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Appendix:Dictionary of Mining, Mineral, and Related Terms/G/1

Ga
 * Billions of years before the present.

gabbro
 * A group of dark-colored, basic intrusive igneous rocks composed principally of basic plagioclase (commonly labradorite or bytownite) and clinopyroxene (augite), with or without olivine and orthopyroxene; also, any member of that group. It is the approximate intrusive equivalent of basalt. Apatite and magnetite or ilmenite are common accessory minerals.

gabbroid
 * Said of a rock resembling gabbro.

gable-bottom car
 * See: mine car.

gabrielsonite
 * An orthorhombic mineral, PbFe(AsO (sub 4) )(OH) ; adelite group; forms black adamantine lumps at Laangban, Sweden.

gad
 * A heavy steel wedge, 6 in or 8 in (15.2 cm or 20.3 cm) long, with a narrow chisel point for cutting samples or breaking out pieces of loose rock.

gadder
 * In quarrying, a small car or platform carrying a drilling machine, so as to make a straight line of holes along its course in getting out dimension stone. Also called gadding car. Syn: gadding machine.

gadding machine
 * See: gadder.

gadolinite
 * a. A monoclinic mineral, (Y,Ce,La,Nd) (sub 2) Be (sub 2) Si (sub 2) O (sub 10) ; further speciated according to the predominant rare-earth element; weakly radioactive; occurs with fluorite, allanite, and beryl in granites and granite pegmatites; with xenotime in biotite gneisses.

b. The mineral group bakerite, datolite, gadolinite-(Ce), gadolinite-(Y), hingganite-(Ce), hingganite-(Y), hingganite-(Yb), homilite, and minasgeraisite-(Y).

gagatite
 * Jetlike coalified plant material preserving cellular structures. See also: gagatization.

gagatization
 * In coal formation, the impregnation of wood fragments with dissolved organic substances. See also: gagatite.

gage
 * a. Spacing of tracks or wheels.

b. The nominal size of an aggregate. It is the minimum size of sieve through which at least 95% of an aggregate will pass. Also spelled gauge.

gage cock
 * A small cock in a boiler at the water line, to determine the water level.

gage door
 * A wooden door fixed in an airway for regulating the supply of ventilation necessary for a certain district or number of workers. Also called a regulator.

gage factor
 * The percentage charge of resistance divided by the percentage strain. For strain gages in common use, this amounts to about 2.2.

gage loss
 * The diametrical reduction in the size of a bit or reaming shell caused by wear through use.

gager
 * In the iron and steel industry, one who determines whether iron or steel bars, sheets, or wire are being rolled to plant specification, so that the rolls may be adjusted to reduce the metal the desired amount for each pass, using calipers to check the thickness (gage) of the various products.

gage size
 * The width of a drill bit along the cutting edge.

gage stone
 * Any one of several diamonds set in the crown of a diamond bit in a plane parallel with and projecting slightly beyond the inside and/or outside walls of the bit. Syn: kicker; kicker stone; reaming diamond. CF: cutting stones.

gaging
 * A heap of rubbish placed at the entrance of a disused roadway underground.

gaging station
 * A particular site on a stream, canal, lake, or reservoir where systematic observations of gage height, discharge, or water quality (or any combination of these) are obtained.

gahnite
 * An isometric mineral, ZnAl (sub 2) O (sub 4) ; spinel group; forms series with spinel and with hercynite; Mohs hardness, 7-1/2; forms octahedra or masses in schists, contact-metamorphosed limestones, granite pegmatites; relatively common in replacement ores at Franklin, NJ, and Falun, Sweden. Syn: zinc spinel.

gahnospinel
 * A blue magnesian variety of gahnite used as a gem, from Sri Lanka.

gain
 * a. A cutting made in the side of a roadway underground to facilitate the construction of a dam or air stopping.

b. A crosscut in coal mining. c. See: closed joint. d. A notch, mortise, or groove (as in a timber or wall) for a girder or joist. e. The ratio of the output power, voltage, or current to the input power, voltage, or current.

gaize
 * a. A siliceous rock containing some clay in the Ardennes and Meuse Valley, France.

b. A porous fine-grained micaceous glauconitic sandstone containing much soluble silica among the Cretaceous rocks of France and Belgium; a calcareous sediment cemented by chert or flint.

Gal
 * A unit of acceleration, used in gravity measurements: 1 Gal = 1 cm/s (super 2) . The Earth's normal gravity is 980 Gal. The term is not an abbrev.; it was invented to honor the memory of Galileo. See also: milligal.

galactite
 * a. A variety of natrolite found as colorless acicular crystals.

b. An obsolete syn. of novaculite. c. An unidentified stone (possibly calcium nitrate) whose milky solution gave rise to several medieval legends and superstitions.

galaxite
 * An isometric mineral, (Mn (super +2) ,Fe (super +2) ,Mg)(Al,Fe (super +3) ) (sub 2) O (sub 4) ; spinel group; occurs as black grains in Galax, Alleghany County, NC; Ioi Mine, Shiga Prefecture, and Oashi mine, Tochigi Prefecture, Japan.

gale alidade
 * A lightweight compact alidade, with a low pillar and a reflecting prism through which the ocular may be viewed from above. As used by some geologists, it is commonly equipped with the Stebinger drum. See also: Stebinger drum. Syn: explorer's alidade.

galeite
 * A trigonal mineral, Na (sub 15) (SO (sub 4) ) (sub 5) F (sub 4) Cl ; occurs embedded in clay associated with gaylussite and northupite in drill cores from Searles Lake, CA. CF: schairerite.

galena
 * An isometric mineral, 4[PbS] ; cubic cleavage; forms cubes and octahedra, also coarse- or fine-grained masses; sp gr, 7.6; occurs with sphalerite in hydrothermal veins, also in sedimentary rocks as replacement deposits; an important source of lead and silver. Also spelled galenite. Syn: lead sulfide; galenite. See also: blue lead.

galenite
 * See: galena.

galenobismutite
 * An orthorhombic mineral, PbBi (sub 2) S (sub 4) ; soft; massive, or in needlelike to lathlike crystals in radiating aggregates, commonly intergrown with bismuthinite and other bismuth minerals; sp gr, 7.04 to 7.15; occurs in high-temperature replacement deposits or veins; may be argentiferous (e.g., the variety alaskaite in Colorado) or selenian (e.g., the variety selenbleiwismuthglanz at Falun, Sweden); a source of bismuth.

gallatin
 * The heavy oil of coal tar used in the Bethell process for the preservation of timber. Also called dead oil.

gallery
 * a. A mine level, drift, tunnel, or passage.

b. A large, more or less horizontal, passage in a cave. c. A subsurface collector for intercepting ground water. d. A horizontal or nearly horizontal underground passage, either natural or artificial. e. A subsidiary passage in a cave at a higher level than the main passage. f. A drift or adit. g. An underground conduit or reservoir. h. Underground road. i. A passageway, as in a dam.

gallery of efflux
 * Eng. A drain tunnel or adit.

gallery testing
 * Testing conditions designed to resemble those existing underground as closely as possible, and to reproduce what was considered to be the most dangerous condition, namely, a blownout shot discharging into the most easily ignited mixture of combustible gases and air.

galliard
 * A hard, smooth, close-grained, siliceous sandstone; a ganister. Also spelled: calliard.

galliard balls
 * Large ironstone concretions in sandstones, Yorkshire, U.K.

gallite
 * A tetragonal mineral, CuGaS (sub 2) ; chalcopyrite group; forms grains and inclusions in germanite and renierite, and exsolution lamellae in sphalerite and pyrite-sphalerite assemblages at Tsumeb, Namibia, and Shaba Province, Zaire.

gallium arsenide
 * Dark gray; GaAs; isometric; melting point, 1,240 degrees C. Used in microwave diodes and in high-temperature rectifiers and transistors.

gallium oxide
 * Ga (sub 2) O (sub 3) ; melting point, 1,795+ or -15 degrees C.

Galloway stage
 * Multidecked platform suspended near bottom of shaft during sinking. It carries part of the equipment in use and can be raised or lowered as required during blasting, mucking, wall concreting, etc. See also: pentice.

gallows timber
 * A timber framework or set for roof support.

galmei
 * See: calamine.

galvanic cell
 * An electrolytic cell that is capable of producing electric energy by electrochemical action. See also: cell.

galvanic corrosion
 * a. Corrosion associated with the current of a galvanic cell consisting of two dissimilar conductors in an electrolyte or two similar conductors in dissimilar electrolytes. Where the two dissimilar metals are in contact, the resulting reaction is referred to as couple action.

b. The corrosion above normal corrosion of a metal that is associated with the flow of current to a less active metal in the same solution and in contact with the more active metal.

galvanic electromagnetic methods
 * Electrical exploration methods in which electric current is introduced in the ground by means of contact electrodes and in which one determines the magnetic field that is associated with the current.

galvanize
 * To coat with zinc.

galvanizing
 * Immersion of clean steel or iron in bath of molten zinc for purpose of forming a protective coating. Sherardizing is the process of heating iron articles with zinc dust to a temperature at which a strong adherent coating is formed. Electrolytic galvanizing is the electrodeposition of zinc on the iron. See also: hot-dip coating.

galvanoscope
 * An instrument employed for detecting an electric current and showing its direction. It differs from a galvanometer in being only qualitative.

galvanothermometer
 * An instrument for measuring the heat generated by an electric current or for measuring the current by the heat that it generates.

gamagarite
 * A monoclinic mineral, (Ba (sub 2) (Fe,Mn)(VO (sub 4) ) (sub 2) (OH) ; brackebuschite group; forms prismatic crystals and aggregates of needles with diaspore, ephesite, and bixbyite in manganese ore at Gamagara ridge, Postmasburg, Republic of South Africa.

gamella
 * Braz. A wooden bowl, about 2 ft (0.6 m) wide at the mouth, and 5 in or 6 in (12.7 cm or 15.2 cm) deep, used for washing gold out of the auriferous material collected in sluices and in river sand. Syn: batea.

gamma
 * a. In a biaxial crystal, the largest index of refraction.

b. The interaxial angle between the a and b crystallographic axes. CF: alpha; beta. c. The cgs unit of magnetic field intensity commonly used in magnetic exploration. It is equal to 10 (super -5) Oe (7.957747 X 10 (super -4) A/m). Syn: nanotesla. d. adj. Of or relating to one of three or more closely related minerals and specifying a particular physical structure (esp. a polymorphous modification); specif. said of a mineral that is stable at a temperature higher than those of its alpha and beta polymorphs (e.g., gamma quartz or gamma -quartz).

gamma-gamma log
 * A borehole measurement of gamma rays originating in a gamma-ray source in the instrument and scattering back from the rock formation to a detector shielded from the source. The amount of scattering is proportional to electron density and, therefore, proportional to mass concentration so that the measurement, after certain corrections, yields a density log of the formation penetrated.

gammagraphy
 * In the United States a term for inspection by gamma rays.

gamma iron
 * The face-centered cubic form of pure iron, which is stable from 1,670 to 2,550 degrees F (910 to 1,400 degrees C).

gamma radiation
 * Emission by radioactive substances of quanta of energy corresponding to X-rays and visible light but with a much shorter wavelength than light. May be detected by gamma-ray Geiger counters.

gamma-ray probe
 * A gamma-ray counter device built into a watertight case small enough in diameter to be lowered into a borehole.

gamma rays
 * High-energy, short-wavelength, electromagnetic radiation emitted by a nucleus. Energies of gamma rays are usually between 0.010 and 10 million eV. X-rays also occur in this energy range but are of nonnuclear origin. Gamma radiation usually accompanies alpha and beta emissions and always accompanies fission. Gamma rays are very penetrating and are best attenuated by dense materials like lead and depleted uranium.

gamma-ray spectrometer
 * An instrument for measuring the energy distribution, or spectrum, of gamma rays, whether from natural or artificial sources. It is used in airborne remote sensing for potassium, thorium, and uranium.

gamma-ray spectrometer log
 * A log that measures the relative quantities of potassium, thorium, and uranium present in the rocks penetrated by a borehole.

gamma-ray well log
 * The radioactivity log curve of the intensity of broad-spectrum, undifferentiated natural gamma radiation emitted from the rocks in a cased or uncased borehole. It is used for correlation, and for distinguishing shales (which are usually richer in naturally radioactive elements) from sandstones, carbonates, and evaporites. CF: spectral gamma-ray log. See also: radioactivity log.

gamma-ray well logging
 * A method of logging boreholes by observing the natural radioactivity of the rocks through which the hole passes. It was developed for logging holes that cannot be logged electrically because they are cased.

gamma sulfur
 * See: rosickyite.

gamma zircon
 * A metamict variety of zircon that is nearly amorphous owing to radiation damage; it has lower density than crystalline zircon.

gang
 * a. A train or set of mine cars or trams.

b. A mine. c. A set of miners. d. Gangue.

gang car
 * A car that may be loaded with a block of stone and placed beneath the blades of a gang saw. It is a substitute for the stationary saw bed.

gang drill
 * A set of drills in the same machine operated together.

ganger
 * A work gang foreman.

gang filler
 * In the stonework industry, one who attaches and detaches crane slings or hooks to and from blocks or slabs of granite, marble, and stone in loading the stone on gang saw cars or trucks and pulling them under the gang saws.

gang miner
 * In bituminous coal mining, one who works in a group that pools its earnings regardless of the type of work performed (drilling, undercutting, blasting, or loading coal).

gangue
 * The valueless minerals in an ore; that part of an ore that is not economically desirable but cannot be avoided in mining. It is separated from the ore minerals during concentration. CF: ore mineral.

gangway
 * a. A main haulage road underground. Frequently called entry.

b. A passageway driven in the coal at a slight grade, forming the base from which the other workings of the mine are begun. c. A passageway or avenue into or out of any enclosed place, as in a mine. d. An elevated roadway. e. Pennsylvania. Generally confined to anthracite mines. f. Newc. A wooden bridge.

gangway cable
 * A cable designed to be installed horizontally (or nearly so) for power circuits in mine gangways and entries.

ganister
 * a. A hard, fine-grained quartzose sandstone or quartzite, used in the manufacture of silica brick. It is composed of subangular quartz particles, cemented with secondary silica, and possessing a characteristic splintery fracture. Ganister is distinguished from chert by its more granular texture and by the relatively small quantity of chalcedonic or amorphous silica.

b. A mixture of ground quartz and fireclay used as a furnace lining. Also spelled gannister. c. See: quartzite.

gannen
 * N. of Eng. A road (heading) down which coal is conveyed in cars running upon rails. An inclined gangway in a coal mine.

gantlet
 * A narrowing of two single railway tracks almost into the space of one, as on a bridge or in a tunnel, without breaking the continuity of either track by a switch, the two tracks overlapping each other.

gantry
 * a. A frame erected on a gold dredge for supporting different parts of the machinery. Also spelled: gauntry; gauntree.

b. A bridge or platform carrying a traveling crane or winch and supported by a pair of towers, trestles, or side frames running on parallel tracks. c. An overhead structure that supports machines or operating parts. d. An upward extension of a shovel revolving frame that holds the boom line sheaves.

Gantt chart
 * Construction program for major engineering works, set out in graphic form. Down the vertical axis in sequence are set out the items concerned. The abscissa shows the period covered in days, or weeks, and the period allowed for each item marked by a horizontal line. The chart displays the interrelation between the items, and aids in ensuring that no item is so delayed as to impede progress on a later one that depends on it.

gap
 * In a fault, the horizontal component of separation measured parallel to the strike of the strata, with the faulted bed absent from the measured interval.

gape
 * Maximum aperture at entry to a coarse crushing machine at which the largest piece of rock fed to it can be gripped and acted on by the breaking system.

gap packing
 * A method of packing for road maintenance that consists of gate side packs 3 to 5 yd (2.7 to 4.6 m) wide, next a gap of at least the width of the road, and finally a large pack 5 to 7 yd (4.6 to 6.4 m) wide. The waste packs are made at least 2 yd (1.8 m) wide and not less in width than twice the thickness of the seam. The gaps provided in strip packing are kept clear of supports and allow the roof to break up and flow toward them. This puts the strata in tension over the roads and reduces fracture and crush.

gap sensitivity
 * The maximum distance for propagation between standard cartridge sizes separated by an air gap. CF: sympathetic detonation.

gap test
 * The gap is the greatest distance at which, under certain given conditions, a priming cartridge is capable of initiating a receiving cartridge (receptor). The same explosive is usually used both as primer and receptor, although the gap distance in such a case will also be affected by any change in strength that may occur in the explosive. The gap test can be carried out with the cartridges unconfined or confined, for example, in tubes, in air, or in water. The test gives, for example, information about changes in the explosive due to aging, moisture, temperature, etc.

garbenschiefer
 * a. A type of spotted slate characterized by concretionary spots whose shape resembles that of a caraway seed. Etymol: German. CF: fleckschiefer; fruchtschiefer.

b. See: feather amphibolite.

Gardner crusher
 * A swing and hammer crusher, the hammers being pieces hung from trunnions between two disks keyed to a shaft. When revolved, centrifugal force throws the hammers out against the feed and a heavy anvil inside the crusher housing.

gargarinite
 * A hexagonal mineral, NaCaY(F,Cl) (sub 6) ; in albitized granites and associated quartz-microcline veins in Kazakhstan.

gargulho
 * A Brazilian term used in the plateau region of Bahia for a comparatively coarse, clay-cemented, ferruginous conglomerate in which diamonds are found.

garland
 * a. A channel fixed around the lining within a shaft in order to catch the water draining down the shaft walls and conduct it by pipes or water boxes to a lower level. Also called water curb; water garland. See also: water ring.

b. A frame to heighten and increase content of a truck.

garnet
 * a. A group of isometric minerals having the general formula A (sub 3) B (sub 2) (SiO (sub 4) ) (sub 3-2Dx) (OH) (sub 4x) in which A=(Ca,Fe,Mg,Mn) and B=(Al,Cr,Fe,Mn,Si,Ti,V,Zr) with Si partly replaced by (Al,Fe).

b. The silicate minerals almandine, andradite, calderite, goldmanite, grossular, hibshite, katoite, kimzeyite, knorringite, majorite, pyrope, schlorlomite, spessartine, and uvarovite. Syn: granat.

garnet doublet
 * a. A term applied to the most common doublet, that with a very thin top of red garnet, regardless of the color of the doublet.

b. Any doublet of dark red color regardless of whether any portion of it is garnet, more correctly called a garnet-top doublet. c. A composite stone made with a garnet top on a glass base. Also called garnet-top doublet, garnet-topped doublet.

garnetite
 * A metamorphic rock consisting chiefly of an aggregate of interlocking garnet grains. CF: tactite.

garnetization
 * Introduction of, or replacement by, garnet. This process is commonly associated with contact metamorphism.

garnet jade
 * A light-green variety of grossular garnet closely approaching fine jadeite in appearance, esp. that in Transvaal, South Africa.

garnetoid
 * A group of nonsilicate minerals that are isostructural with garnet, including the oxide yafsoanite, the arsenates berzeliite and manganberzeliite, and the halide cryolithionite. CF: hydrogrossular; hydrogarnet.

garnierite
 * A general term for hydrous nickel silicates. Syn: genthite; noumeite.

garrelsite
 * A monoclinic mineral, Ba (sub 3) NaSi (sub 2) B (sub 7) O (sub 16) (OH) (sub 4) ; in colorless crystals associated with nahcolite and shortite in core from an oil boring at Ouray, CO.

garronite
 * An orthorhombic mineral, Na (sub 2) Ca (sub 5) Al (sub 12) Si (sub 20) O (sub 64) .27H (sub 2) O ; zeolite group; pseudotetragonal; forms radiating aggregates in amygdules in basalts, commonly associated with other zeolites, e.g., chabazite, thomsonite, and levyne; at the Garron Plateau, County Antrim, Ireland, and 22 localities in eastern Iceland.

gas
 * a. Combustible gases (methane), a mixture of air and combustible gases, or other explosive gaseous mixture encountered in mining.

b. A fluid of low density and of high compressibility. The specific recognition of a gas as distinct from a liquid of the same composition requires the simultaneous presence of both phases at equilibrium. See also: fluid; vapor. c. In mining, a mixture of atmospheric air with combustible gases. d. The term normally used by miners to designate any impure air, esp. explosive combinations. e. The term generally applied to denote combustible gases. f. Any aeriform liquid other than atmosphere air, such as gaseous carbon dioxide (blackdamp), carbon monoxide (whitedamp), methane (combustible gases), and the common combustible petroleum-product gases. CF: acetylene. g. Abbrev. for gasoline. See also: manufactured gas; natural gas. h. A fluid (as air) that has neither independent shape nor volume but tends to expand indefinitely. A substance at a temperature above its critical temperature and therefore not liquefiable by pressure alone. i. As a verb, to affect or to treat with gas. To subject to the action of gas.

gas alarm
 * Device or signal system that warns underground workers of dangerous concentration of combustible gases.

gas analysis
 * An analysis of mine air to give information regarding the oxygen content of the air and the presence of explosive or otherwise undesirable gas or gases. It is a valuable aid in following the changes in mine air during fires and after explosions.

gas bubble
 * a. Round inclusion in glass, synthetic corundum, and spinel, which reveal their difference from native corundum, spinel, and most other native gemstones, in which inclusions are negative crystals. Syn: glass enclosure; gas enclosure.

b. Relatively rare type of fluid inclusions created where a gas such as carbon dioxide is trapped in minerals growing from gas-saturated or boiling liquids, identified by their tubular gas-filled structures.

gas carburizing
 * The introduction of carbon into the surface layers of mild steel by heating in a current of gas high in carbon--usually hydrocarbons or hydrocarbons and carbon monoxide.

gas centrifuge process
 * A method of isotope separation in which heavy atoms are separated from light atoms by centrifugal force.

gas classification
 * The separation of powder into particle-size fractions by means of a gas stream of controlled velocity.

gas concrete
 * Coke formed in gas retorts as distinguished from that made in a coke oven.

gas conductor
 * A pipe for leading combustion gases from the mouth of a blast furnace to a hot-blast stove.

gas detonation system
 * A system for initiating blasting caps in which the energy is transmitted through the circuit by means of a gas detonation inside a hollow plastic tube. See also: nonelectric blasting; shock tube system.

gas drain
 * a. Eng. A heading driven in a mine for the special purpose of carrying off methane from any workings.

b. A tunnel or borehole for conducting gas away from old workings.

gas emission
 * The release of gas from the strata into the mine workings.

gas-emission rate
 * The quantity of methane discharged from the strata and coal seams into the ventilating air of a coal mine. The rate may be expressed on a time or tonnage basis. Gas emission varies with (1) the rate of advance of the workings; (2) the face operation such as cutting, blasting, loading, etc.; and (3) the barometric reading.

gas enclosure
 * See: gas bubble.

gaseous
 * a. Having the form of or being gas; of or relating to gases.

b. Lacking substance or solidity.

gaseous diffusion
 * A method of isotope separation based on the fact that atoms or molecules of different masses will diffuse through a porous barrier at different rates. The method is used to enrich uranium with the uranium-235 isotope.

gaseous dispersion pattern
 * A dispersion pattern that may be detected by analysis of soil, air, or gas dissolved in underground water, or of gas condensed in the rocks and soil. Gaseous dispersion patterns of interest include those of hydrocarbons and some noble gases resulting from nuclear decay of radioactive elements, and gaseous substances such as Hg, H (sub 2), He, SO (sub 2) , CO (sub 2) , and CS (sub 2).

gaseous fuel
 * Includes natural gas and the prepared varieties, such as coal gas, oil gas, and iron blast furnace gas, as well as producer gas, etc.

gaseous place
 * A place that is likely to be dangerous from the presence of flammable gas.

gaseous transfer
 * Separation from a magma of a gaseous phase that moves relative to the magma and releases dissolved substances, usually in the upper levels of the magma, when it enters an area of reduced pressure.

gas evolution
 * The liberation of gas in the form of bubbles during the solidification of metals. It may be due to the fact that the solubility of a gas is less in the solid and liquid metal respectively, as when hydrogen is evolved by aluminum and its alloys, or to the promotion of a gas-forming reaction, as when iron oxide and carbon in molten steel react to form carbon monoxide. See also: blowhole; unsoundness.

gas explosion
 * A major or minor explosion of combustible gases in a coal mine, in which coal dust apparently did not play a significant part. See also: coal-dust explosion.

gas firing
 * The combustion of coal effected by burning in such a way as to produce a combustible gas, which is then burned secondarily in the laboratory or the furnace.

gas-flame coal
 * Coal containing 35% to 40% volatiles (dry, ashless basis).

gas fluxing
 * a. The addition of gaseous materials as a flux to promote melting.

b. A rapid upward streaming of free juvenile gas through a column of molten magma in the conduit of a volcano. The gas acts as a flux to promote melting of the wall rocks.

gas grooves
 * Hills and valleys in electrolytic deposits caused by streams of hydrogen or other gas rising continuously along the surface of the deposit while it is forming.

gash fracture
 * A small-scale tension fracture that occurs at an angle to a fault and tends to remain open.

gash vein
 * A nonpersistent vein that is wide above and narrow below, and that terminates within the formation it traverses. The term was originally applied to vein fillings in vertical solution joints in limestone.

gasification
 * Conversion of coal to gaseous fuel without leaving a combustible residue.

gas ignition
 * The setting on fire of a small or large accumulation of combustible gases in a coal mine. The ignition may be caused by a safety lamp, electrical machinery, explosives, frictional sparking, etc. Syn: ignition of combustible gases.

gas indicator
 * A pocket device for the rapid determination of the percentage of a specific gas in the atmosphere of mines, boiler rooms, blast furnaces, etc.

gas-logged strata
 * Rock formations, usually in coal mines, that contain a relatively high proportion of methane. In descensional ventilation, the buoyancy pressure of the methane opposes the ventilating pressure, with a tendency for cavities to contain combustible gases of high concentration. The same may apply to waste cavities with no natural exit to the return.

gasman
 * An underground official who examines the mine for combustible gases and has charge of their removal. See also: fire boss; gas watchman.

gas pipe
 * a. Mid. A short wooden pipe about 4 in by 4 in (10.2 cm by 10.2 cm) inside, having its upper end open to the roof, and the lower end opening into the bratticing so that any gas given off in the roof may be carried away as formed.

b. Any pipe for conveying gas.

gas pocket
 * A cavity in the rocks containing gas, generally above an oil pocket.

gas pore
 * A gas bubble in a mineral.

gas pressure
 * The forces generated from the expansion of gases formed from the reaction of explosive materials after detonation; gas pressures produce the heaving action during rock blasting. Syn: borehole pressure.

gas producer
 * A furnace in which coal is burned for the manufacture of producer gas. There are two types: (1) the step-grate, natural-draft generator, which is but a development of the ordinary firebox; and (2) the shaft furnace, with or without a grate and worked by a natural or forced draft. The latter type is identical in many respects to a blast smelting furnace.

gas ratio
 * The ratio of the volume at atmospheric pressure of the gas developed by an explosive to the volume of the solid from which it was formed. Many commercial explosives have a gas ratio of about 8. Ammonium nitrate plus fuel oil has a ratio of about 20.

gas reverser
 * In the iron and steel industry, one who reverses gas valves by manipulating levers to throw hot combustion gases from one side of the furnace to the other, to keep the furnace heat evenly distributed, and to prevent burning out on one side.

gas rig
 * A borehole drill, either rotary or churn-drill type, driven by a combustion-type engine using a combustible liquid, such as gasoline, or a combustible gas, such as bottle gas, as the source of the motivating energy.

gassing
 * a. Absorption of gas by a metal.

b. Evolution of gas from a metal during melting operations or on solidification. c. The evolution of gas from an electrode during electrolysis.

gassing of copper
 * A process that denotes the brittleness produced when copper containing oxide is heated in an atmosphere containing hydrogen. The hydrogen diffuses into the metal and combines with oxygen, forming steam that cannot diffuse out. A high steam pressure is built up at the crystal boundaries, and the cohesion is diminished.

gas spectrum
 * a. The spectrum, consisting of bright lines or bands, obtained by dispersing the light from a glowing gas or vapor.

b. An absorption spectrum obtained by passing light through a gas or vapor.

gas streaming
 * A process of magmatic differentiation involving the formation of a gaseous phase, usually during a late stage in consolidation of the magma, that results in partial expulsion, by escaping gas bubbles, of residual liquid from the crystal network.

gassy
 * A mine is said to be gassy when it gives off methane or other gas in quantities that must be diluted with pure air to prevent occurrence of explosive mixtures.

gas tracers
 * Slowly moving air currents can be directly observed by using smokes. These may range from simple dust clouds, through various chemical smokes, to more refined techniques employing gas and radioactive tracers. Various chemicals have been used, including stannic chloride, titanium tetrachloride, and pyrosulfuric acid. These materials give off white fumes when their vapors come into contact with atmospheric moisture. The method in common use is to carry the chemical in sealed glass ampules, which can be broken when an observation is to be made.

gas trap
 * One of many devices for separating and saving the gas from the flow and lead lines of producing oil wells. The mixture of oil and gas is allowed to flow through a chamber large enough to reduce the velocity of the mixture to the point at which the oil and gas tend to separate. The gas, seeking the top of the chamber, is drawn off free of oil, while the oil is discharged at the bottom. Also called gas tank.

gastrolith
 * A rounded stone or pebble, commonly highly polished, from the stomach of some reptiles, esp. dinosaurs, plesiosaurs, and crocodilians. Gastroliths are thought to have been used in grinding up food, but marine reptiles may have used them to provide body stability while in the water.

gastropod
 * Any mollusk belonging to the class Gastropoda, characterized by a distinct head with eyes and tentacles and, in most, by a single calcareous shell that is closed at the apex, sometimes spiralled, not chambered, and generally asymmetrical; e.g., a snail. Range, Upper Cambrian to present.

gastunite
 * See: weeksite.

gas watchman
 * In bituminous coal mining, person who makes morning examinations for gas before workers enter the mine. See also: fireman; fire boss; gasman.

gas water
 * Water through which coal gas has been passed and which has absorbed the impurities of the gas.

gate
 * a. Eng. Gateway or gate road. A road or way underground for air, water, or general passage; a gangway. See also: gate end.

b. Eng. A road packed out in longwall goaf. When ripped in the waste to provide packing material on a conveyor face, it is called a dummy gate. Also called gate road; gateway; main brow; trail road. c. The apparatus at the bottom of an ore chute for filling cars. Also called a chute. d. Syn: swivel head. Also, the swivel ring of the swivel head of a diamond drill. e. The closing piece in a stop valve. f. A valve controlling the admission of water to a waterwheel or conduit.

gate belt conveyor
 * Conveyor usually from 26 to 30 in (66.0 to 76.2 cm) wide and troughed so as to centralize the load and minimize spillage. A scraper feeder, consisting of an elevating chain conveyor driven by the gate belt, is often used to transfer the coal from the face belt to the gate belt.

gate conveyor
 * A gate road conveyor that carries coal from one source or face only; i.e., from a single-unit or double-unit face. See also: conveyor; face conveyor; gathering conveyor.

gate end
 * The coal face or inby end of a gate. See also: gate.

gate-end box
 * A flameproof enclosure primarily for use at or near the coalface and designed to line up with similar boxes to form a control board. A gate-end box may contain bus bars, isolators, switches, contactors, transformers, and protective devices, for the control of motors, lighting, and other equipment. Syn: gate-end unit.

gate-end feeder
 * A short conveyor that feeds the coal from the face conveyor onto the gate conveyor. See also: feeder conveyor.

gate-end loader
 * A short conveyor designed to receive the coal from the face conveyors and elevate it to such a height as to be convenient for delivery into mine cars. See also: feeder conveyor.

gate-end switch
 * A flameproof motor-starting contactor for use with coal-face machinery. The essential features are a flameproof casing divided into two separate compartments, the smaller of which contains a hand-operated isolating switch and the main bus bars. The isolating switch is interlocked with the cover of the main compartment so that it cannot be removed unless the switch is in the off position; or it may be fitted with contacts enabling the mechanism to be earthed before work is undertaken on it.

gate-end unit
 * See: gate-end box.

gate interlock
 * A system designed to prevent shaft conveyances from being moved or action signals from being transmitted, unless all shaft gates are closed.

gate road
 * a. Eng. A road connecting a stall with a main road.

b. A road through the goaf used for haulage of coal from longwall working.

gate road bunker
 * An appliance for the storage of coal from the face conveyors during peaks of production or during a stoppage of the outby transport. It may consist of a length of conveyor chain running in high-capacity pans arranged under the delivery end of the gate conveyor. When the trunk conveyor cannot handle the coal from the gate conveyor, the bunker chain is slowly drawn back carrying about 1 st (0.9 t) of coal per yard of chain. The bunker is later discharged by reversing the process. See also: underground bunker.

Gates canvas table
 * A large form of inclined canvas table in which the pulp is first classified, then distributed along the upper edge of the table. The concentrates are caught in the warp of the canvas; after this is full, treatment must be stopped while the concentrates are swept or sluiced off.

gate shutter
 * A paddlelike implement used to shut off the flow of metal from a mold and divert it to other molds.

gate side pack
 * A pillar consisting of tightly rammed material enclosed in walls of stone, built on each side of the gate road. See also: double packing.

gateway longwall
 * N. of Eng. A continuous coal face served by gateways (in Durham about 12 yd or 11 m apart). A small group works in each gateway down which the coal is removed by tubs.

gather
 * To assemble loaded cars from several production points and deliver them to main haulage for transport to the surface or pit bottom.

gathering arm loader
 * A machine for loading loose rock or coal. It has a tractor-mounted chassis, carrying a chain conveyor the front end of which is built into a wedge-shaped blade. Mounted on this blade are two arms, one on either side of the chain conveyor, which gather the material from the muck pile and feed it onto the loader conveyor. The tail or back end of the conveyor is designed to swivel and elevate hydraulically so that the coal or stone can be loaded into a car or on to another conveyor. See also: loader.

gathering conveyor
 * Any conveyor that is used to gather coal from other conveyors and deliver it either into mine cars or onto another conveyor. The term is frequently used with belt conveyors placed in entries where a number of room conveyors deliver coal onto the belt. See also: gate conveyor; trunk conveyor.

gathering ground
 * See: catchment area.

gathering haulage
 * That portion of the haulage system immediately adjacent to the face. In longwall mining, the face belt or tubs and track along the face constitute the gathering haulage system.

gathering locomotive
 * See: gathering motor; electric gathering mine locomotive.

gathering mine locomotive
 * See: gathering motor; electric gathering mine locomotive.

gathering motor
 * A lightweight type of electric locomotive used to haul loaded cars from the working places to the main haulage road and to replace them with empties. Syn: gathering locomotive; gathering mine locomotive. See also: electric gathering mine locomotive.

gathering motorman
 * In bituminous coal mining, a person who operates a mine locomotive to haul loaded mine cars from working places to sidings, for the formation of larger trips (trains) to be handled by a haulage cable or a main-line locomotive. Syn: relay motorman.

gathering pumps
 * Portable or semiportable pumps that are required when water is encountered while opening a new mine, for extending headings or entries in an operating mine, for pumprooms or rib sections lying in the dip, for collecting water from local pools, or for sinking a shaft. They discharge water at an intermediate pumping station or into a drainage ditch or tunnel carrying water outside a mine.

gatton
 * Scot. See: gauton.

gaudefroyite
 * A hexagonal mineral, Ca (sub 4) Mn (sub 3) (BO (sub 3) ) (sub 3) (CO (sub 3) )(O,OH) (sub 3) ; forms prisms associated with marokite, braunite, and hasumannite in calcite from Tachgagalt, Morocco.

Gaudin's equation
 * An equation for the particle size distribution that can be expected when a material is crushed in a ball mill or rod mill; it is of the form P = 100(x/D)m, where P is the percentage passing a sieve of aperture x, D is the maximum size of particle, and m is a constant which is a measure of dispersion. The equation holds good only if the ratio of size of feed to size of balls is below a critical value.

gauge
 * See: gage.

gault
 * Firm compact clay; brick clay. Also spelled galt, golt.

gauntree
 * See: gantry.

gauslinite
 * A local name for burkeite. From Searles Lake, Calif. See also: burkeite. Syn: teepleite.

gauss
 * Unit of magnetic induction in the electromagnetic and Gaussian systems of units, equal to 1 Mx/cm (super 2) (10 nWb/cm (super 2) ), or 10 (super -4) Wb/m (super 2) . Also known as abtesla (abt).

gaussian model
 * A function frequently used when fitting mathematical models to experimental variograms, often in combination with a nugget model.

gauton
 * Scot. A watercourse cut in the floor of a mine or working. Syn: gatton. See also: hasson.

gawl
 * An irregular or uneven line of coal face.

gayet
 * a. French name for sapropelic coal, such as torbanite or cannel.

b. See: cannel coal.

Gayley process
 * The process for the removal of moisture from the blast of an iron blast furnace by reducing the temperature of the blast current so that the moisture is deposited as snow. See also: cold blast.

Gay-Lussac's law
 * When gases react, they do so in volumes that bear a simple ratio to one another, and to the volumes of their products if these are gaseous, temperature and pressure remaining constant. Also called law of gaseous volumes.

Gay-Lussac's tower
 * In sulfuric acid making, a tower filled with pieces of coke over which concentrated sulfuric acid trickles down. On meeting gas issuing from the lead chambers, the coke absorbs nitrous anhydride, which otherwise would be lost. CF: Glover's tower.

gaylussite
 * A monoclinic mineral, Na (sub 2) Ca(CO (sub 3) ) (sub 2) .5H (sub 2) O ; soft; in flattened and elongated crystals in muds from playa lakes in the Mohave Desert, CA, and the Gobi Desert, Mongolia.

geanticline
 * a. A mobile upwarping of the crust of the Earth, of regional extent. Ant: geosyncline.

b. More specif., an anticlinal structure that develops in geosynclinal sediments, due to lateral compression. Var: geoanticline.

gear
 * a. The moving parts or appliances collectively that constitute some mechanical whole or set, linked meshing and fitted together, and serving to transmit motion or change its rate or direction. Commonly used in the plural.

b. A gear wheel. c. See: feed gear. d. The accessory tools and equipment required to operate a drill. e. A set of enmeshing-toothed rotating parts or cogwheels designed to transmit motion. f. A toothed wheel, cone, or bar.

gearksutite
 * A monoclinic mineral, CaAl(OH)F (sub 4) .H (sub 2) O ; occurs with fluorite and barite in hydrothermally altered sedimentary and volcanic rocks.

gearman
 * In beneficiation, smelting, and refining, one who tends a coarse or primary crusher that breaks large lumps of ore into a smaller size so that it may be run through smaller crushers or shipped to a plant for extraction of the valuable metal or minerals.

gear ratio
 * The relationship between the speeds of the first and last shafts, respectively, of a train of gears. If a certain force drives a machine at a given speed and the output shaft runs at one-tenth of the speed of the input shaft, then the output force will be 10 times the input. If the gear ratio of a motor-driven machine is 10 to 1, then the turning force of the last shaft will be 10 times that of the motor, apart from force used up in friction.

gear set
 * A device that causes one shaft to turn another at reduced speed.

Gebhardt survey instrument
 * A borehole surveying instrument often used to test the verticality of the freezing holes in shaft sinking. A vernier scale is used to determine the positions of the pendulum points at successive points, and by summating the results an accurate plan of the course of the borehole can be prepared.

gedanite
 * A brittle wine-yellow variety of amber with very little succinic acid; lacks the toughness and ability to take as high a polish as the succinic acid-rich varieties; rarely used as a gem except for beads. Syn: mellow amber.

gediegen
 * See: zinn.

gedrite
 * An orthorhombic mineral, (Mg,Fe) (sub 5) Al (sub 2) [Si (sub 6) Al (sub 2) O (sub 22) ](OH) (sub 2) ; amphibole group, with Mg/(Mg + Fe) = 0.1-0.89; forms series with magnesiogedrite and ferrogedrite; common in schists, gneisses, and metasomatic rocks.

geest
 * a. Alluvial material that is not of recent origin lying on the surface. An example is the sandy region of the North Sea coast in Germany.

b. See: saprolite.

gehlenite
 * A tetragonal mineral, Ca (sub 2) Al(AlSi)O (sub 7) ; melilite group; forms a series with akermanite; a common constituent of feldspathoidal rocks formed by reaction of mafic magmas with carbonate rocks. Syn: velardenite.

Geiger counter
 * a. An ionization chamber that records the number of radioactive particles impinging upon it per minute, thus detecting radioactive substances.

b. An instrument that detects gamma rays given off by radioactive substances. c. An ionization chamber with its vacuum and its applied potential so adjusted that a gamma ray or other ionizing particle passing through it causes a momentary current to flow. The surge of current can be amplified and counted so as to measure the intensity of radioactivity in the vicinity of the chamber.

Geiger-Mue
 * A gas-filled chamber usually consisting of a hollow cylindrical cathode and a fine wire anode along its axis. It is operated with a voltage high enough so that a discharge triggered by a primary ionizing event will spread over the entire anode until stopped by the reduction of the field by space charge.

Geiger-Mueller counter
 * An instrument consisting of a Geiger-Mueller tube plus a voltage source and the electronic equipment necessary to record the tube's electric pulses. Also called Geiger counter.

Geiger-Mueller tube
 * A Geiger-Mueller counter encased in a watertight container, which can be lowered into a borehole and used to log the intensity of the gamma rays emitted by the radioactive substances in the rock formations traversed. Syn: Geiger probe. M(  ��6 �"6 ��� �       � '�DICTIONARY TERMS:Geiger-Mueller tube A radiation detector consisting A radiation detector consisting of a gas-filled tube with a cathode envelope and an axial wire anode. It functions by producing momentary current pulses caused by ionizing radiation. It is a part of the Geiger-Mueller counter. Syn: G-M tube.

Geiger probe
 * See: Geiger-Mueller probe.

Geiger test
 * The act or process of using a Geiger-Mueller probe or counter to measure the intensity of the gamma rays emitted by the radioactive substance contained in rocks traversed by a borehole.

geikielite
 * A trigonal mineral, MgTiO (sub 3) ; ilmenite group; forms a series with ilmenite; in highly metamorphosed magnesian marbles associated with brucite, spinel, or diopside; in serpentinites with chromium-rich chlorites, and in gem gravels of Sri Lanka.

Geissler tube
 * a. A sealed and partly evacuated glass tube containing electrodes. Used for the study of electric discharges through gases.

b. A gas-filled discharge tube having various shapes and usually containing a narrowly constricted portion in which the luminosity is intensified.

gel
 * a. A translucent to transparent, semisolid, apparently homogeneous substance in a colloidal state, generally elastic and jellylike, offering little resistance to liquid diffusion, and containing a dispersion or network of fine particles that have coalesced to some degree.

b. A nonhomogeneous gelatinous precipitate; e.g., a coagel. c. A liquefied mud, which became firm and then reabsorbed most of the water released earlier. A gel is in a more solid form than a sol, and can sustain limited shear stress. See also: thixotropy.

Gelamite
 * Trademark for a semigelatin high explosive of relatively high weight strength of 65%; very good water resistance. Used in underground mining, in quarrying, in construction, and in general blasting.

gelatin
 * See: gelatin dynamite. Also spelled gelatine.

gelatin borehole tube
 * A device used in borehole surveying. A tube, containing a compass floating in molten gelatin, is lowered to the point in the borehole at which its verticality is required. It is left in position until the gelatin sets and is then withdrawn. The compass indicates the direction and a small plumb bob shows the angle of dip.

gelatin dynamite
 * A type of highly water-resistant dynamite, characterized by its gelatinous consistency, containing nitroglycerin and nitrocellulose; straight gelatin dynamite is a series of gelatins that include sodium nitrate, while ammonium gelatin dynamites use ammonium nitrate. Syn: ammonia gelatin dynamite; gelatin.

gelatin extras
 * Explosives in which a portion of the nitroglycerin is replaced with ammonium nitrate. The explosive velocity is reduced, but the substantial resistance to water is retained. Less expensive than gelatin dynamites.

gelatins
 * A general term relating to explosives in which a principal constituent, nitroglycerin, is given a gelatinous consistency by mixing it with nitrocotton.

gelation
 * The formation of a gel from a sol, as by coagulation or by precipitation with an electrolyte.

gel cement
 * Cement to which a small percentage of bentonite has been added either dry or mixed with water. Such an addition particularly adapts the slurry for use in cementing casing and recovering lost circulation because it reduces loss of slurry to the formation, makes for a more homogeneous mixture, increases the water-cement ratio, reduces loss of water to the formation, and sets in substantially the same volume as occupied when placed.

gelignite
 * A general term relating to explosives of the gelatin type in which there is a proportion of wood, metal, and oxygen-containing salts.

gelose
 * The colloidal product of plant decay that becomes the principal constituent of coal. See also: carbohumin.

gelosite
 * Constituent of torbanite, consisting of birefringent pale yellow microscopic crushed spheres. CF: humosite. See also: humosite; matrosite; retinosite.

gel strength
 * The ability or the measure of the ability of a colloid to form gels.

gem
 * A cut-and-polished stone that has intrinsic value and possesses the necessary beauty, durability, rarity, and size for use in jewelry as an ornament or for personal adornment; a jewel whose value is not derived from its setting. Syn: cut stone.

gem crystal
 * A crystal from which a gem can be cut.

gem gravel
 * A gravel placer containing an appreciable concentration of gem minerals.

gemmary
 * a. The science of gems. Syn: gemology.

b. A collection of gems; gems considered collectively. c. A house or receptacle for gems and jewels.

gem material
 * Any rough material, either natural or artificial, that can be fashioned into a jewel. CF: gemstone.

gem mineral
 * Any mineral species that yields varieties with sufficient beauty and durability to be classed as gemstones.

Gemolite
 * An illuminator used to observe inclusions and other imperfections in gemstones effectively. Employs either a monocular or a binocular microscope.

gemologist
 * a. One who appraises gems. Also spelled gemmologist (U.K.).

b. One who has mastered gemology.

gemology
 * a. The science of gems. CF: gemmary. Also spelled gemmology (U.K.).

b. The study of fashioned minerals, their imitators and substitutes both natural and synthetic, prized for their beauty and durability. It concerns composition, structure, occurrence, origin, fashioning, and identification of gems, some of which are minerals and some of organic origin, e.g., pearls. CF: descriptive gemology; determinative gemology.

gem pearl
 * a. A term used for those better qualities of fine pearl that possess a rose or other particularly desirable orient. Does not include white pearl.

b. An iridescent pearl, perfectly spherical, with maximum luster of even intensity, free from all visible blemishes, and of a decided and desirable orient, such as pink rose.

gem stick
 * A stick on the end of which a gem is cemented while being cut.

gemstone
 * a. A mineral or petrified material that, when cut and polished, can be used in jewelry. Syn: precious stone.

b. A term that includes pearl, amber, coral, jet, or any stone of any variety of gem material, of sufficient beauty and durability for use as a personal ornament. See also: decorative stone; gem material; ornamental stone. Also spelled gem stone.

gem variety
 * The variety of a mineral species that yields gemstones.

general-crusher foreman
 * In beneficiation, smelting, and refining, one who directs and coordinates all operations concerned with reducing ore to designated size.

general soil survey
 * A general investigation of superficial deposits. The sampling procedure may include augers, boreholes, and trial pits, and tests are made to cover soil identification. This type of survey aims at establishing soil profiles and locating areas requiring special investigation. See also: detailed soil survey; preliminary soil survey.

generation
 * All the crystals of the same mineral species that appear to have crystallized at essentially the same time; e.g., if there are olivine phenocrysts in a groundmass containing olivine, there are said to be two generations of olivine.

generator
 * a. A source of electricity, esp. one that transforms heat or mechanical work directly into electric energy, as opposed to a voltaic battery.

b. A vessel, chamber or machine in which the generation of a gas is effected, as by chemical action.

genesis
 * a. The origin or formation of a natural gem mineral.

b. In petrology, the origin and evolution of rocks based on field and textural observation allied with laboratory analyses and experimental studies. CF: petrogenesis. c. In mineralogy, the origin of stable phases in terms of pressure, temperature, and composition of parent materials. d. In ore deposits, determination of specific peculiar and exceptional conditions under which economic minerals have been concentrated. CF: metallogeny.

genetic classification
 * Any classification based on manner of origin or line of descent. Genetic classifications are set up to deal with fossils, rocks, and minerals.

Geneva ruby
 * An artificial ruby.

Genter filter
 * A filter utilized in coal-washing plants for the recovery of fine coal particles.

Genter thickener
 * Cylindrical tank with obtuse conical base around which raking gear moves slowly, pushing settled sludge to a central discharge. In the body of the tank hang radially mounted tube frames covered with filter cloths (socks). These are connected with a central valve and timing mechanism, so set that vacuum is applied for 1 to 10 min to remove filtrate, after which the gathered solids are displaced by a brief flushback so that they fall to the raking zone.

genthelvite
 * An isometric mineral, Zn (sub 4) Be (sub 3) (SiO (sub 4) ) (sub 3) S ; forms series with danalite and with helvite; in carbonatites and alkaline pegmatites.

genthite
 * See: garnierite.

gently inclined
 * Said of deposits and coal seams with a dip of from 5 degrees to 25 degrees.

genus
 * A category in the hierarchy of plant and animal classification intermediate in rank between family and species. Adj: generic. Plural: genera.