b. A unit of pressure. A normal atmosphere is equal to the pressure exerted by a vertical column of mercury 760 mm in height at 0 degrees C, and with gravity taken as 980.665 cm/s (super 2). It equals 14.66 psi (101 kPa). c. In a furnace, the mixture of gases resulting from combustion. d. The kind of air prevailing in any place, as within a kiln during firing.

atmosphere-supplying respirator
 * A class of respirators that supply a respirable atmosphere, independent of the workplace atmosphere.

atmospheric condenser
 * A condenser using water at atmospheric pressure.

atoll texture
 * a. A texture sometimes observed in a thin section of a rock, in which a ring of one mineral occurs with another mineral or minerals inside and outside the ring.

b. In mineral deposits, the surrounding of one mineral by a ring of one or more other minerals; commonly results from replacement of pyrite by another mineral, with the outermost pyrite unaffected and constituting the "atoll." Syn: core texture. CF: tubercle texture.

atom
 * According to the atomic theory, the smallest particle of an element that can exist either alone or in combination with similar particles of the same element or of a different element. The smallest particle of an element that enters into the composition of a molecule.

atomic charge
 * Electrical charge density due to gain or loss of one or more electrons.

atomic distance
 * Distance between two atom centers.

atomic moisture meter
 * A device to monitor the moisture in coal passing through a preparation plant, by using radiation that is sensitive to hydrogen atoms. The coal is bombarded with neutrons, some of which strike hydrogen atoms and bounce back to a detector tube, thus providing a continuous measure of moisture content. This meter permits the moisture content of coal to be measured instantaneously, continuously, and automatically.

atomic number
 * The number of protons in the nucleus of an atom. See also: atomic weight.

atomic plane
 * a. Any one of the layers into which atoms form themselves in an orderly pattern during the growth of a crystal.

b. In a crystal, any plane with a regular array of atomic units (atoms, ions, molecules, or radicals); it has potential to diffract X-rays, to parallel a crystal face, or to permit cleavage.

atomic scattering factor
 * Describes the "efficiency" of X-ray scattering of a given atom in a given direction; equal to the amplitude of the wave scattered by an atom divided by the amplitude of the wave scattered by one electron.

atomic susceptibility
 * Change in magnetic moment of 1 g.atom on application of magnetic field of unit strength.

atomic volume
 * a. The space occupied by a quantity of an element as compared with its atomic weight. Obtained by dividing the specific gravity of the element by its atomic weight; also called specific volume.

b. The volume occupied by 1 g.atom of an element.

atomic weight
 * The average relative weight of the atoms of an element referred to an arbitrary standard of 16.0000 for the atomic weight of oxygen. The atomic weight scale used by chemists takes 16.0000 as the average atomic weight of oxygen atoms as they occur in nature. The scale used by physicists takes 16.00435 as the atomic weight of the most abundant oxygen isotope. Division by the factor 1.000272 converts an atomic weight on the physicists' scale to the corresponding atomic weight on the chemists' scale. See also: atomic number.

atomization
 * a. In powder metallurgy, the dispersion of a molten metal into particles by a rapidly moving stream of gas or liquid.

b. A patented process for producing a metallic dust, such as zinc dust.

atomized metal powder
 * Metal powder produced by the dispersion of molten metal by a rapidly moving gas, or liquid stream, or by mechanical dispersion.

atomizer
 * A spray device for producing a very fine mist for the suppression of airborne dust in mines. It is normally operated by compressed air. Syn: jet mixer; line oiler.

atopite
 * A yellow or brown variety of romeite containing fluorine. See also: romeite.

attached ground water
 * That portion of the subsurface water adhering to the pore walls. It is assumed to be equal in quantity to the pellicular water, and it is measured by specific retention.

attack rate
 * Planned rate of ore extraction from mineral deposit.

attapulgite
 * A light-green, magnesium-rich clay mineral, named from its occurrence at Attapulgus, GA, where it is quarried as fuller's earth. Crystallizes in the monoclinic system. Syn: palygorskite.

attendance signaling system
 * A signaling system that operates between the surface lamp room and the underground office, indicating the workers in attendance at the beginning of the shift. See also: self-service system.

attenuation
 * a. A reduction in the amplitude or energy of a signal, such as might be produced by passage through a filter.

b. A reduction in the amplitude of seismic waves, as produced by divergence, reflection and scattering, and absorption. c. That portion of the decrease in seismic or sonar signal strength with distance that is dependent not on geometrical divergence, but on the physical characteristics of the transmitting medium. CF: damping.

Atterberg limits
 * In a sediment, the water-content boundaries between the semiliquid and plastic states (known as the liquid limit) and between the plastic and semisolid states (known as the plastic limit). See also: consistency limits. CF: plastic limit; plasticity index.

Atterberg scale
 * A proposed particle-size scale or grade scale for the classification of sediments based on a decimal system beginning with 2 mm. The limits of the subclass are obtained by taking the square root of the product of the larger grade limits. The subdivision thus made follows the logarithmic rule. This is the accepted European standard for classification of particle size.

Atterberg test
 * A method for determining the plasticity of clay in terms of the difference between the water content when the clay is just coherent and when it begins to flow as a liquid.

attitude
 * The relation of some directional feature in a rock to the horizontal plane. The attitude of planar features (bedding, foliations, joints, etc.) is described by the strike and the dip. The attitude of a linear feature (fold axis, lineation, etc.) is described by the strike of the horizontal projection of the linear feature and its plunge.

attrital coal
 * translucent cell-wall degradation matter or translucent humic matter predominates) in which the ratio of anthraxylon to attritus is less than 1:3. See also: anthraxylous coal; attritus.

attrition
 * a. The act of wearing and smoothing of rock surfaces by the passage of water charged with sand and gravel, by the passage of sand drifts, the descent of glaciers, etc.

b. The wear and tear that rock particles in transit undergo through mutual rubbing, grinding, knocking, scraping, and bumping, with resulting comminution in size. CF: abrasion. Syn: corrasion.

attrition mill
 * a. Mill that grinds abrasively, using rubbing action rather than impact shattering to disintegrate material.

b. A disintegrator depending chiefly on impact to reduce the particle size of the charge. Attrition mills are sometimes used in the clay building materials industry to deal with the tailings from the edge-runner mill.

attritious wear
 * Wear of abrasive grains in grinding such that sharp edges gradually become rounded. A grinding wheel that has undergone such wear usually has a glazed appearance.

attritus
 * a. A composite term for dull gray to nearly black coal components of varying maceral content, unsorted and with fine granular texture, that forms the bulk of some coals or is interlayered with bright bands of anthraxylon in others. It is formed of a tightly compacted mixture of altered vegetal materials, esp. those that were relatively resistant to complete degradation. CF: attrital coal. Syn: durain. The term was introduced by R. Thiessen in 1919.

b. Thin bands of dull coal interlaminated with the bright, glossy coal bands called anthraxylon. Microscopically it consists of intimately mixed, tightly compacted remains of varied morphological form and origin. Attritus is a collective term, not directly comparable with any one of the microlitho types of the Stopes-Heerlen nomenclature but consists of an intimate association of varying proportions of macerals of the vitrinite, exinite, and inertinite groups. It is present in practically all types of coal. In bright-banded coal it is secondary in importance to anthraxylon, but in splint coal it is the dominant component, and nonbanded attrital coals consist entirely of attritus. c. The dull-gray to nearly black, frequently striped portion of material that comprises the bulk of some coals, and the alternating bands of bright anthraxylon in well-banded coals. It was derived from all sorts of comminuted and macerated plant matter, esp. from the plants that were more resistant to complete decomposition. It consists of humic degradation and opaque, charred, resinous, and mineral matter; fats, oils, waxes, cuticles, spores, arid spore exines, and other constituents of the plants forming the coal. d. Coal components consisting of a mixture of microscopic fragments of vegetable tissues. It is classified into opaque attritus and transparent attritus. Generally, it corresponds to cull coal or durain.

audiofrequency
 * Any frequency corresponding to a normal audible sound wave (ranges roughly from 15,000 to 20,000 Hz).

augelite
 * A monoclinic mineral, Al (sub 2) (PO (sub 4) )(OH) (sub 3).

augen
 * In foliate metamorphic rocks such as schists and gneisses, large lenticular mineral grains or mineral aggregates having the shape of an eye in cross section, in contrast to the shapes of other minerals in the rock. See also: augen structure. Etymol: Ger., eyes.

augen gneiss
 * A general term for a gneissic rock containing augen. See also: cataclasite.

augen schist
 * A metamorphic rock characterized by recrystallized minerals occurring as augen or lenticles parallel to and alternating with schistose streaks. See also: mylonite gneiss.

augen structure
 * In some gneissic and schistose metamorphic rocks, a structure consisting of minerals like feldspar, quartz, or garnet that have been squeezed into elliptical or lens-shaped forms resembling eyes (augen), which are commonly enveloped by essentially parallel layers of contrasting constituents such as mica or chlorite. CF: augen; flaser structure.

auger
 * a. A drill for seismic shotholes or geophone holes modeled after the conventional carpenter's screw auger. Hence, any seismic shothole drilling device in which the cuttings are continuously removed mechanically from the bottom of the bore during the drilling operation without the use of fluids. A rotary drilling device used to drill shotholes or geophone holes in which the cuttings are removed by the device itself without the use of fluids. CF: hand auger; hand boring.

b. Any of various augerlike tools designed for boring holes in wood or for boring into soil and used esp. for such purposes as mining coal, prospecting, drilling for oil or water, and digging postholes. Also, a tool for drilling holes in coal for blasting. c. Drilling using an auger. See also: coal auger; bucket auger; twist drill; horizontal auger.

auger bits
 * Hard steel or tungsten-carbide-tipped cutting teeth used in an auger run on a torque bar or in an auger-drill head run on a continuous-flight auger.

auger boring
 * The hole and/or the process of drilling a hole using auger equipment.

auger head
 * See: auger mining.

auger hole
 * A hole drilled with power-driven augers.

auger mining
 * A mining method often used by strip-mine operators where the overburden is too thick to be removed economically. Large-diameter, spaced holes are drilled up to 200 ft (61 m) into the coalbed by an auger. Like a bit used for boring holes in wood, this consists of a cutting head with screwlike extensions. As the auger turns, the head breaks the coal and the screw carries it back into the open and dumps it on an elevating conveyor; this, in turn, carries the coal to an overhead bin or loads it directly into a truck. Auger mining is relatively inexpensive, and it is reported to recover 60% to 65% of the coal in the part of the bed where it is used. Syn: auger head.

augite
 * A monoclinic mineral, 8[(Ca,Na)(Mg,Fe,Al,Ti)(Si,Al) (sub 2) O (sub 6) ] ; pyroxene group; dark-green to black with prismatic cleavage; a common rock-forming mineral in igneous and metamorphic rocks. Syn: basaltine; fassaite; pyroxene. CF: pigeonite.

augite bronzite
 * An obsolete term for a pyroxene between enstatite and augite in composition.

augite diorite
 * A diorite in which augite is a prominent mafic mineral.

augite syenite
 * A syenite in which augite is a prominent mafic mineral.

auralite
 * a. Altered iolite.

b. Altered cordierite.

aureole
 * a. A circular or crescentic distribution pattern about the source or origin of a mineral, ore, mineral association, or petrographic feature. It is encountered principally in magnetic and geochemical surveys. CF: dispersion pattern.

b. Discoloration of a mineral, viewed in thin section, in the form of a ring. Most haloes of this sort are caused by radiation damage by alpha particles emitted from uranium- and thorium-bearing mineral inclusions. c. A zone surrounding an igneous intrusion, in which the country rock shows the effects of contact metamorphism. Syn: contact zone; metamorphic aureole. d. A zone of alteration or other chemical reaction surrounding a mineral in a rock. e. See: halo.

auri-argentiferous
 * Applied to minerals containing both gold and silver.

aurichalcite
 * An orthorhombic mineral, 4[(Zn,Cu) (sub 5) (CO (sub 3) ) (sub 2) (OH) (sub 6) ] ; forms soft scaly greenish-blue crusts in oxidized zones of copper-zinc ore deposits; a guide to zinc ore.

auricupride
 * An orthorhombic mineral, Cu (sub 3) Au . Syn: gold cupride; cuproauride.

auriferous
 * Refers to a substance that contains gold, esp. gold-bearing mineral deposits.

auriferous pyrite
 * Iron sulfide, in the form of pyrite, containing gold, probably in solid solution.

aurobismuthinite
 * A doubtful sulfide containing bismuth, gold, and silver; lead-gray in color. It may be a mixture of (Bi,Au,Ag (sub 2) )S, or possibly of a gold-silver alloy, and bismuthinite, Bi (sub 2) S (sub 3) . From Nacozari, Sonora, Mex.

aurosmirid
 * A silver-white crystal solution of gold and osmium in isometric iridium.

aurostibite
 * An isometric mineral, AuSb (sub 2) ; pyrite group.

aurous
 * Of, pertaining to, or containing gold in the univalent state; e.g., aurous chloride (AuCl).

austempering
 * The isothermal transformation of a ferrous alloy at a temperature below that of pearlite formation and above that of martensite formation. Austempering is the isothermal transformation used to form a unique acicular matrix of bainitic ferrite and stable high-carbon austenite in hardenable cast irons.

austenite
 * A solid solution of one or more elements in face-centered cubic iron. Unless otherwise designated (such as nickel austenite), the solute is generally assumed to be carbon.

austenitic stainless steel
 * The so-called 18-8 grades contain from 16% to 26% chromium and 6% to 20% nickel, are not hardenable by heat treatment, and are nonmagnetic in the annealed condition.

austenitizing
 * Forming austenite by heating a ferrous alloy into the transformation range (partial austenitizing) or above the transformation range (complete austenitizing).

austinite
 * An orthorhombic mineral, CaZn(AsO (sub 4) )(OH); adelite group; forms a series with conichalcite.

Australian bentonite
 * Trade name for highly plastic clays from Trida, N.S.W.

Australian cinnabar
 * A variety of chrome red.

authigene
 * A mineral or rock constituent that was formed in place; e.g., a mineral of an igneous rock; the cement of a sedimentary rock if deposited directly from solution; or a mineral resulting from metamorphism. Syn: authigenic mineral. Ant. allogene.

authigenesis
 * a. The process by which new minerals form in place within a rock during or after its formation, as by replacement or recrystallization, or by secondary enlargement of quartz overgrowths.

b. Any process involving crystal growth in situ, i.e., subsequent to the origin of its matrix or surroundings but not a product of transformation or recrystallization, customarily reserved for low-temperature sedimentary environments. Ant. allogenesis. Adj. authigenic; authigenous. Adv. authigenous.

authigenetic
 * See: authigenic.

authigenic
 * Formed or generated in place; specif. said of rock constituents and minerals that have not been transported or that crystallized locally at the spot where they are now found, and of minerals that came into existence at the same time as, or subsequently to, the formation of the rock of which they constitute a part. The term, as used, often refers to a mineral (such as quartz or feldspar) formed after deposition of the original sediment. Syn: authigenetic. Ant. allogenic. CF: autochthonous. See also: authigenesis.

authigenic mineral
 * See: authigene.

authorized fuels
 * In Great Britain, under the regulations made by the Minister (Smoke Control Areas-Authorized Fuels-Regulations, 1956), authorized fuels include coke of all kinds, anthracite, low-volatile steam coals, Phurnacite, Coalite, Rexco, etc., as well as oil, gas, and electricity.

authorized person
 * An authorized person is either one appointed or permitted by the official designated by State mining laws to be in charge of the operation of the mine or one appointed to perform certain duties incident to generation, transformation, and distribution or use of electricity in the mine. This person shall be familiar with construction and operation of the apparatus and with hazards involved.

autochthon
 * A body of rocks that remains at its site of origin, where it is rooted to its basement. Although not moved from their original site, autochthonous rocks may be mildly to considerably deformed. CF: allochthon; stationary block. Also spelled autochthone.

autochthonous
 * Formed or produced in the place where now found. Applied to a rock the dominant constituents of which have been formed in situ; e.g., rock salt. CF: allochthonous; authigenic.

autochthonous coal
 * Coal believed to have been formed from accumulations of plant debris at the place where the plants grew. Two modes of origin are distinguished: terrestrial and aquatic. Also called indigenous coal. See also: in situ origin theory.

autochthonous peat
 * Peat that formed in place by the gradual accumulation of plant remains in water. It is subdivided into low-moor peat and high-moor peat.

autochthony
 * An accumulation of plant remains in the place of their growth. The term itself can be distinguished between autochthonous elements of growth (euautochthony) and autochthonous elements of sedimentation (hypautochthony).

autoclastic
 * Having a broken or brecciated structure, formed in the place where it is found as a result of crushing, dynamic metamorphism, or other mechanical processes; e.g., a fault breccia, or a brecciated dolomite produced by diagenetic shrinkage followed by recementation. CF: cataclastic.

autogenous
 * a. In the dense-media separation process, fluid media partly composed of a mineral species selected from material being treated.

b. Selectively sized lumps of material used as grinding media.

autogenous grinding
 * The secondary grinding of coal or ore by tumbling in a revolving cylinder with no balls or bars taking part in the operation.

autogenous roasting
 * Roasting in which the heat generated by oxidation of the sulfides is sufficient to propagate the reaction.

autohydration
 * The development of new minerals in an igneous rock by the action of its own magmatic water on already existing magmatic minerals.

autoinjection
 * See: autointrusion.

autointrusion
 * a. A process wherein the residual liquid of a differentiating magma is injected into rifts formed in the crystallized fraction at a late stage by deformation of unspecified origin. Syn: autoinjection.

b. Sedimentary intrusion of rock material from one part of a bed or set of beds in process of deposition into another part.

autolith
 * a. An inclusion in an igneous rock to which it is genetically related. CF: xenolith. Syn: cognate inclusion.

b. In a granitoid rock, an accumulation of iron-magnesium minerals of uncertain origin. It may appear as a round, oval, or elongate segregation or clot.

automatic ash analysis
 * Analysis in which the coal sample passes first to a conditioning unit, which dries and grinds it, then to an X-ray analysis unit. The analysis is based on the difference in the reflection of X-rays by the combustible and noncombustible components of the sample. The reflection is compared photoelectrically with a reference sample.

automatic belt takeup
 * A device used with certain types of belt conveyors for the taking up or storage of belt during reversible operation.

automatic clip
 * An appliance for attaching and detaching mine trams or cars without manual effort. It is generally attached at inby clipping stations and detached at the shaft bottom. See also: clip; coupling; haulage clip.

automatic clutch
 * A clutch whose engagement is controlled by centrifugal force, vacuum, or other power without attention by the operator.

automatic coupling
 * A device that automatically couples cars when they bump together.

automatic cyclic winding
 * A system of automatic winding in which the complete installation operates without human aid and winding continues automatically as long as coal is available at the shaft bottom and is cleared at the bank. Syn: cyclic winding. See also: pushbutton winding control; Ward-Leonard control; manual winding control; semiautomatic control.

automatic dam
 * See: boomer.

automatic door
 * a. A mine door operated by pressure of the locomotive wheels on a switch along the rails approaching the doors, which closes the door automatically after the trip has passed. These doors are preferable to regular mine doors. However, they must be carefully maintained to keep them in a safe operating condition.

b. A wooden door arranged to close automatically when released, by installing the door with a slight lean in the direction of closing.

automatic doors
 * Air doors on a haulage road that are automatically operated by a passing vehicle or train of tubs, or other means.

automatic feed
 * a. A hydraulic-control system of valves that when once set and without the manual assistance of a drill runner will reduce or increase feed pressure applied to a drill stem as hardness of rock penetrated changes.

b. A pneumatic rock drill equipped with a power-actuated feed mechanism.

automatic feed sampler
 * An automatic, timed sampling device used at mill feeds and other plants.

automatic heat-treating machine
 * See: Gilman heat-treating machine.

automatic pump control
 * The starting and stopping of a pump by a mechanism actuated by the level of water in the suction well or pump, or by the level or pressure of water in a discharge tank.

automatic pumping
 * An arrangement to stop and start a mine pump automatically by means of a float switch.

automatic reclosing relays
 * Relays used to automatically reclose electrically operated circuit breakers. They limit the duration of power failures in many instances where faults clear themselves quickly. Most reclosing relays attempt to close a breaker three times before locking it out. The time interval between reclosures is predetermined. Lockout means that after the third attempt fails to keep the breaker in, the relay will not function until it is reset manually. Such relays can be designed to operate more than three times before locking out, with the number of reclosures depending on the requirements and design of the system.

automatic recorder
 * Appliance for recording the working time of machines such as cutter loaders, conveyors, etc. A vibrating type, fitted on the equipment itself, marks on a chart a straight line when the machine is idle and an oscillating one when working.

automatic sampler
 * An instrument designed to take samples of mine gases or water at predetermined times or intervals.

automatic sampling
 * Automatic removal of samples at timed intervals from a passing stream of ore, pulp, or solution.

automatic sprinkler
 * A water sprinkling device closed by a metallic alloy that melts at a low temperature. In case of fire the alloy melts, releasing a water spray. These devices are used in wood-lined shafts and timbered bottoms, sometimes by legal requirements.

automatic winding
 * This term includes at least three different systems: (1) fully automatic winding in which no driver, banksman, or onsetter is employed; (2) pushbutton automatic winding, similar to the above except that the operation is started by a pushbutton by the banksman or onsetter; and (3) cyclic winding in which the driver takes off the brakes and throws over the control lever at the beginning of the wind.

autometamorphism
 * a. A process of recrystallization of an igneous rock under conditions of falling temperature, attributed to the action of its own volatiles, e.g., serpentinization of peridotite or spilitization of basalt.

b. The alteration of an igneous rock by its own residual liquors. This process should rather be called deuteric because it is not considered to be metamorphic. See also: deuteric. CF: autometasomatism.

autometasomatism
 * Alteration of a recently crystallized igneous rock by its own last water-rich liquid fraction, trapped within the rock, generally by an impermeable chilled border. CF: autopneumatolysis; autometamorphism.

automolite
 * A dark-green to nearly black variety of gahnite.

automorphic
 * a. Said of the holocrystalline texture of an igneous or metamorphic rock, characterized by crystals bounded by their own rational faces. Also said of a rock with such a texture. The term idiomorphic is more common in U.S. usage. CF: xenomorphic.

b. A synonym of euhedral, obsolete in U.S. usage, but generally preferred in European usage. Syn: automorphic-granular; euhedral.

automorphic-granular
 * See: automorphic.

autopneumatolysis
 * Autometamorphism involving the crystallization of minerals or the alteration of a rock by gaseous emanations originating in the magma or rock itself. CF: autometasomatism.

autospray
 * A device for controlling dust carried by loaded conveyors. A liquid medium is sprayed on the conveyor load only when moving and not when stationary, or when the belt is running unloaded. The spray control is placed centrally beneath the conveyor belt and a load causes the belt to deflect and rotate the driving pulley, which causes the controller valve to open. A belt stoppage or no load causes the valve to close.

autostoper
 * A stoper or light compressed-air rock drill, mounted on an air-leg support that not only supports the drill but also exerts pressure on the drill bit.

autotransformer
 * A special-type of transformer whose use in mines is limited to apparatus for starting induction motors of the squirrel cage type. The winding is a common one for primary and secondary, and the two circuits are electrically in contact with each other.

autotroph
 * Organism capable of growth exclusively at the expense of inorganic nutrients. See also: chemolithotroph; photolithotroph.

autrometer
 * a. An automatic multielement-indexing X-ray spectrograph, capable of the qualitative and quantitative determinations of as many as 24 elements in a single sample. Choice of the elements may be made from magnesium through all the heavier elements. The device measures the intensity of an emitted wavelength band from a standard sample and compares it with the intensity of a like band from an unknown sample. These data are presented in the form of a ratio of one intensity to the other.

b. An automatic multielement-indexing X-ray spectrograph.

autunite
 * a. A tetragonal mineral, 2[Ca(UO (sub 2) ) (sub 2) (PO (sub 4) ) (sub 2) .10-12H (sub 2) O] ; radioactive; yellow to pale green; fluorescent; forms scaly or foliated aggregates; results from oxidation or hydrothermal alteration of uranium minerals; an ore of uranium. Syn: calcouranite.

b. The mineral group autunite, fritzscheite, heinrichite, kahlerite, novacekite, sabugalite, saleeite, sodium autunite, torbernite, troegerite, uranocircite, uranospinite, and zeunerite.

auxiliary
 * a. Tools or other equipment, such as a pump, drill rods, casing, core barrel, bits, water swivel, safety clamp, etc., required for use with a drill machine to carry on specific drilling operations.

b. A helper or standby engine or unit. CF: accessory.

auxiliary anode
 * A supplementary anode placed in a position to raise the current density on a certain area of the cathode to get better plate distribution.

auxiliary cylinder
 * A cylinder, operated by compressed air, that is used to assist the main engine of a compressed-air shaker conveyor, esp. where the conveyor cannot develop a sufficient amount of forward acceleration because of grades. The auxiliary cylinder is attached to the conveyor by a driving chain and to a prop by a fixing chain.

auxiliary fault
 * A branch fault. A minor fault ending against a major fault.

auxiliary mineral
 * In Johannsen's classification of igneous rocks, any light-colored, relatively rare mineral, or mineral occurring in small quantities, such as apatite, muscovite, corundum, fluorite, and topaz.

auxiliary operations
 * In metallurgy, diverse operations, such as storing in bins, conveying (by conveyors, feeders, elevators, or pumps), sampling, weighing, reagent feeding, and pulp distribution.

auxiliary ventilation
 * A method of supplementing the main ventilating current in a mine by using a small fan to draw air from the main current and force it through canvas or metal pipe to some particular place, such as the ends of drifts, crosscuts, raises, entries, or other workings driven in a mine. See also: air mover; exhaust ventilation; ventilation tubing; forced auxiliary ventilation; overlap auxiliary ventilation; piped air; reversible auxiliary ventilation; two-fan auxiliary ventilation.