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

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a. A naturally occurring alloy of silver with mercury; mercurian silver. It is found in the oxidation zone of silver deposits and as scattered grains in cinnabar ores. Syn: argental mercury. CF: goldamalgam.

b. A general term for alloys of mercury with one or more of the well-known metals (except iron and platinum); esp. an alloy of mercury with gold, containing 40% to 60% gold, and obtained from the plates in a mill treating gold ore.


a. To unite (a metal) alloy with mercury.

b. To form an amalgam with; as, mercury amalgamates gold.

amalgamated claims

Eng. Mining claims adjoining one another that have been grouped into one claim for more economical working.

amalgamating barrel

A short, cylindrical vessel or barrel, with solid ends turned to fit bearings, used for amalgamating battery accumulations and other material. See also: amalgamator.

amalgamating table

A sloping wooden table covered with a copper plate on which the mercury is spread in order to amalgamate with the precious metal particles.


a. The production of an amalgam or alloy of mercury.

b. The process by which mercury is alloyed with some other metal to produce an amalgam. It was used at one time for the extraction of gold and silver from pulverized ores, but has been superseded by the cyanide process.

amalgamation process

A process of gold or silver recovery in which the ore, finely divided and suspended in water, is passed over a surface of liquid mercury to form an amalgam that is subjected to fire-refining processes for the recovery of the gold or silver. Syn: amalgam treatment.


An apparatus used in mining for bringing pulverized ore into close contact with mercury to extract free metal from it by amalgamation. See also: amalgamating barrel.

amalgam barrel

A small, cylindrical batching mill used to grind auriferous concentrates gently with mercury.

amalgam pan

A muller mill with a horizontal rotating disk bearing on a fixed plate. Gold-bearing material and mercury flow pulpwise between them.

amalgam plate

A sheet of metal with an adherent film of mercury that seizes gold from flowing pulp.

amalgam retort

The vessel where mercury is distilled from gold or silver amalgam.

amalgam treatment

See: amalgamation process.


A term used in Malaysia for the heavy iron and tungsten minerals (and associated minerals) found with placer cassiterite deposits.


A triclinic mineral, Fe(SO (sub 4) )(OH).3H (sub 2) O .


The trade name for a bentonite from the Amargosa River, CA. Syn: montmorillonite. Also called natural soap and soaprock.


a. See: variscite.

b. A green gem cut from variscite and its surrounding matrix of gray, reddish, or brownish crystalline quartz or chalcedony.


See: trass.


A bright, apple- or blue-green variety of microcline; may be carved for art objects. Syn: amazonstone.


See: amazonite.


a. A mineraloid; amorphous hydrocarbons from resins secreted by trees or shrubs upon injury, derived by oxidation and polymerization of nonvolatile terpenoids; in sedimentary rocks and on beaches, e.g., Baltic Sea. See also: chemawinite.

b. A hard, brittle fossil resin, yellow to brown, that takes a fine polish; may contain fossil insects and plant matter. Syn: succinite; bernstein; electrum. See also: resin. c. A group of fossil resins containing considerable succinic acid and having highly variable C:H:O ratios; e.g., almashite, simetite, delatynite, and ambrosine. See also: copal.


A local trade name for a yellowish-green variety of chalcedony from Death Valley, CA.


Former spelling of amber.

amber mica

See: phlogopite.


A gem material consisting of small fragments of genuine amber artificially united or reconstructed by heat and pressure; may be characterized by an obvious flow structure or a dull spot left by a drop of ether. Also spelled ambroid. Syn: pressed amber.

amber opal

A brownish-yellow variety of opal stained by iron oxide.


a. The environment surrounding a body but undisturbed or unaffected by it.

b. Encompassing on all sides; thus, ambient air is the air surrounding.


A yellowish to clove-brown amber found in the phosphate beds near Charleston, SC; it may be a modern resin that has been subjected to the action of salt water. Rich in succinic acids.


Characteristic reactions of minerals to basic methods of mineral processing, studied in preliminary testwork on unknown ores.


Permissible explosive used in coal mines.

American-Belgian furnace

A direct-fired Belgian furnace used in the United States, conforming essentially to the Liege design.

American forge

See: Champlain forge.

American jade

a. Nephrite in Wyoming.

b. See: californite.

American ruby

A red pyrope garnet in Arizona and New Mexico.

American system

See: churn drill.

American Table of Distances

The quantity-distance table, prepared and approved by the Institute of Makers of Explosives (IME), for storage of explosive materials to determine safe distances from inhabited buildings, public highways, passenger railways, and other stored explosive materials.


An apple-green silicate mineral belonging to the phyllosilicate group and occurring in foliated hexagonal plates. See also: magnesium kaolinite.


a. A transparent to translucent, purple to pale-violet variety of quartz common as a semiprecious gemstone. The color results from a hole defect associated with ferric iron substitution for silicon. Syn: bishop's stone.

b. A term applied to a deep-purple variety of corundum and to a pale reddish-violet variety of beryl.


A color designation meaning violet to purplish, used as in amethystine glass and amethystine sapphire.

amethystine quartz

A phenocrystalline variety of quartz colored purplish or bluish violet by manganese. See also: lavendine.

amethyst point

Amethyst crystal, from a geode, commonly possessing only the six (or possibly three) rhombohedral terminal faces; generally with gradational color, the best at the apex commonly grading to colorless at its base.


See: asbestos.


Syn: asbestos. Applied esp. to a fine silky variety such as chrysotile. Also spelled amiantus.


a. Having the appearance of asbestos.

b. An olive-green, coarse, fibrous variety of asbestos.


A stick, tied to the end of a rope, on which workers sit when being raised or lowered in shafts.


A tetragonal mineral, Ca (sub 2) (Be,Al)Si (sub 2) O (sub 7) (OH).H (sub 2) O ; in colorless crystals in Sweden.


One of a group of complex compounds formed by coordination of ammonia molecules with metal ions.


A red or scarlet earthy substance, probably a mixture of copper antimonate and cinnabar; said to occur in some Chilean ore deposits.


A 17th and 18th century term for a sedimentary rock now called oolite. Obsolete syn: ammonite.


An explosive used mainly for heavy quarry blasts in dry boreholes. It consists of TNT, ammonium nitrate, and powdered aluminum.


A colorless, gaseous alkaline compound; NH (sub 3) ; lighter than air; pungent smell and taste. Byproduct of gas and coke production. Used in making fertilizers and explosives.

ammonia dynamite

Dynamite in which part of the nitroglycerin is replaced by ammonium nitrate; used in mining. See also: extra dynamite.

ammonia gelatin

An explosive of the gelatin-dynamite class containing ammonium nitrate.

ammonia gelatin dynamite

See: gelatin dynamite.

ammonia niter

Ammonium nitrate, NH (sub 4) NO (sub 3) ; nitrammite. Also spelled ammonia nitre.

ammonia stillman

In the coke products industry, one who extracts ammonia from liquor for use in producing ammonium sulfate by circulating substances through stills and auxiliary equipment. Also called pump-and-still operator; byproducts stillman.


A trigonal mineral, (NH (sub 4) )Fe (sub 3) (SO (sub 4) ) (sub 2) (OH) (sub 6) ; alunite group. It occurs in pale yellow lumps of tabular grains on the west side of the Kaibab fault, southern Utah.

ammonium chloride

NH (sub 4) Cl ; isometric; and colorless. When dissolved in water, it is used as an electrolyte for some primary cells. Obtained as a byproduct in gas manufacture. Used as a flux in soldering. Also called sal ammoniac.

ammonium hydroxide

A solution of ammonia in water, NH (sub 4) OH .

ammonium nitrate

Used in explosives and as a fertilizer. NH (sub 4) NO (sub 3) ; mol wt, 80.04; colorless.

ammonium nitrate gelignites

These explosives are similar to the straight gelatins except that the main constituent is ammonium nitrate instead of sodium nitrate. Ammonium nitrate is a more active explosive ingredient than sodium nitrate; therefore it can be substituted for nitroglycerin in much larger quantities and still give explosives of high weight strength. The nitroglycerin content is usually 25% to 35%, and the ammonium nitrate content ranges from about 30% to 60%. Ammonium nitrate gelignites are characterized by plastic consistency; high densities of 1.5 to 1.6 g/cm (super 3) ; medium velocity of detonation of 2,500 m/s; and good fume properties. The ammonium nitrate gelignites are useful all-purpose explosives and are widely used in metal mines, nongassy coal mines, quarries, tunneling, and construction work. Its wide range of strengths enables a suitable grade to be selected for blasting almost every variety of rock from hard to soft.


A former named for gersdorffite.


a. Said of a mineral or other substance that lacks crystalline structure, or whose internal arrangement is so irregular that there is no characteristic external form. Ant. crystalline.

b. The state of a solid lacking crystal structure, specif. lacking long-range order. c. A term formerly used to describe a body of rock occurring in a continuous mass, without division into parts. CF: massive.

amorphous coal

A somewhat inaccurate term for a coal in which distinct plant material is not discernible.

amorphous graphite

Very fine-grained, generally sooty graphite from metamorphosed coalbeds. The word amorphous is a misnomer because all graphite is crystalline. The term has also been applied to very fine particles of flake graphite that can be sold only for low-value uses (such as foundry facings), and to fine-grained varieties of Ceylon lump graphite.

amorphous metal

Metal in which the regular arrangement of atoms characteristic of the crystalline state has been destroyed.

amorphous mineral

A mineral with no definite crystalline structure.

amorphous peat

A type of peat in which the original structure of the plants has been destroyed as the result of decomposition of the cellulose matter. It is heavy, compact, and plastic when wet. See also: fibrous peat.

amorphous phosphorus

See: phosphorus.


a. A monoclinic mineral in the cummingtonite-grunerite series.

b. A commercial asbestos composed of asbestiform gedrite, grunerite, or anthophyllite of the amphibole group; has typically long fibers.


A former name for samarskite.


An obsolete term for a black carbonaceous or bituminous shale.


An ancient name applied to a variety of bituminous earth used as an insecticide sprinkled over vines.


The practical unit of electric current. The current produced by 1 V acting through a resistance of 1 Omega .


The quantity of electricity carried past any point of a circuit in 1 h by a steady current of 1 A; 1 A.h equals 3,600 C.

ampere volt

A watt.


A mineral group; characterized by double chains of silica tetrahedra having the composition A (sub 0-1) B (sub 2) Y (sub 5) Z (sub 8) O (sub 22) (OH,F,Cl) , where (A=Ca,Na,K,Pb,B), (B=Ca,Fe,Li,Mg,Mn,Na), (Y=Al,Cr,Fe,Mg,Mn,Ti), and (Z=Al,Be,Si,Ti); in the orthorhombic or monoclinic crystal systems, including actinolite, anthophyllite, arfvedsonite, cummingtonite, hornblende, richterite, glaucophane, grunerite, anthophyllite, riebeckite, tremolite, and others. All display a diagnostic prismatic cleavage in two directions parallel to crystal faces and intersecting at angles of about 54 degrees and 124 degrees . Some members may be asbestiform. See also: pyroxene.

amphibole-magnetite rock

A granular, more or less banded rock containing grunerite, other ferruginous silicates, and magnetite; produced by metamorphism of ferruginous cherts, such as taconite and jaspillite.


A general term, for use in the field, to designate any coarse-grained, holocrystalline igneous rock almost entirely composed of amphibole minerals. Syn: amphibololite.


A crystalloblastic rock consisting mainly of amphibole and plagioclase with little or no quartz. As the content of quartz increases, the rock grades into hornblende plagioclase gneiss. CF: feather amphibolite.

amphibolite facies

The set of metamorphic mineral assemblages (facies) in which basic rocks are represented by hornblende + plagioclase, the plagioclase being oligoclase-andesine or some more calcic variety. Epidote and almandine are common in amphibolites. The facies is typical of regional dynamothermal metamorphism under moderate to high pressures (in excess of 300 MPa) with temperatures in the range 450 to 700 degrees C.


See: amphibolide.


See: leucite.


Having both acidic and basic properties.


See: amygdule.


An extrusive or intrusive rock containing numerous amygdules. Said of a rock having numerous amygdules. Syn: amygdaloidal; mandelstone. See also: amygdule.


a. Said of rocks containing amygdules and of the structure of such rocks; e.g., certain basaltic lava sheets on Keweenaw Point, Lake Superior, which have amygdules filled with native copper, and are important sources of the metal. Syn: amygdaloid; amygdule.

b. Almond-shaped.

amygdaloidal rock

A rock containing amygdules, or the structure of a rock resulting from its presence.


A gas cavity or vesicle, in an igneous rock, that is filled with such secondary minerals as calcite, quartz, chalcedony, or a zeolite. The term amygdale is preferred in British usage. Syn: amygdaloidal. See also: amygdaloid.

amyl alcohol

C (sub 5) H (sub 11) OH ; a frothing agent.

amyl xanthate

A powerful collector agent used in the flotation process.

Anaconda method

A bunch-blasting method in which 6 to 15 fuses, cut to respective lengths 2 in (5.1 cm) longer than required, are tied together near one end by two ravelings of fuse spaced about 5 to 6 in (12.7 to 15.2 cm) apart. A special cutter cuts the fuses off evenly between the two ties, leaving the fuses tied together and offering a smooth face of cut ends. Another bunch is made from the fuses of the remaining holes in the round. By using a short notched fuse as a spitter, the flame is directed against the cut end of one bunch of fuses. As soon as this bunch ignites, it is held close to the face of the second bunch, moving slowly to contact all fuses with the flame from the first bunch. Bunches should be held at least 6 in back from the end to avoid burning the hands. By this method, all the holes of a round are fired in only two groups and by one spitter.


a. Said of an organism (esp. a bacterium) that can live in the absence of free oxygen; also, said of its activities.--n. anaerobe.

b. Said of conditions that exist only in the absence of free oxygen. CF: aerobic.


An isometric mineral, 16[Na(H (sub 2) O)(AlSi (sub 2) O (sub 6) )] ; zeolite group; in white to slightly tinted radiating aggregates or granular masses; a late primary or hydrothermal mineral in mafic igneous rocks, an alkaline lake precipitate, and in silicic tuffs and tuffaceous sandstones. Formerly called analcite.


An extrusive or hypabyssal igneous rock consisting mainly of analcime and pyroxene (usually titanaugite). Feldspathoids, plagioclase, and/or olivine may be present. Apatite, sphene, and opaque oxides may be present as accessories.


Replacement of feldspars or feldspathoids by analcime, usually in igneous rocks during late magmatic or postmagmatic stages. Syn: analcitization.


See: analcimization.

analog computer

A computer that operates with numbers represented by directly measurable quantities (such as length, voltage, or resistance) in a one-to-one correspondence; a measuring device that operates on continuous variables represented by physical or mathematical analogies between the computer variables and the variables of a given problem to be solved.


a. Corresponding to or resembling something else in some way, as in form, proportion, etc.

b. Designating that pole (end) of a pyroelectric crystal to which heating gives a positive charge. CF: antilogous.

analytical chemistry

Study of the qualitative or quantitative composition of materials.

analytic group

A rock-statigraphic unit formerly classed as a formation but now called a group because subdivisions of the unit are considered to be formations.


The part of a polariscope that receives the light after polarization and exhibits its properties. In a petrographic microscope, it is the polarizing mechanism (Nicol prism, Polaroid, etc.) that intersects the light after it has passed through the object under study. See also: polarizer.


High-temperature, high-pressure remelting of preexisting rock to form migma. CF: anatexis.

anamorphic zone

The zone deep in the Earth's crust in which rock flowage takes place. The term, originated in 1898 by Van Hise, is now little used. CF: anamorphism.


Intense metamorphism in the anamorphic zone in which rock flowage takes place and simple minerals of low density are changed into more complex ones of greater density by silication, decarbonization, dehydration, and deoxidation. The term was originated by Van Hise in 1904. CF: anamorphic zone; katamorphism.


a. Pertaining to a network of branching and rejoining fault or vein surfaces or surface traces.

b. Said of the channel pattern of a braided stream.


A tetragonal mineral, 4[TiO (sub 2) ] ; trimorphous with rutile and brookite; brown, greenish-gray, or black; in hydrothermal veins around granite pegmatites, as an alteration of titanium minerals, and as detrital grains. Formerly called octahedrite. See also: octahedrite; titanium dioxide; xanthitane.


See: anatexis.


Melting of preexisting rock. This term is commonly modified by terms such as intergranular, partial, differential, selective, or complete. Adj. anatectic. CF: palingenesis; syntexis; anamigmatization.


A clay mineral near kaolinite, but containing excess silica, probably as interlayered sheets. Monoclinic.


A rapid plow for use on longwall faces. It is suitable for seams from 2 to 8 ft (0.6 to 3.9 m) thick, with reasonably good roof and floor. The plow travels along the face at a speed of 75 ft/min (22.9 m/min) with a cutting depth from 1-1/2 to 3 in (3.8 to 7.6 cm); the broken coal is loaded by the plow-shaped body onto an armored conveyor. The machine can be operated independently of the face conveyor. See also: plow-type machine; Rehisshakenhobel.


Fillings of old workings in a mine, and said to carry gold of recent deposition. This is a product that deposits in most of the old stopes throughout the mine. In some instances, the whole stope for 20 ft (6.1 m) wide is filled. It is apparently siliceous material with more or less pyrite.


That portion of any beam or structure designed to resist pulling out or slipping of the beam or structure when subjected to stress.

anchor bolt

a. A bolt with the threaded portion projecting from a structure, generally used to hold the frame of a building secure against wind load or a machine against the forces of vibration. Also called holding-down bolt; foundation bolt.

b. A bolt or other device used to secure a diamond-drill base to a solid foundation. It may or may not be threaded. c. A lag screw used to anchor the drill base to a platform or sill.

anchor charge

Means of fastening an explosive charge in a seismic shot hole to allow several charges to be preloaded. At each stage the bottom charges are fired first, the upper charges being held down by anchors.

anchor jack

See: jack.

anchor prop

See: stell prop.


A mineral, SrCe(CO (sub 3) ) (sub 2) (OH).H (sub 2) O ; in pegmatites.


An orthorhombic mineral, Al (sub 2) SiO (sub 5) ; trimorphous with kyanite and sillimanite; Mohs hardness, 7-1/2; in aluminous shales and slates subjected to high-temperature, low-stress metamorphism; transparent green varieties used as gems. Syn: cross-stone.


A trigonal mineral, Na (sub 2) Ca(UO (sub 2) )(CO (sub 3) ) (sub 3) .6H (sub 2) O ; bright yellow-green; secondary.

Anderton shearer loader

A widely used cutter loader in which the ordinary jib of the longwall coal cutter is replaced by a shear drum which cuts a web from 16 to 22 in (40.6 to 55.9 cm) depending on its width. The machine travels on an armored conveyor and requires a prop-free front for working. It shears the coal in one direction and the front coal is loaded by a plow deflector, and then returns along the face (without cutting) and loads the remainder of the broken coal. The ordinary Anderton is suitable for coal seams more than 3 ft 6 in (1.1 m) thick.


A triclinic mineral, (Na,Ca)[(Si,Al)AlSi (sub 2) O (sub 8) ] , NaSi 50 to 70 mol %, CaAl 50 to 30 mol %; of the plagioclase series of the feldspar group with prismatic cleavage; white to gray; a common rock-forming mineral in andesites, differentiated gabbros, some anorthosites, and as detrital grains.


A coarse-grained igneous rock almost entirely composed of andesine. It was named by Turner in 1900. CF: anorthosite. Not recommended usage.


A dark-colored, fine-grained extrusive rock that, when porphyritic, contains phenocrysts composed primarily of zoned sodic plagioclase (esp. andesine) and one or more of the mafic minerals (e.g., biotite, hornblende, pyroxene), with a groundmass composed generally of the same minerals as the phenocrysts, although the plagioclase may be more sodic, and quartz is generally present; the extrusive equivalent of diorite. Andesite grades into latite with increasing alkali feldspar content, and into dacite with more alkali feldspar and quartz. It was named by Buch in 1826 from the Andes Mountains, South America.


An orthorhombic mineral, PbAgSb (sub 3) S (sub 6) . Syn: sundtite.


An isometric mineral, 8[Ca (sub 3) Fe (sub 2) Si (sub 3) O (sub 12) ] ; never pure; garnet group; in yellow, green, red, brown, or black dodecahedral and trapezohedral crystals, or may be massive; in calcareous metasediments and placers. Varieties include topazolite, demantoid, melanite, aplome, and bredbergite.


A direction of coal face roughly halfway between the main (bord) and secondary (end) cleavages; on the cross.

Andreasen pipette

An instrument used in the determination of the particle size of clays by the sedimentation method.

Andrews' elutriator

A device for particle size analysis. It consists of (1) a feed vessel or tube, (2) a large hydraulic classifier, (3) an intermediate classifier, and (4) a graduated measuring vessel.


An orthorhombic mineral, (Cu,Fe)Fe (sub 3) (PO (sub 4) ) (sub 3) (OH) (sub 2) ; in bluish-green globules with radial structure.


Broken off by wind erosion and rounded by wind action.


A continuous record of wind speed and direction given by an anemograph.


A self-recording anemometer giving a continuous trace of the direction and velocity of surface wind. In the Dines tube anemograph, the wind pressure acts upon the opening of a tube arranged as a vane to face in the direction of the wind. Pressure is transmitted through the tube to a float carrying a pen, the height of which indicates the wind velocity.


a. An upturned form of calcite stalactite; its form is supposed to have been caused by air currents.

b. A stalactite with one or more changes in its growth axis. Syn: helictite.


An instrument for measuring air velocity. It consists of a small fan from 3 to 6 in (7.6 to 15.2 cm) in diameter that is rotated by the air current. By simple gearing, the number of revolutions of the fan is recorded on dials. It is held in the mine airway for the exact number of minutes (N), the instrument being moved steadily over the entire area. The difference between the initial and the final readings on the dials, divided by N, gives the velocity of the air in feet per minute. Instruments are available for velocities from near zero to 6,000 ft/min (1.83 km/min), also with extension and remote control handles. See also: vane anemometer; self-timing anemometer.

aneroid barograph

Consists essentially of an aneroid barometer and a revolving drum. The movement of the evacuated spring can is transmitted and magnified through a system of levers so that it is finally traced by means of a stylo on the graph paper attached to the revolving drum. The drum is rotated by clockwork, and can be of either the 24-h or the 7-day type. The graph paper is usually marked off in hourly intervals, so that a complete record of the atmospheric pressure at any instant may be obtained. These barographs are used extensively in mining and in meteorological offices.

aneroid barometer

An instrument for measuring atmospheric pressure, built first by Lucien Vidie in about 1843. Basically, variation in pressure with changes in altitude is determined by the movements of the elastic top of a metallic box from which the air has been partly exhausted. Used generally in measuring altitude.


a. An explosive material consisting of ammonium nitrate and fuel oil.

b. A blasting product, with approx. 94.5% industrial-grade ammonium nitrate and 5.5% No. 2 grade diesel fuel oil for a nearly oxygen-balanced mix; available in bulk form for onsite mixing of the AN and fuel or in 50-lb (23-kg) premixed bags as pourable forms. A heavy ANFO product is comprised of up to 45% to 50% ammonium nitrate emulsion mixed with prilled ANFO to increase the bulk density of ANFO; it has improved strength and provides good water resistance in comparison to ANFO.


A triclinic mineral, Fe (sub 4) (AsO (sub 4) ) (sub 2) O (sub 3) ; brownish-black, encrusted on andesite in northwestern Argentina.

angle beam

A two-limbed beam used for turning angles in shafts, etc.

angle brace

A brace used to prevent mine timbers from riding or leaning; a brace across an interior angle.


Drill holes converge, so that a core is blasted out. This leaves an open or relieved cavity or free face for the following shots, which are timed to ensue with a fractional delay.


a. A bulldozer whose blade can be turned at an angle to the direction of travel.

b. A power-operated machine fitted with a blade, adjustable in height and angle, used for digging and side casting, and for spreading loose excavated material; used at opencast pits and dumping sites. c. A bulldozer with a blade that can be pivoted on a vertical center pin, so as to cast its load to either side. Syn: angling dozer.

angle drilling

See: inclined drilling; inclined borehole.

angle hole

A borehole that is drilled at an angle not perpendicular to the Earth's surface. Syn: incline hole.

angle level

See: alidade.

angle of attack

In mine fan terminology, the angle made by the direction of air approach and the chord of the aerofoil section.

angle of bite

In rolling metals where all the force is transmitted through the rolls, maximum attainable angle between roll radius at the first contact and the roll centers. If the operating angle is less, it is called the contact angle or roll angle.

angle of dip

The angle at which strata or mineral deposits are inclined to the horizontal plane. In most localities, earth movements subsequent to the deposition of the strata have caused them to be inclined or tilted. Syn: dip. See also: apparent dip.

angle of draw

a. In coal mine subsidence, this angle is assumed to bisect the angle between the vertical and the angle of repose of the material and is 20 degrees for flat seams. For dipping seams, the angle of break increases, being 35.8 degrees from the vertical for a 40 degrees dip. The main break occurs over the seam at an angle from the vertical equal to half the dip.

b. The angle between the limit line and the vertical. CF: draw.

angle of external friction

The angle between the abscissa and the tangent of the curve representing the relationship of shearing resistance to normal stress acting between soil and the surface of another material.

angle of extinction

In polarized-light microscopy, the angle between an extinction direction and a crystallographic direction--e.g., crystal face, cleavage plane--of an anisotropic mineral. An extinction angle of 0 degrees is called "parallel extinction," an angle of 45 degrees "symmetrical extinction," other angles "oblique extinction;" of diagnostic value in mineral identification. Syn: extinction angle.

angle of friction

The angle between the perpendicular to a surface and the resultant force acting on a body resting on the surface, at which the body begins to slide.

angle of inclination

The angle of slope from the horizontal.

angle of nip

In a rock-crushing machine, the maximum angle subtended by its approaching jaws or roll surfaces at which a piece of ore of specified size can be gripped. See also: nip.

angle of obliquity

The angle between the direction of the resultant stress or force acting on a given plane and the normal to that plane.

angle of polarization

a. That angle, the tangent of which is the index of refraction of a reflecting substance.

b. The angle of reflection from a plane surface at which light is polarized.

angle of pull

The angle between the vertical and an inclined plane bounding the area affected by the subsidence beyond the vertical. Applied to slides of earth.

angle of reflection

a. The angle that a reflected ray of light, on leaving the exterior or interior surface of an object, such as a transparent stone or crystal, makes with the normal to that surface.

b. An erroneous term for the Bragg angle of X-ray diffraction.

angle of repose

See: angle of rest.

angle of rest

The maximum slope at which a heap of any loose or fragmented solid material will stand without sliding or come to rest when poured or dumped in a pile or on a slope. Syn: angle of repose. See also: natural slope.

angle of shear

The angle between the planes of maximum shear, which is bisected by the axis of greatest compression.

angle of slide

The slope, measured in degrees of deviation from the horizontal, on which loose or fragmented solid materials will start to slide; it is a slightly greater angle than the angle of rest.

angle of swing

The number of degrees through which the dipper or shovel bucket moves horizontally from the filled position to the dumping position.


An orthorhombic mineral, 4[PbSO (sub 4) ] ; sp gr, 6.2 to 6.4; in the supergene parts of lead-ore veins; a minor ore of lead. Formerly called lead vitriol, lead spar.

angle to the right

Horizontal angle measured clockwise from the preceding line to the following one.

angle trough

A short curved section of a shaker conveyor trough inserted in a trough line to change the angle of direction. Up to 15 degrees of turn, the angle trough does not employ any means of support other than connection to adjacent troughs. For a greater degree of turn, a fulcrum jack and a swivel device are employed with the trough section.


Rope will only coil closely on the drum within the distance between the centers of the pulleys. Spread or diagonal coiling will result outside this distance unless the drum is grooved: this is known as outside angling and with a grooved drum may amount to 1� degrees . After the normal line between the pulley and the drum is passed, the coils attempt to get back to this normal line. This produces friction crushing between the coils and a danger of coils mounting one over the other; this is known as inside angling and should be kept below 2 degrees . The amount of angling for a given distance between the pulleys will depend upon the distance between the headgear pulleys and the drum. Grooving the drum reduces the difficulties associated with angling. Syn: outside angling.

angling dozer

See: angledozer.


a. A unit of linear measurement in the centimeter-gram-second system. It equals 10 (super -10) m, 10 (super -8) cm, 10 (super -4) mu m, or 10 (super -1) nm. Such ultramicroscopic distances as the dimensions of atoms, molecules, unit cells, and short wavelengths are expressed in angstroms.

b. Either of two units of wavelength: (1) 10 (super -10) m, called the absolute angstrom; or (2) the wavelength of the red spectrum line of cadmium divided by 6,438.4696, which is called the international angstrom.


Having sharp angles or borders; specif. said of a sedimentary particle showing very little or no evidence of abrasion.

angular cutter

A milling cutter on which the cutting face is at an angle with regard to the axis of the cutter.

angularity test

See: slope test.

angular unconformity

An unconformity in which the older underlying strata dip at a different angle (generally steeper) than the younger overlying strata. See also: disconformity.


Said of those minerals of igneous rocks that are not bounded by their own crystal faces, but have an imperfect form impressed on them by the adjacent minerals during crystallization. CF: euhedral; subhedral. Syn: allotriomorphic; xenomorphic.


a. A compound formed from an acid by removal of water.

b. An oxide of a nonmetallic element or an organic radical, capable of forming an acid by uniting with the elements of water, or of being formed by the abstraction of the water, or of uniting with basic oxides to form salts.


An orthorhombic mineral, CaSO (sub 4) ; massive; primarily in evaporite deposits, hot sulfate volcanic waters, and veins; hydrates to gypsum. Formerly called cube spar.


A sedimentary rock composed chiefly of anhydrite.


Said of a substance, e.g., magma or a mineral, that is completely or essentially without water. An anhydrous mineral contains no water in chemical combination.

anhydrous ammonia

Purified ammonia gas, NH (sub 3) , liquefied by cold and pressure.


See: xenomorphic.

aniline point

An approximate measure of the aromatic content of a mixture of hydrocarbons. It is defined as the lowest temperature at which an oil is completely miscible with an equal volume of aniline.


An orthorhombic mineral, Cu (sub 7) S (sub 4) ; alters to a digenitelike crystal solution upon grinding.


A silver ore consisting of a mixture of sulfides, arsenides, and antimonides, with striking intergrowths and in granular masses; contains nickel and lead. CF: macfarlanite.


a. A negatively charged ion, such as a hydroxide, chloride, or sulfate ion; opposite of cation.

b. An atomic particle with a negative charge; one attracted to the anode. CF: cation.

anion exchange capacity

A measure of the ability of a clay to adsorb or exchange anions; usually expressed in milliequivalents or anions per 100 g of dry clay.

anionic collector

A flotation reagent in which the reactive group is acid in character. In these collectors the hydrocarbon group is in the anion. The most common anionic collectors are fatty acids (carboxylic acids). They occur naturally as complex mixtures in which the hydrocarbon chain is saturated or unsaturated.

anionic current

Negative-ion electrical current.

anionic detergent

A detergent in which the anion (negative ion) is the active part.

anionic flotation

A flotation process employing anionic collectors. Anionic collectors are those in which the negative ion (anion) is the effective part. Opposite of cationic flotation, which employs cationic, or positive, ion collectors.


a. An obsolete syn. for heterogranular.

b. Said of crystals with unequal dimensions, including those with significant flattening, elongation, or both. Ant. isometric. CF: equant; tabular. c. See: heterogranular. d. Said of crystal structures with chemical bond strengths that are directionally unequal; e.g., micas.


a. Having unsymmetrical parts; not isometric; applied to crystals with three unequal axes.

b. Of or relating to a rock of granular texture but having mineral constituents of unequal size. c. A textural term applied to granular rocks in which the grains are of different sizes. Obsolete. The term "seriate" expresses the same texture when the crystals vary gradually or in a continuous series. CF: isodiametric; isometric.


Having physical properties that vary in different directions. Specif. in optical crystallography showing double refraction. Characteristic of all crystalline substances, including minerals, except those belonging in the isometric system, which are isotropic. Opposite of isotropic.

anisotropic fabric

A fabric in which there is preferred orientation of the minerals of which the rock is composed.


a. The property of being anisotropic, or exhibiting properties (such as velocity of light transmission, conductivity of heat or electricity, or compressibility) with different values when measured along axes in different directions.

b. The condition of having different properties in different directions as in geologic strata that transmit sound waves with different velocities in the vertical and in the horizontal directions. c. Optically descriptive of crystalline materials having light velocities and indices of refraction dependent upon the crystallographic direction of the electric vector (vibration direction) during transmission or reflection; it includes all nonisometric crystals. CF: uniaxial; extinction; isotropy. d. In geostatistics, the situation where a variogram exhibits a longer range (i.e., better correlation) in one direction than in another.


A trigonal mineral, Ca(Fe,Mg,Mn)(CO (sub 3) ) (sub 2) ; dolomite group; forms series with dolomite and with kutnohorite; associated with iron ores; commonly forms thin veins in some coal seams. CF: ferroan dolomite; cleat spar. See also: pearl spar.


A monoclinic mineral, 2[Ni (sub 3) (AsO (sub 4) ) (sub 2) .8H (sub 2) O] ; vivianite group with cobalt replacing nickel toward erythrite; occurs as light-green soft coatings of fine striated crystals, or earthy; an oxidation product of nickel and cobalt arsenides, the green crusts being a distinctive guide to nickel ores. Formerly called nickel ocher. CF: nickel bloom.

annealed wire rope

A wire rope made from wires that have been softened by annealing.


a. Heating to and holding at a suitable temperature and then cooling at a suitable rate for such purposes as reducing hardness; improving machinability; facilitating cold working; producing a desired microstructure; or obtaining desired mechanical, physical, or other properties. When applied to ferrous alloys, the term "annealing", without qualification, implies full annealing. When applied to nonferrous alloys, annealing implies a heat treatment designed to soften a cold-worked structure by recrystallization or subsequent grain growth or to soften an age-hardened alloy by causing a nearly complete precipitation of the second phase in relatively coarse form.

b. The variation of the cooling rate at different temperatures of porcelain, glass, and other ceramic ware containing large quantities of vitreous material to prevent defects such as dunting, crazing, cracking, crystallization, etc. c. The process by which glass and certain metals are heated and then slowly cooled to make them more tenacious and less brittle. Important in connection with the manufacture of steel castings, forgings, etc. d. The process of heating metal shapes to a red heat or above, prior to cleaning.

annealing color

The hue taken by steel in annealing.

annealing oven

A oven for heating and gradually cooling metals or glass to render them less brittle. Also called annealing furnace.


A black mixture of samarskite with parallel overgrowths of columbite. Also spelled aanerodite.


A monoclinic mineral, KFe (sub 3) AlSi (sub 3) O (sub 10) (OH,F) (sub 2) ; mica group; trioctahedral.


A variety of tennantite with arsenic partly replaced by bismuth and antimony.

annual labor

Same as assessment work, on mining claims.

annual layer

a. A sedimentary layer deposited or presumed to have been deposited during the course of a year; e.g., a glacial varve.

b. A dark band (in a salt stock) of formerly disseminated anhydrite crystals that accumulated upon being freed by solution of the enclosing salt.

annual value

The annual value of a property is the estimated annual surplus of revenue over expenditure in process of liquidating the mineral reserves. In the usual case, that of a property owned by a company, it is the dividend estimated maintainable annually over the whole computed life, the regular distribution of mining profit.

annular bearing

A ring bearing that carries the radial load of a shaft. If a ball bearing, the balls are held in a race and run on a hard band around the shaft.

annular-drainage pattern

A drainage pattern in which streams follow a roughly circular or concentric path along a belt of weak rock, resembling in plan a ringlike pattern. It is best displayed by streams draining a maturely dissected structural dome or basin where erosion has exposed rimming sedimentary strata of greatly varying degrees of hardness, as in the Red Valley, which nearly encircles the domal structure of the Black Hills, SD.

annular kiln

A kiln having compartments.


a. The positive pole of an electrolytic cell.

b. The terminal at which current enters a primary cell or storage battery; it is positive with respect to the device and negative with respect to the external circuit. c. The electropositive pole. d. The electrode at which electrons leave a device to enter the external circuit; opposite of cathode. See also: electrode. e. The negative terminal of a primary cell or of a storage battery that is delivering current.

anode compartment

In an electrolytic cell, the enclosure formed by a diaphragm around the anodes.

anode copper

Specially shaped copper slabs used as anodes in electrolytic refinement, and resulting from the refinement of blister copper in a reverberatory furnace.

anode effect

The effect produced by polarization of an anode in the electrolysis of fused salts. It is characterized by a sudden increase in voltage and a corresponding decrease in amperage due to the anode being virtually separated from the electrolyte by a gas film.

anode furnace

A copper- or nickel-refining furnace, in which blister copper or impure nickel is refined.

anode metals

Metals used for electroplating. They are as pure as commercially possible, uniform in texture and composition, and have the skin removed by machining. In addition to pure single metals, various alloys are produced in anode form, such as Platers' brass and Spekwite, the latter yielding a white plate harder than nickel.

anode mud

A deposit of insoluble residue formed from the dissolution of the anode in commercial electrolysis. Sometimes called anode slime. In copper refining, this slime contains the precious metals that are recovered from it.

anode scrap

Remnants of anode copper retrieved from electrolytic refining of the metal.

anode slime

Metals or metal compounds left at, or falling from, the anode during electrolytic refining. The plural form is often used.

anodic zone

In the electrical self-potential method of geophysical prospecting, if the chemical composition of the soil or subsoil is such as to give electrical polarization, the zone of electropositive potential is the anodic zone.


a. A departure from the expected or normal.

b. The difference between an observed value and the corresponding computed value. c. A geological feature, esp. in the subsurface, distinguished by geological, geophysical, or geochemical means, which is different from the general surroundings and is often of potential economic value; e.g., a magnetic anomaly. d. Any deviation from conformity or regularity. A distinctive local feature in a geophysical, geological, or geochemical survey over a larger area. An area or a restricted portion of a geophysical survey, such as a magnetic survey or a gravity survey, that differs from the rest of the survey in general. The anomaly might be associated with petroleum, natural gas, or mineral deposits, or provide a key to interpreting the underlying geologic structure. Drilling for economic mineral deposits might be conducted in the area of a geophysical anomaly. In seismic usage, anomaly is generally synonymous with subsurface structure or material properties, but it is also used for spurious or unexplainable seismic events or for local deviations of observed signals which cannot be conclusively attributed to a unique cause. See also: hydrochemical anomaly. e. A gravity anomaly is the difference between the theoretical calculated gravity and the observed terrestrial gravity. In comparing any set of observed data with a computed theoretical curve, the difference of an observed value and the corresponding computed value, or the observed minus the computed value. Excess observed gravity is a positive anomaly, and a deficiency is a negative anomaly. See also: Bouguer anomaly; free-air anomaly; isostatic anomaly. f. A crystallographic anomaly is the lack of agreement between the apparent external symmetry of a crystal and the observed optical properties. g. Any departure from the normal magnetic field of the Earth is a magnetic anomaly. It may be a high or a low, subcircular, ridgelike or valleylike, or linear and dikelike.


Obsolete syn. for a triclinic crystal system. See also: triclinic.


a. A triclinic mineral, 4[CaAl (sub 2) Si (sub 2) O (sub 8) ] ; plagioclase series of the feldspar group, with up to 10 mol % NaSi replacing CaAl; white to gray; in ultramafic intrusive igneous bodies and skarns. Syn: calcium feldspar; calcium plagioclase; calciclase; lepolite.

b. A pure calcium end member of the plagioclase series.


A triclinic mineral, 4[(Na,K)AlSi (sub 3) O (sub 8) ] ; feldspar group; occurs in tabular crystals with prismatic cleavage; colorless or white; in felsic volcanic rocks. CF: orthoclase.


A plutonic rock composed almost entirely of plagioclase, usually labradorite. It is a monomineralic equivalent of gabbro but lacks monoclinic pyroxene. CF: andesinite.


Introduction of, or replacement by, anorthosite.


Oxygen deficiency in the blood cell or tissues of the body in such degree as to cause psychological and physiological disturbances. Anoxia may result from a scarcity of oxygen in the air being breathed or from an inability of the body tissues to absorb oxygen under conditions of low ambient pressure. Also called hypoxia. Syn: oxygen deficiency.


In blast-hole drilling, the cuttings around the hole collar.


A triclinic mineral, WAlO (sub 3) (OH) (sub 3) ; in tungstic ochers in central Africa and Tasmania.


A monoclinic mineral, Cu(OH,Cl) (sub 2) .3H (sub 2) O ; lavender colored; from the Centennial Mine in Calumet, MI. CF: calumetite.


An orthorhombic mineral, 4[(Mg,Fe) (sub 7) Si (sub 8) O (sub 22) (OH) (sub 2) ] ; amphibole group; commonly lamellar or fibrous, green to clove-brown; in schists from metamorphosed ultramafic rocks; a nonspinning grade of asbestos.


From Greek anthrax, coal; also, a precious stone; combining forms used commonly to denote substances resembling or derived from coal, or fossils found in coal measures.


Obtained by the distillation of coal tar. Used in the manufacture of dyestuffs.

anthracene oil

A heavy green oil that distills from coal tar above 270 degrees C and is the principal source of anthracene, phenanthrene, and carbozole.


a. A hard, black lustrous coal containing a high percentage of fixed carbon and a low percentage of volatile matter. Commonly referred to as hard coal, it is mined in the United States, mainly in eastern Pennsylvania, although in small quantities in other States.

b. The rank of coal, within the anthracitic class of Classification D 388, such that on the dry and mineral-matter-free basis, the volatile matter content of the coal is greater than 2% but equal to or less than 8% (or the fixed carbon content is equal to or greater than 92% but less than 98%), and the coal is nonagglomerating. c. Coal of the highest metamorphic rank, in which fixed-carbon content is between 92% and 98% (on a dry, mineral-matter-free basis). It is hard and black, and has a semimetallic luster and semiconchoidal fracture. Anthracite ignites with difficulty and burns with a short blue flame, without smoke. Syn: hard coal; stone coal; kilkenny coal. See also: solid smokeless fuel.

anthracite-coal-base carbon refractory

A manufactured refractory comprised substantially of calcined anthracite coal.

anthracite coal sizes

The sizes by which anthracite coal is marketed. The sizes are called broken, egg, stove, chestnut, pea, and buckwheat. Size is graded according to the size of round mesh a piece will pass through.

anthracite duff

In Wales, fine screenings used in making pitch-bonded briquets and for mixing with bituminous coal to be burned in cement kilns, on chain grate stokers, and as powdered fuel.

anthracite fines

The product from an anthracite coal-preparation plant, usually below 1/8 in (3.2 mm). See also: duff; fines; grain.

anthracite silt

Minute particles of anthracite too fine to be used in ordinary combustion.


Pertaining to anthracite.


a. The science of coal.

b. Coal petrography, a branch of geology dealing with the physical constitution of coal in much the same way that petrography deals with the mineral composition of rocks. It is concerned with the physical variations in coal that make it possible to classify coal material by type.


An instrument for determining the amount of carbon dioxide in a mixture of gases.


See: bituminous limestone; stinkstone; swinestone.


Massive fibrosis of the lungs marked by shortness of breath from inhalation of carbon and quartz dusts. Also called miner's phthisis. See also: anthracosis.


A deposition of coal dust within the lungs from inhalation of sooty air. Syn: blacklung; collier's lung. CF: anthracosilicosis. See also: mining disease.


Anthracite used for filtration purposes.


Sizes of anthracite smaller than barley.


Variant of anthracosilicosis.


a. A highly graphitic coal. One specimen contained 97.7% fixed carbon.

b. Anthracitelike asphaltic material occurring in veins in Precambrian slate of the Sudbury district, ON, Can. c. Probably fragmentary coalified wood.


The vitreous appearing components of coal, which in thin section are shown to have been derived from the woody tissues of plants--such as stems, limbs, branches, twigs, roots, including both wood and cortex--changed and broken up into fragments of greatly varying sizes through biological decomposition and weathering during the peat stage, and later flattened and transformed into coal through the coalification process, but still present as definite units.

anthraxylous coal

A bright coal (composed of anthraxylon and attritus in which the translucent cell-wall degradation matter or translucent humic matter predominates) in which the ratio of anthraxylon to attritus is from 3:1 to 1:1. CF: attrital coal.

antibreakage device

A cushioning device to reduce the impact of coal in motion against objects with which it may come into contact, with a view to avoiding fracture of the coal.


a. Pertaining to an anticline. CF: synclinal.

b. Inclining in opposite directions. Having or relating to a fold in which the sides dip from a common line or crest. Of or pertaining to an anticline. The opposite of synclinal. c. The crest of an anticlinal roll may be the apex of a vein. d. Said of strata assuming an arch-shaped form.

anticlinal axis

a. The medial line of an upfolded structure, from which the strata dip on either side.

b. If a range of hills or a valley is composed of strata that on the two sides dip in opposite directions, the imaginary line that lies between them and toward which the strata on each side rise is called an anticlinal axis. See also: axis.

anticlinal bend

An upwardly convex flexure in which one limb dips gently toward the apex and the other limb dips more steeply away from it. CF: unicline; monocline.

anticlinal mountain

A mountain whose geologic structure is that of an anticline. CF: synclinal mountain.

anticlinal valley

A valley that follows an anticlinal axis. The term was used as early as 1862 by C.H. Hitchcock. CF: synclinal valley.


a. A fold, generally convex upward, whose core contains the stratigraphically older rocks. Ant. syncline. See also: antiform.

b. Applied to strata that dip in opposite directions from a common ridge or axis, like the roof of a house; the structure is termed an anticline or saddleback. c. In this type of fold (anticline) the sides or limbs of the fold typically slope away from the plane of the axis of either side. Every anticlinal axis pitches in two directions; i.e., toward the two ends of the fold.


A series of anticlines and synclines, so grouped that taken together they have the general outline of an arch; opposite of synclinorium.


Spontaneous magnetic orientation of atoms with equal magnetic moments aligned in opposite directions.


A state where d electrons are ordered in an antiparallel array, giving materials small positive values for magnetic susceptibility and weak attraction to an external magnetic field. CF: ferrimagnetism; ferromagnetism; superexchange.


A fold whose limbs close upward in strata for which the stratigraphic sequence is not known. CF: anticline. Ant. synform.

antifriction bearing

A bearing consisting of an inner and outer ring, separated by balls or rollers held in position by a cage.


A monoclinic mineral, (Mg,Fe) (sub 3) Si (sub 2) O (sub 5) (OH) (sub 4) ; kaolinite-serpentine group; polymorphous with clinochrysotile, lizardite, orthochrysotile, parachrysotile; greasy variegated green; used as an ornamental stone. See also: baltimorite.


Designating the pole (end) of a pyroelectric crystal that is negative while the crystal is being heated and positive as it cools. CF: analogous.


See: transformist.


a. A salt or ester of antimonic acid; a compound containing the radical SbO (sub 4) (super -3) , SbO (sub 3) (super -1) , or Sb (sub 2) O (sub 7) (super -4) (diantimonate) in which antimony has a +5 valence.

b. A salt containing pentavalent antimony and oxygen in the anion. c. A mineral characterized by inclusion of antimony and oxygen; e.g., swedenborgite, NaBe (sub 4) SbO (sub 7) .

antimonial arsenic

A native compound of arsenic and antimony of which the antimony forms a comparatively small part. CF: allemontite.

antimonial copper

See: chalcostibite.

antimonial red silver

See: pyrargyrite.

antimonial silver

a. Silver ore or alloys containing variable quantities of antimony.

b. See: dyscrasite.


a. A salt or ester of antimonious acid or antimonous acid; a compound containing the radical SbO (sub 3) (super -3) or SbO (sub 2) (super -1) in which antimony has a +3 valence.

b. See: stibnite.


A monoclinic mineral, (Ag,Cu) (sub 16) (Sb,As) (sub 2) S (sub 11) . CF: arsenpolybasite.


Metallic antimony is an extremely brittle metal with a flaky, crystalline texture. Symbol, Sb. Sometimes found native, but more frequently as the sulfide, stibnite (Sb (sub 2) S (sub 3) ). Used in semiconductors, batteries, antifriction alloys, type metal, small arms, tracer bullets, cable sheathing, flame-proofing compounds, paints, ceramics, glass, and pottery. Antimony and many of its products are toxic.

antimony blende

See: kermesite.

antimony crudum

The name given to the molten, high-grade sulfide that drains away from the gangue residue when stibnite (antimony sulfide) is melted by liquation.

antimony glance

See: stibnite.

antimony ocher

Any of several native antimony oxides; e.g., stibiconite, cervantite.

antimony regulus

An impure product of the smelting process; largely antimony sulfide.

antimony star

The fernlike marking on the upper surface of the metal antimony when well crystallized.

antimony trioxide

See: valentite.


A point, line, or surface in a standing wave system where some characteristic of the wave field has maximum amplitude. Antinodes, like nodes, may be of several types, such as pressure or velocity.

antipathy of minerals

The incompatibility of certain rock-forming minerals, according to the theory of fractional crystallization, results from their being too far apart in a crystallization sequence to be associated in such quantities as to make up the entire rock. Thus, a rock made up of quartz and calcic plagioclase is unknown among igneous rocks.


An intergrowth of a sodic and a potassic feldspar, generally considered to have formed during slow cooling by the unmixing of sodium and potassium ions in an originally homogeneous alkalic feldspar. In an antiperthite, the potassic member (usually orthoclase) forms thin films, lamellae, strings, or irregular veinlets, within the sodic member (usually albite). CF: perthite.


Descriptive of materials that normally have high insulating qualities, e.g., rubber hoses and belts that have been rendered conductive to reduce risk of sparks or electric shocks in mines, or other places where there is a fire risk.

antistress mineral

A term suggested for minerals such as cordierite, the feldspars, the pyroxenes, forsterite, and andalusite, whose formation in metamorphosed rocks is believed to be favored by conditions that are not controlled by shearing stress, but by thermal action and by hydrostatic pressure that is probably no more than moderate. CF: stress mineral.

antithetic fault

A fault that dips in the opposite direction from the direction in which the associated sediments dip. Opposite of synthetic fault. Syn: antithetic shear.

antithetic shear

See: antithetic fault.

antitropal ventilation

Ventilation by a current of air traveling in the opposite direction to that of the flow of mineral out of the mine. See also: ascensional ventilation; descensional ventilation; homotropal ventilation.

antiturbidity overflow system

A system fitted to a drag suction hopper dredge which disperses entrained gases from the overflow in a settling tank and discharges the degassed overflow below the surface. The resulting plume is normally compact and does not appear at the surface. Abbrev., ATOS.


An orthorhombic mineral, 4[Cu (sub 3) SO (sub 4) (OH) (sub 4) ] ; forms emerald to blackish-green striated crystals or parallel aggregates; may be reniform or massive; in oxidized parts of copper veins; an ore of copper in desert regions. Syn: vernadskite.

AN-TNT slurry

Mixture of ammonium nitrate and trinitrotoluene used as an explosive.


See: eriochalcite.


A dark-violet to black semiopaque variety of fluorite that emits a strong odor when crushed; commonly causing nausea among miners, perhaps owing to free fluorine; produced by alpha bombardment, as in the inner bands of halos surrounding uraninite and thorite inclusions.


a. The stationary serrated jaw piece or plate of a safety clamp, adjustable pipe wrench, or jaw-type rock crusher. Also sometimes incorrectly used as a syn. for drive hammer. Also called anvil block; anvil heel; anvil jaw; heel.

b. An iron block placed between a stamp-mill mortar box and the foundation block; generally used in light mortars and concrete foundations. c. In drop forging, the base of the hammer into which the sow block and lower die part are set. d. A block of steel upon which metal is forged.

anvil block

A massive block of cast iron placed beneath the anvils of steam and other heavy hammers to absorb vibration. It is often embedded in masonry or concrete.

anvil jaw

See: anvil.

anvil stone

Eng. Blue building stone, forming a bed of irregular anvil-shaped blocks.

anvil vise

A vise with an anvil on one jaw.


See: zincite.


A hydrous ferric sulfate, found in yellow nodules in clay.


a. Any hexagonal or monoclinic pseudohexagonal mineral with the general formula A (sub 5) (XO (sub 4) ) (sub 3) (F,Cl,OH) , where A = (Ba,Ca,Ce,K,Na,Pb,Sr,Y) and X = (As,C,P,Si,V). Syn: calcium phosphate.

b. A mineral group fluorapatite, chlorapatite, hydroxylapatite, carbonate-fluorapatite (francolite), and carbonate-hydroxylapatite (dahllite).


a. The highest point of a vein relative to the surface, whether it crops out or not. The concept is used in mining law. See also: apex law.

b. The tip, summit, or highest point of a landform, as of a mountain; specif. the highest point on an alluvial fan, usually the point where the stream that formed the fan emerged from the mountain or from confining canyon walls. Syn: culmination. c. The highest point of a stratum, as a coalbed. d. The top of an anticlinal fold of strata. e. In U.S. mining law, used to designate the highest limit of a vein. f. The top of an inclined haulage plane. See also: brow; landing. g. Point in the center of the face of a concave, noncoring bit. h. In a classifier or hydrocyclone, the underflow aperture through which the coarser and heavier fraction of the solids in a pulp is discharged in accordance with its minimum cross section.

apex law

a. This law gives the owner of a properly located claim on a vein the right to an indefinite extension on the dip of the vein beyond the vertical planes through the side lines of the claim. In order to secure this right, the owner must lay out the end lines of the claim parallel and of substantial length. A triangular claim would have no apex right and cannot be patented.

b. Obsolescent mining law allowing the owner of a lode to follow it in depth, regardless of the vertical extension of the legal surface boundaries. c. In U.S. mining law, the individual whose claim contains the apex of a vein may follow and exploit the vein indefinitely along its dip, even if it passes downdip under adjoining surface property lines. Syn: law of extralateral rights. See also: apex.


See: clinoclase.


Any fine-grained igneous rock whose components are not distinguishable with the unaided eye; a rock having aphanitic texture. CF: aphanitic. Syn: cryptomere; felsite; felsitoid.


a. Said of the texture of an igneous rock in which the crystalline components are not distinguishable by the unaided eye; also said of a rock or a groundmass exhibiting such texture. CF: aphanite; phaneritic. Syn: fine-grained.

b. A crystalline texture with individual crystals too small to be visible to the unaided eye. Syn: cryptocrystalline.


A porphyritic igneous rock having a groundmass which the unaided eye cannot distniguish as either crystalline or noncrystalline.


A steel-gray argentiferous variety of tetrahedrite.


A foliated or scaly white pearly variety of calcite. Syn: earth foam; foam spar.


See: stevensite.


Said of the texture of a fine-grained or aphanitic igneous rock that lacks phenocrysts. Also, said of a rock exhibiting such texture.

aplanachromatic lens

A lens free from both chromatic aberration and spherical aberration. See also: achromatic. CF: aplanatic lens; aberration; achromatic.

aplanatic lens

A lens free from spherical aberration. CF: aberration. See also: aplanachromatic lens.


A light-colored igneous rock characterized by a fine-grained saccharoidal (i.e., aplitic) texture. Aplites may range in composition from granitic to gabbroic, but the term aplite with no modifier is generally understood to mean granitic aplite, consisting essentially of quartz, potassium feldspar, and acid plagioclase. The term, from a Greek word meaning simple, was in use before 1823. Syn: haplite. The rock has been used in glass manufacture.


a. Pertaining to the fine-grained and saccharoidal texture characteristic of aplites.

b. Said of an igneous rock having such a texture.


A light-colored rock of granitic texture consisting essentially of alkali feldspar and quartz, with subordinate biotite; muscovite may be present or absent. CF: two-mica granite; alaskite.


A nongelatinous permissible explosive. Used in coal mining.

Apold-Fleissner process

A method of roasting carbonate iron ore in a shaft furnace. The ore sinks continuously down the furnace while a current of hot air or flue gas, with a low carbon dioxide content, is passed through the body of the ore and a current of cold air is passed upward through the lower part of the shaft, this part acting as a cooling chamber for the ore and as a preheating flue for the air, which rapidly oxidizes the ferrous oxide in the upper regions of the furnace. The quantity and temperature of the hot gases and cold air are carefully regulated, so as to keep the carbon dioxide content of the flue gas at a minimum and thereby ensure thorough roasting of the ore at the lowest possible temperature. A furnace roasting 181 to 408 t/d requires about 176,400 to 220,500 (736 to 923 kg.kJ/t), giving a heat efficiency of 73%.


Said of a hydrothermal mineral deposit at an intermediate distance from its magmatic source. The term is little used. CF: telemagmatic; cryptomagmatic.


A mineral group, 2[KFCa (sub 4) (Si (sub 8) O (sub 20) ).8H (sub 2) O] (fluorapophyllite) with F replaced by (OH) (hydroxyapophyllite) and K replaced by Na (natroapophyllite); occurs in square micaceous crystals as secondary minerals in cavities in igneous rocks. Syn: fisheye stone.


See: tongue.


A rhyolite, the groundmass of which was once glassy but has become devitrified.

Appalachian coalfield

The coal-producing area extending from northern Pennsylvania to Alabama, in and adjacent to the Appalachian Mountains.

Appalachian orogeny

a. Late Paleozoic Era diastrophism beginning perhaps in the Late Devonian Period and continuing until the end of the Permian Period.

b. A period of intense mountain-building movements in the late Paleozoic Era, during which the deposits in the Appalachian and Cordilleran geosynclines were folded to form the Appalachian and Palaeocordilleran mountains. Equivalent to the Armorican and Hercynian movements in Europe. Syn: Appalachian revolution.

Appalachian revolution

See: Appalachian orogeny.

apparent cohesion

a. In soil mechanics, the resistance of particles to being pulled apart, due to the surface tension of the moisture film surrounding each particle. Also called moisture film cohesion.

b. Cohesion in granular soils due to capillary forces. See also: cohesion.

apparent density

a. The weight (W) of an object or material divided by its exterior volume (V (sub e) ) less the volume of its open pores (V (sub p) ). Apparent density = W/(V (sub e) - V (sub p) ).

b. Weight per apparent volume. See also: density. CF: bulk density.

apparent dip

The dip of a rock layer as measured in any exposed section, or direction, not at a right angle to the strike. It is a component of, and hence always less than, the true dip. See also: angle of dip; true dip; dip.

apparent movement of a fault

The apparent movement observed in any chance section across a fault is a function of several variables: the attitude of the fault; the attitude of the disrupted strata; the attitude of the surface upon which the fault is observed; and the true movement (net slip) along the fault.

apparent plunge

The inclination of a normal projection of lineation in the plane of a vertical cross section. CF: plunge.

apparent porosity

The ratio of the volume of open pore space in a specimen to the exterior volume.

apparent resistivity

The measured electrical resistivity between two points on the Earth's surface, which corresponds to the sensitivity the ground would have if it were homogeneous.

apparent specific gravity

a. Specific gravity of a rock as measured by water displacement, taking into account the effect of sealed pore spaces as well as constituent minerals. See also: specific gravity.

b. The ratio of the weight in air of a given volume of the impermeable portion of a permeable material (e.g., the solid matter including its impermeable pores or voids) at a stated temperature to the weight in air of an equal volume of distilled water at a stated temperature. c. This property is determined by the standard method of dividing the weight of a rock by the weight of an equal volume of water. The term apparent specific gravity is used because water cannot penetrate the closed pore spaces inside the rock, and hence the specific gravity measured by water displacement methods includes the effect of internal pore spaces as well as that of the constituent minerals.

apparent superposition

The actual or visible order in which strata lie in any locality.

apparent velocity

The velocity with which a seismic-signal wavefront appears to travel along the surface of the Earth. It exceeds the actual velocity if the wave train is not traveling parallel to the surface.

apparent volume

True volume plus closed-pore volume.

apparent width

The width of a vein or other tabular formation as determined by borehole intercepts. This width will always be greater than the true width if the borehole intersects the vein at any direction other than perpendicular to the surface of the vein. CF: true width.

appliances of transportation

As applied to a coal mine, these include parts of the locomotive, mobile conveyor, and elevator transportation systems for the removal of coal.

Appolt oven

An oven for the manufacture of coke, differing from the Belgian oven in that it is divided into vertical compartments.


The estimation or fixing of a money value on anything, such as a gemstone. Differs from valuation and evaluation.

approach distance

The linear distance, in the direction of feed, between the point of initial cutter contact and the point of full cutter contact.


In the mining law, the posting of notice at or near the point where the ledge is exposed; next, the recording of the notice; next, the marking of the boundaries.

approved permissible flame safety lamp

A flame safety lamp that has been approved for use in gaseous coal mines.

approximate original contour

The surface configuration achieved by backfilling and grading of the mined area so that the reclaimed area, including any terracing or access roads, closely resembles the general surface configuration of the land prior to mining and blends into and complements the drainage pattern of the surrounding terrain, with all highwalls, spoil piles, and coal refuse piles eliminated.


Trade name for yellowish-red, apricot-colored quartz pebbles; may be of gem quality; near Cape May, NJ.


a. A canvas-covered frame set at such an angle in a miner's rocker that the gravel and water in passing over it are carried to the head of the machine.

b. An amalgamated copper plate placed below a stamp battery, over which pulp passes. The free gold contained in the pulp is amalgamated by mercury on the plate. c. A broad shallow vat used for evaporating. d. A receptacle or endless belt for conveying material (such as rock) by means of a cableway and trolley. Syn: traveling apron. e. The front gate of a scraper body. f. See: morainal apron.

apron conveyor

a. A series of overlapping metal plates or aprons running in an endless chain for transferring material from one place to another. Often used to feed raw material from a bin.

b. A conveyor so contrived as to provide a moving platform on which materials can be carried. Syn: hinged apron.

apron feed

A method of feeding material forward on an articulated platform.

apron feeder

A feeder in which the material is carried on an apron conveyor and in which the rate of feed is adjusted either by varying the depth of material or the speed of the conveyor, or both. See also: conveyor-type feeder. Also called plate-belt feeder; plate feeder.

apron plate

Sheet of copper or special alloy set in front of a stamp battery and coated with mercury to trap and amalgamate gold.

apron rope

The operating rope for the blade front of a scraper.

apron wall

That part of a panel wall between the windowsill and the support of the panel wall.


a. Not changed by extreme heat, e.g., mica; distinguished from refractory.

b. Noncombustible.