Appendix:Dictionary of Mining, Mineral, and Related Terms/G/2

geo-
 * Prefix from the Greek "ge," meaning land, of the land, or Earth.

geobotanical indicators
 * Some plants develop peculiar diagnostic symptoms that can be interpreted directly in terms of probable excesses of a particular element in the soil. Geobotanical indicators are either plant species or characteristic variations in the growth habits of plant species that are restricted in their distribution to rocks or soils of definite physical or chemical properties. They have been used in locating and mapping ground water, saline deposits, hydrocarbons, and rock types, as well as ores.

geobotanical prospecting
 * a. The visual study of plants, their morphology, and their distribution as indicators of such things as soil composition and depth, bedrock lithology, the possibility of orebodies, and climatic and ground-water conditions. CF: biogeochemical prospecting. See also: botanical anomaly.

b. Prospecting in which visual observation of plants is used as a guide to finding buried ore. Whereas biogeochemical methods require chemical analysis of plant organs, the geobotanical methods depend on direct observations of plant morphology and the distribution of plant species.

geobotany
 * The study of plants as related specif. to their geologic environment.

geocerain
 * See: geocerite.

geocerite
 * A white, flaky, waxlike resin of approximate composition C (sub 27) H (sub 53) O (sub 2) in brown coal. Also spelled geocerain, geocerin. CF: geomyricite.

geochemical anomaly
 * A concentration of one or more elements in rock, soil, sediment, vegetation, or water that is markedly higher or lower than background. The term may also be applied to hydrocarbon concentrations in soils. See also: significant anomaly.

geochemical coherence
 * The phenomenon of the intimate occurring together of certain chemical elements in nature because of their similar chemical properties, as, for example, the group of the lanthanides, zirconium-hafnium, niobium-tantalum, etc.

geochemical cycle
 * The sequence of stages in the migration of elements during geologic changes. Rankama and Sahama distinguish a major or endogenous cycle, proceeding from magma to igneous rocks to sediments to sedimentary rocks to metamorphic rocks and possibly through migmatites back to magma, and a minor or exogenic cycle proceeding from sediments to sedimentary rocks to weathered material and back to sediments again.

geochemical environment
 * Pressure, temperature, and the availability of the most abundant chemical components are the parameters of the geochemical environment that determine which mineral phases are stable. On the basis of these variables, it is possible to classify all the natural geochemical environments of the Earth into two major groups--primary and secondary. The primary environment extends downward from the lower levels of circulating meteoric water to the deepest level of the crust and may extend into the mantle. It is an environment of high temperature and pressure, restricted circulation of fluids, and relatively low free-oxygen content. The secondary environment is the environment of weathering, erosion, and sedimentation at the surface of the Earth. It is characterized by low temperatures, nearly constant low pressure, free movement of solutions, and abundant free oxygen, water, and carbon dioxide.

geochemical exploration
 * The search for economic mineral deposits or petroleum by detection of abnormal concentrations of elements or hydrocarbons in surficial materials or organisms, usually accomplished by instrumental, spot-test, or quickie techniques that may be applied in the field. Syn: geochemical prospecting.

geochemical landscape
 * The pattern, in any given area, in which the net effect of all the dynamic forces concerned in the movement of earth materials will be reflected in the overall pattern of distribution of the elements.

geochemical mapping
 * The systematic collection and processing of a very large number of samples accompanied by the proper presentation and interpretation of the resulting analytical data, usually with reference to a topographic map or other geographic coordinate system.

geochemical prospecting
 * See: geochemical exploration.

geochemical relief
 * A little-used term for the variation in metal values in varied geographic settings. Geochemical contrast.

geochemical survey
 * A survey involving the chemical analysis of systematically collected samples of rock, soil, stream sediments, plants, or water; this expression may be further modified by indicating specif. the material sampled, as, for example, geochemical soil survey.

geochemist
 * An individual who studies the chemistry of earth materials. May be qualified by the term "inorganic" for the study of nonbiological materials, "organic" for the study of plants and hydrocarbons, and "isotope" for the study of nuclides of the elements. Generally, the geochemist is concerned with the distribution of elements in exploration application or with the cycles of elements in basic science.

geochemistry
 * The study of the relative and absolute abundances of the elements and their nuclides (isotopes) in the Earth; the distribution and migration of the individual elements or suites of elements in the various parts of the Earth (the atmosphere, hydrosphere, lithosphere, etc.), and in minerals and rocks, and also the study of principles governing this distribution and migration. Geochemistry may be defined very broadly to include all parts of geology that involve chemical changes, or it may be focused more narrowly on the distribution of the elements, as in Mason's definition; the latter is commonly understood if the term is used without qualification.

geochronic
 * See: geochronologic.

geochronite
 * A monoclinic mineral, Pb (sub 14) (Sb,As) (sub 6) S (sub 23) ; forms a series with jordanite; soft; sp gr, 6.4 to 6.5; associated with galena, jamesonite, and boulangerite; in lead ores in Bolivia, Germany, Sweden, and the United States. Syn: kilbrickenite.

geochronologic
 * Pertaining to geochronology.

geochronologic unit
 * A division of time traditionally distinguished on the basis of the rock record as expressed by a time-stratigraphic unit. Geochronologic units in order of decreasing rank are eon, era, period, epoch, and age. Names of periods and units of lower rank are the same as those of the corresponding time-stratigraphic units; the names of some eras and eons are independently formed. Syn: geologic time unit.

geochronology
 * The study of time in relationship to the history of the Earth, esp. by the absolute age determination and relative dating systems developed for this purpose. See also: absolute time. CF: geochronometry. Syn: geologic chronology.

geochronometry
 * Measurement of geologic time by geochronologic methods, esp. radiometric dating. CF: geochronology.

geochrony
 * An obsolete syn. of geochronology.

geode
 * a. A hollow globular or subspherical body, from 2.5 to 30 cm or more in diameter, found in certain limestone beds and rarely in shales; it is characterized by a thin and sometimes incomplete outermost primary layer of dense chalcedony, by a cavity that is partly filled by a drusy lining of inward-projecting crystals (usually of quartz or calcite and sometimes of barite, celestite, and various sulfides) deposited from solution on the cavity walls. Unlike a druse, a geode is separable (by weathering) as a discrete nodule or concretion from the rock in which it occurs and its inner crystals are not of the same minerals as those of the enclosing rock.

b. The crystal-lined cavity in a geode. c. A term applied to a rock cavity and its lining of crystals that is not separable as a discrete nodule from the enclosing rock. CF: vug.

geodesy
 * a. The science concerned with the determination of the size and shape of the Earth and the precise location of points on its surface.

b. The determination of the gravitational field of the Earth and the study of temporal variations such as Earth tides, polar motion, and rotation of the Earth. Syn: geodetics.

geodetic coordinates
 * Quantities defining the horizontal position of a point on an ellipsoid of reference with respect to a specific geodetic datum, usually expressed as latitude and longitude. These may be referred to as geodetic positions or geographic coordinates. The elevation of a point is also a geodetic coordinate and may be referred to as a height above sea level.

geodetics
 * See: geodesy.

geodetic surveying
 * Surveying in which account is taken of the figure and size of the Earth and corrections are made for Earth curvature; the applied science of geodesy. It is used where the areas or distances involved are so great that results of desired accuracy and precision cannot be obtained by plane surveying.

geodimeter
 * Trade name of an electronic optical device that measures ground distances precisely by electronic timing and phase comparison of modulated light waves that travel from a master unit to a reflector and return to a light-sensitive tube where an electric current is set up. It is normally used at night and is effective with first-order accuracy up to distances of 3 to 25 miles (5 to 40 km). Etymol: acronym for geodetic-distance meter. CF: tellurometer.

geodynamic
 * Pertaining to physical processes within the Earth as they affect the features of the crust.

geognosy
 * An 18th-century term for a science accounting for the origin, distribution, and sequence of minerals and rocks in the Earth's crust. The term was superseded by geology as early ideas were abandoned. It has become restricted to absolute knowledge of the Earth, as distinct from the theoretical and speculative reasoning of geology.

geographical concentration
 * The ratio of face length (X) to length of main haulage roads (L) in the same units; i.e., X/L. See also: concentration of output.

geographic cycle
 * See: cycle of erosion.

Geographic Information System
 * A computer system for managing spatial data. Abbrev. GIS. A GIS, e.g., can provide a simultaneous consideration of geology, geophysics, geochemistry, and mineral deposits in a region for the purposes of mineral exploration.

geography
 * The study of all aspects of the Earth's surface including its natural and political divisions, the distribution and differentiation of areas, and often, people in relationship to their environment.

geohydrology
 * A term, often used interchangeably with hydrogeology, referring to the hydrologic or flow characteristics of subsurface waters.

geoid
 * The figure of the Earth considered as a sea-level surface extended continuously through the continents. It is a theoretically continuous surface that is perpendicular at every point to the direction of gravity (the plumb line). It is the reference for astronomical observations and for geodetic leveling. See also: datum.

geoisotherm
 * See: isogeotherm.

geologic
 * See: geological.

geologic age
 * a. The age of a fossil organism or of a particular geologic event or feature referred to the geologic time scale and expressed in terms either of time units (absolute age) or of comparison with the immediate surroundings (relative age); an age datable by geologic methods.

b. The term is also used to emphasize the long-past periods of time in geologic history, as distinct from present-day or historic times. See also: age.

geological
 * Pertaining to or related to geology. The choice between this term and geologic is optional, and may be made according to the sound of a spoken phrase or sentence. Geological is generally preferred in the names of surveys and societies, and in English and Canadian usage. Syn: geologic.

geological horizon
 * An interface that indicates a particular position in a stratigraphic sequence. In practice it is commonly a very thin bed.

geological province
 * An area throughout which geological history has been essentially the same or one that is characterized by particular structural or physiographic features.

geological section
 * See: geologic section.

geological survey
 * a. A systematic investigation of an area determining the distribution, structure, composition, history, and interrelations of rock units. Its purpose may be either purely scientific or economic with special attention to the distribution, reserves, and potential recovery of mineral resources. Syn: geologic survey.

b. An organization engaged in making surveys; e.g., a state survey or the U.S. Geological Survey.

geologic chronology
 * See: geochronology.

geologic column
 * a. A composite diagram that shows in a single column the subdivisions of part or all of geologic time or the sequence of stratigraphic units of a given locality or region (the oldest at the bottom and the youngest at the top, with dips adjusted to the horizontal) so arranged as to indicate their relations to the subdivisions of geologic time and their relative positions to each other. See also: columnar section.

b. The vertical or chronologic arrangement or sequence of rock units portrayed in a geologic column. See also: geologic section.

geologic drilling
 * Drilling done primarily to obtain information from which the geology of the formations penetrated can be determined.

geologic engineering
 * See: engineering geology.

geologic formation
 * See: formation.

geologic log
 * A written and/or graphic record of the geologic data obtained from drillhole core and/or cuttings. In noncore drilling, the cuttings are separated at depth intervals of about 1 m or 2 m and examined. In core drilling, the core is kept in sequence and examined. The essential description of core includes lithology, alteration, mineralization, and structural discontinuities. CF: geotechnical log.

geologic map
 * A map on which is recorded geologic information, such as the distribution, nature, and age relationships of rock units (surficial deposits may or may not be mapped separately), and the occurrence of structural features (folds, faults, joints), mineral deposits, and fossil localities. It may indicate geologic structure by means of formational outcrop patterns, by conventional symbols giving the direction and amount of dip at certain points, or by structure-contour lines.

geologic mineralizer
 * Substance that promotes mineral concentration and crystallization during solidification of rock-forming material, particularly in pegmatite dikes. Syn: ore-forming fluid; mineralizer.

geologic section
 * Any sequence of rock units found in a given region either at the surface or below it (as in a drilled well or mine shaft); a local geologic column. Syn: geological section; stratigraphic section. See also: geologic column.

geologic survey
 * See: geological survey.

geologic thermometer
 * See: geothermometer.

geologic time
 * The period of time dealt with by historical geology, or the time extending from the end of the formative period of the Earth as a separate planetary body to the beginning of written or human history; the part of the Earth's history that is represented by and recorded in the succession of rocks. The term implies extremely long duration of remoteness in the past, although no precise limits can be set.

geologic time scale
 * An arbitrary chronologic arrangement or sequence of geologic events, used as a measure of the relative or absolute duration or age of any part of geologic time, and usually presented in the form of a chart showing the names of the various rock-stratigraphic, time-stratigraphic, or geologic-time units, as currently understood; e.g., the geologic time scales published by Harland et al. (1982), Odin (1982), Palmer (1983), and Salvador (1985). Syn: time scale.

geologic time unit
 * The time unit corresponding with a time-stratigraphic unit; e.g., period, epoch, or age. See also: geochronologic unit.

geologist
 * One who is trained in and works in any of the geological sciences.

geologize
 * To participate in or talk about geology; to practice geology.

geology
 * The study of the planet Earth--the materials of which it is made, the processes that act on these materials, the products formed, and the history of the planet and its life forms since its origin. Geology considers the physical forces that act on the Earth, the chemistry of its constituent materials, and the biology of its past inhabitants as revealed by fossils. Clues on the origin of the planet are sought in a study of the Moon and other extraterrestrial bodies. The knowledge thus obtained is placed in the service of humans--to aid in discovery of minerals and fuels of value in the Earth's crust, to identify geologically stable sites for major structures, and to provide foreknowledge of some of the dangers associated with the mobile forces of a dynamic Earth. See also: historical geology; physical geology.

geology system
 * a. The formal chronostratigraphic unit of rank next lower than "erathem" and above "series". Rocks encompassed by a system represent a time span and an episode of Earth history sufficiently great to serve as a worldwide reference unit. The temporal equivalent of a system is a "period." The system is the fundamental unit of chronostratigraphic classification of Phanerozoic rocks, extended from a type area or region and correlated mainly by its fossil content. System boundaries either have been ratified by the International Union of Geological Sciences or are under review by a working group of the International Commission on Stratigraphy. The Proterozoic systems are related to geologic events with geochronologic boundaries established by the Subcommission on Precambrian Stratigraphy.

b. Some systems initially established in Europe were later divided or grouped elsewhere into units ranked as systems, but these are more appropriately known as "subsystems" or "supersystems".

geomagnetician
 * One who sets up magnetic observatories and stations in order to chart the Earth's magnetic field and applies data obtained to problems in the fields of telephony, telegraphy, radio broadcasting, navigation, mapping, and geophysical prospecting. Also called terrestrial magnetician.

geomagnetic meridian
 * See: magnetic meridian.

geomorphic
 * a. Pertaining to the form of the Earth or of its surface features; e.g., a geomorphic province.

b. Pertaining to geomorphology; geomorphologic.

geomorphic cycle
 * See: cycle of erosion.

geomorphogeny
 * That part of geomorphology that deals with the origin, development, and changes of the Earth's surface features or landforms.

geomorphology
 * a. The science that treats the general configuration of the Earth's surface; specif., the study of the classification, description, nature, origin, and development of present landforms and their relationships to underlying structures, and of the history of geologic changes as recorded by these surface features. In the United States, it has come to replace the term "physiography" and is usually considered a branch of geology; in Great Britain, it is usually regarded as a branch of geography.

b. Strictly, any study that deals with the form of the Earth (including geodesy, and structural and dynamic geology). This usage is more common in Europe, where the term has even been applied broadly to the science of the Earth. c. The features dealt with in, or a treatise on, geomorphology; e.g., the geomorphology of Texas.

geomyricin
 * See: geomyricite.

geomyricite
 * A white, waxy resin of approximate composition C (sub 32) H (sub 62) O (sub 2) in brown coal. Syn: geomyricin. CF: geocerite.

geophone
 * A seismic detector that produces a voltage proportional to the displacement, velocity, or acceleration of ground motion, within a limited frequency range. Syn: jug; seismometer; pickup. CF: seismograph; transducer.

geophysical exploration
 * Exploring for minerals or mineral fuels, or determining the nature of Earth materials by measuring a physical property of the rocks and interpreting the results in terms of geologic features or the economic deposits sought. Physical measurements may be taken on the surface, in boreholes, or from airborne or satellite platforms. See also: geophysical prospecting.

geophysical log
 * See: well log.

geophysical prospecting
 * Exploring for minerals or mineral fuels, or determining the nature of earth materials by measuring a physical property of the rocks, and interpreting the results in terms of geologic features or the economic deposits sought. Physical measurements may be taken on the surface, in boreholes, or from airborne or satellite platforms. See also: geophysical exploration.

geophysical prospecting surveyor
 * Person who locates and marks sites selected for conducting geophysical prospecting activities concerned with locating subsurface earth formations likely to contain petroleum or mineral deposits.

geophysical survey
 * The exploration of an area in which geophysical properties and relationships unique to the area are mapped by one or more geophysical methods.

geophysicist
 * One who studies seismic, gravitational, electrical, thermal, radiometric, and/or magnetic phenomena to investigate geological phenomena, such as structure and composition of the Earth, forces causing movement and warping of surface, origin and activity of glaciers and volcanoes, and the location and cause of earthquakes; charts ocean currents and tides; takes measurements concerning shape and movements of Earth, and acoustic, optical, and electrical phenomena in the atmosphere; and locates petroleum and mineral deposits.

geophysics
 * A branch of physics dealing with the Earth, including its atmosphere and hydrosphere. It includes the use of seismic, gravitational, electrical, thermal, radiometric, and magnetic phenomena to elucidate processes of dynamical geology and physical geography, and makes use of geodesy, geology, seismology, meteorology, oceanography, magnetism, and other Earth sciences in collecting and interpreting Earth data. Geophysical methods have been applied successfully to the identification of underground structures in the Earth and to the search for structures of a particular type, as, for example, those associated with oil-bearing sands.

georgiadesite
 * A monoclinic mineral, Pb (sub 16) (AsO (sub 4) ) (sub 4) Cl (sub 14) (OH) (sub 6) or Pb (sub 16) (AsO (sub 4) ) (sub 4) Cl (sub 14) O (sub 2) (OH) (sub 2) ; forms stubby tablets; sp gr, 7.1; associated with laurionite, matlockite, and fiedlerite on altered slags at Laurium, Greece.

geosphere
 * The solid portion of the Earth, including water masses; the lithosphere plus the hydrosphere. Above the geosphere lies the atmosphere, and at the interface between these two regions is found almost all of the biosphere, or zone of life.

geostatic pressure
 * See: rock pressure.

geostatistics
 * A methodology for the analysis of spatially correlated data. The characteristic feature is the use of variograms or related techniques to quantify and model the spatial correlation structure. Also includes the various techniques such as kriging, which utilize spatial correlation models.

geosyncline
 * A mobile downwarping of the crust of the Earth, either elongate or basinlike, measured in scores of kilometers, in which sedimentary and volcanic rocks accumulate to thicknesses of thousands of meters. A geosyncline may form in part of a tectonic cycle, in which orogeny follows. Recognition of the plate structure of the lithosphere has led to appreciation that nearly all geosynclinal phenomena are related to ocean opening and closing. CF: mobile belt. See also: synclinorium. Ant: geanticline.

geotechnical log
 * A written and/or graphic record of the data obtained from drillhole core. In addition to the data given in geologic logs, geotechnical logs require more detail on discontinuities such as fractures, joints, bedding, rock quality designation, and hydrologic conditions. CF: geologic log.

geotechnics
 * The application of scientific methods and engineering principles to the acquisition, interpretation, and use of knowledge of materials of the Earth's crust for the solution of engineering problems; the applied science of making the Earth more habitable. It embraces the fields of soil mechanics and rock mechanics, and many of the engineering aspects of geology, geophysics, hydrology, and related sciences. Syn: geotechnique.

geotechnique
 * See: geotechnics.

geotechnology
 * The application of scientific methods and engineering techniques to the exploitation and use of natural resources.

geotectonic
 * See: tectonic.

geotectonics
 * See: tectonics.

geotherm
 * See: isogeotherm.

geothermal
 * Pertaining to the heat of the interior of the Earth. Syn: geothermic.

geothermal gradient
 * The rate of increase of temperature in the Earth with depth. The gradient differs from place to place depending on the heat flow in the region and the thermal conductivity of the rocks. The average geothermal gradient in the Earth's crust approximates 25 degrees C per kilometer of depth.

geothermic
 * See: geothermal.

geothermic gradient
 * See: strata temperature.

geothermometer
 * An indicator of the temperature at which some reaction took place or some geologic process was active. Syn: geologic thermometer.

geotomography
 * The adaptation of computer aided tomography (CAT) scan technology to tomographic analysis of geologic features such as fractures and differing rock types. In geotomography, the software analyzes the energy ray paths between a transmitter and receiver that are placed in separate drill holes, at various locations along a single drill hole, or along an underground opening. Various types of energy waves, such as seismic, acoustic, electromagnetic, or X-rays, can be analyzed by the computer software to create an image.

gerasimovskite
 * An amorphous mineral, (Mn,Ca) (sub 2) (Nb,Ti) (sub 5) O (sub 12) .9H (sub 2) O(?) ; forms a series with manganbelyankinite; soft; in ussingite pegmatites in the Lovozero massif, Kola Peninsula, Russia.

gerhardite
 * A basic copper nitrate containing 52.9% copper. Crystallization, orthorhombic. Cleavage, yields flexible laminae. Tenacity, fragile, and sectile. Mohs hardness, 2; sp gr, 3.426; luster, vitreous, brilliant; color, deep emerald-green; streak, light green; transparent; soluble in dilute acids. From Jerome, AZ.

gerhardtite
 * An orthorhombic mineral, Cu (sub 2) (NO (sub 3) )(OH) (sub 3) ; dark to emerald green; soft; occurs with atacamite, brochantite, malachite, and azurite in oxidized zones of copper deposits in arid and semiarid regions.

german
 * A straw tube filled with gunpowder and used as a fuse. Not used in coal mines.

germanate-pyromorphite
 * Synthetic Pb (sub 5) (GeO (sub 4) ) (sub 3) Cl ; forms apatite structure.

German cupellation
 * A method of cupellation using a large reverberatory furnace with a fixed bed and a movable roof. The bullion to be cupelled is all charged at once, and the silver is not refined in the same furnace where the cupellation is carried on.

German cut
 * See: pyramid cut.

German gold
 * Archaic name for amber.

germanite
 * An isometric mineral, Cu (sub 26) Fe (sub 4) Ge (sub 4) S (sub 32) ; associated with tennantite, sphalerite, enargite, pyrite, and bornite; at the Tsumeb Mine in Namibia.

germanium
 * A grayish-white, metallic element occurring in argyrodite, a sulfide of germanium and silver; and in germanite, zinc ores, and coal. Its presence in coal ensures a large reserve of the element in the future. Symbol, Ge. It is a very important semiconductor material. Also used as an alloying agent, a phosphor, a catalyst, and for infrared detectors and optical equipment.

germanium dioxide (soluble)
 * GeO (sub 2) ; melting point, 1,115 degrees C. This oxide is a glass former and provides some unique properties; e.g., greater dispersion, lower melting temperature, and higher transmissivity for infrared radiation. Some germanium oxide complexes and solid solutions have ferroelectric properties. Colorless; sp gr, 4.228 (at 25 degrees C); hexagonal; soluble in alkalies; and slightly soluble in acids and in water. Used as an ingredient of special glass mixtures.

germanium nitride
 * Ge (sub 3) N (sub 4) ; decomposes at 800 degrees C. A special electroceramic of high resistivity.

German lapis
 * See: false lapis.

German reduction process
 * This process consists in (1) roasting copper ore, (2) melting and obtaining a matte with 30% to 40% copper called coarse metal, (3) roasting the coarse metal, (4) melting and obtaining a matte with 60% to 70% copper called fine metal, (5) roasting the fine metal, and (6) melting and obtaining black copper.

German steel
 * A metal made from charcoal iron obtained from bog iron or from sparry carbonate of iron.

gersdorffite
 * An isometric mineral, NiAsS ; cobaltite group; massive; sp gr, 5.9 to 6.0; in sulfide veins intergrown with maucherite, nickeline, and chalcopyrite at the Garson and Falconbridge Mines, Sudbury, ON, Can.; with cobaltite and rammelsbergite in the silver-arsenide ores of Cobalt, ON, Can.; a source of nickel.

Gerstenhofer furnace
 * A shaft furnace, filled with terraces or shelves, through which crushed ore is caused to fall for roasting.

gerstleyite
 * A monoclinic mineral, Na (sub 2) (Sb,As) (sub 8) S (sub 13) .2H (sub 2) O; dark red; soft; in fine granular aggregates, groups of small plates, or spherules in clay, with borates at the Baker Mine, Kramer district, Kern County, CA.

get cleanup
 * Arkansas. To have an opportunity to load out all the coal a miner has loosened.

getter
 * Substance used to combine with the residual oxygen in an electric bulb or tube. Its use is called gettering.

getting
 * The actual process of digging clay, by hand or by excavator; getting and transporting form the successive stages of winning.

geversite
 * An isometric mineral, Pt(Sb,Bi) (sub 2) ; pyrite group; forms tiny grains intergrown with native platinum in concentrates at the Dreikop Mine, eastern Transvaal, Republic of South Africa.

geyerite
 * See: loellingite.

geyser basin
 * A valley or other area that contains numerous springs, geysers, and steaming fissures fed by the same ground-water flow.

geyserite
 * Syn: siliceous sinter. Used esp. for the compact, loose, concretionary, scaly, or filamentous incrustation of opaline silica deposited by precipitation from the waters of a geyser.

ghost crystal
 * See: phantom crystal.

ghost reflection
 * In the seismic reflection method, a special type of multiple reflection. This is the reflection that takes place when the energy traveling upward from the shot is reflected downward by the base of the weathered zone or by the Earth's surface. The reflected pulse follows the primary downgoing pulse by a time interval determined by the depth of the shot below the weathering (or the free surface) and the velocity of the material above the shot. For normal shooting depths this interval will range from 0.010 to 0.020 s.

giant
 * The nozzle of a pipe used to convey water for hydraulic mining and for the purpose of distributing or properly applying and increasing the force of the water. See also: hydraulic monitor.

giant granite
 * See: pegmatite.

giant powder
 * a. A blasting powder consisting of nitroglycerin, sodium nitrate, sulfur, rosin, and sometimes kieselguhr.

b. Nitroglycerin absorbed by an inert filler such as kieselguhr.

giant tender
 * See: nozzleman.

gib
 * a. A temporary support at the face to prevent coal from falling before the cut is complete.

b. Scot. A sprag; a prop put in the holing of a seam while being undercut.

gibber
 * An Australian term for a pebble or boulder; esp. one of the wind-polished or wind-sculptured stones that compose a desert pavement or the lag gravels of an arid region. It is pronounced with a hard g.

Gibbs adsorption theorem
 * A solute that lowers the surface tension of its solvent tends to concentrate at the air-liquid interphase, and vice versa.

gibbsite
 * A monoclinic mineral, 8[Al(OH) (sub 3) ] ; pisolitic; in micalike crystals, or stalactitic and spheroidal forms; a constituent of bauxite associated with boehmite and/or diaspore; formed by weathering of igneous rocks, esp. nepheline syenite; also in veins; a source of aluminum and synthetic abrasives. In emery deposits formed by thermal or regional metamorphism of bauxites, gibbsite occurs as an alteration crust on corundum. Syn: hydrargillite.

Gibbs phase rule
 * See: phase rule.

Gibraltar stone
 * A light-colored onyx at Gibraltar. See also: Mexican onyx.

gieseckite
 * a. An aluminosilicate of magnesium and potassium, sometimes with appreciable FeO.

b. Green fine-grained micaceous alteration of nepheline.

giessenite
 * An orthorhombic mineral, Pb (sub 13) (Cu,Ag)(Bi,Sb) (sub 9) S (sub 28) (?); forms soft, metallic, needles on galena associated with pyrite, rutile, and tennantite; near Giessen in the Binn valley, Valais, Switzerland.

gig
 * a. A mine cage or skip.

b. Gravity or self-acting haulage. Also called ginney.

Gilbert
 * The unit of magnetomotive force in the electromagnetic system, equal to the magnetomotive force of a closed loop of one turn in which there is a current of 1/(4pi ) abamp.

gild
 * To wash over or overlay thinly with gold; coat with gold, either in leaf or powder, or by electroplating; as, to gild a chandelier. To overlay with any other substance for the purpose of giving the appearance of gold.

gillespite
 * A tetragonal mineral, BaFeSi (sub 4) O (sub 10) ; vitreous; red; translucent; associated with sanbornite, celsian, taramellite, and witherite at Dry Delta, AK, and Fresno and Mariposa Counties, CA.

Gilman heat-treating machine
 * Used for tempering and hardening of drill bits at the mine. Syn: automatic heat-treating machine.

gilsonite
 * See: uintaite.

gim peg
 * A device used in faceting gems; a piece of wood containing a series of holes into which a dop stick (gem stick) can be fixed at various angles, thus regulating the angle of the facet being cut. Syn: jamb stick.

gin
 * a. A pump worked by a windlass.

b. A pile-driving machine. c. A drum framework and pulleys for hoisting mineral from a shallow shaft. d. Horse gear for hoisting through a mine shaft. e. A small, hand-cranked hoist. f. Eng. A drum and framework carrying pulleys, by which the ore and waste are raised from a shallow pit; a whim. Also called horse gin. A contraction of engine. g. An old form of hoisting engine.

ginging
 * The process of lining a shaft with bricks or masonry; the lining itself.

ginney
 * A journey set or train of tubs, trams, or trucks, or a self-acting incline, in a coal mine.

ginney tender
 * A person working on an endless chain haulage.

ginny carriage
 * Eng. A small railway truck for transporting constructive materials.

ginorite
 * A monoclinic mineral, Ca (sub 2) B (sub 14) O (sub 23) .8H (sub 2) O ; transparent to translucent; occurs as pellets embedded in a matrix of sassolite and clay within colemanite-veined basalt at Death Valley, CA; also as minute lozenge-shaped plates aggregated into masses with calcite in veins in sandstone at Sasso Pisano, Tuscany, Italy. CF: strontioginorite.

gin pit
 * A shallow mine, the hoisting from which is done by a gin.

gin race
 * The circular path that a gin horse travels. Syn: gin ring.

gin ring
 * See: gin race.

gin wheel
 * The cylinder of a gin or winch.

giobertite
 * See: magnesite.

gips plate
 * See: gypsum plate; accessory plate.

giraffe
 * a. A cagelike mine car esp. adapted for inclines, having the frame higher at one end than at the other.

b. A mechanical appliance for receiving and tripping a car of ore, etc., when it arrives at the surface. c. A multiple-deck skip.

girasol
 * a. A name applied to many gemstones with a girasol effect, e.g., moonstone; specif. a translucent variety of "fire opal" with reddish reflections in bright light and a faint bluish-white floating light emanating from the center of the stone.

b. adj. Said of any gem variety, e.g., sapphire, chrysoberyl, that exhibits a billowy, gleaming round or elongated area of light that "floats" or moves about as the stone is turned or as the light source is moved. c. A name for glass spheres used in the manufacture of imitation pearls.

girdle
 * a. A thin sandstone stratum.

b. Flattened lenticles or nodules of any hard stone in softer beds. Sometimes extended also to beds. c. In stratigraphy: (1) a thin stratum, particularly said of sandstone or coal, esp. when exposed in a shaft or borehole or (2) flattened lenticles or nodules of any hard stone in softer beds. d. In gemology, the line that encompasses a cut gem parallel to the horizon; or that determines the greatest horizontal expansion of the stone. e. In structural petrology, on an equal-area projection, a belt or concentration of points representing orientations of fabric elements. If this belt coincides approx. with a great circle of the projection, it is referred to as a great-circle girdle. If the belt of concentration coincides approx. with a small circle of the projection, it is called a small-circle or "cleft girdle"

Girond process
 * In this process, fluorspar, soda ash, carbon, lime, and mill scale were thrown on to the bottom of a hot ladle, and thus sintered. On tapping the steel from the open hearth furnace into the ladle, the resulting boil removed part of the phosphorus.

girth
 * a. A brace member running horizontally between the legs of a drill tripod or derrick.

b. In square-set timbering, a horizontal brace running parallel to the drift.

GIS
 * See: Geographic Information System.

Gish-Rooney method
 * An artificial-current conductive direct-current method of measuring ground resistivity which avoids polarization by continually reversing the current with a set of commutators.

gismondine
 * A monoclinic mineral, Ca (sub 2) Al (sub 4) Si (sub 4) O (sub 16) .9H (sub 2) O ; zeolite group; pseudotetragonal; vitreous, transparent to translucent; in cavities in leucitic tephrites and related lavas; also zeolite zones in basaltic lavas where it is associated with chabazite, thomsonite, and phillipsite. Also spelled gismondite.

Gjer's soaking pit
 * A cavity lined with refractory material used in metal working to enclose large ingots, in order to preserve them at a high temperature, and thus avoid the necessity of reheating.

glacial
 * a. Of or relating to the presence and activities of ice or glaciers, as glacial erosion.

b. Pertaining to distinctive features and materials produced by or derived from glaciers and ice sheets, as glacial lakes. c. Pertaining to an ice age or region of glaciation. d. Suggestive of the extremely slow movement of glaciers. e. Used loosely as descriptive or suggestive of ice, or of below-freezing temperature.

glacial action
 * All processes due to the agency of glacier ice, such as erosion, transportation, and deposition. The term sometimes includes the action of meltwater streams derived from the ice. See also: glacial erosion.

glacial deposits
 * See: glacial drift.

glacial drift
 * Boulders, till, gravel, sand, or clay transported and deposited by a glacier or its meltwater. See also: glacial overburden; drift. Syn: glacial deposits.

glacial epoch
 * Any part of geologic time, from Precambrian onward, in which the climate was notably cold in both the Northern and Southern Hemispheres, and widespread glaciers moved toward the equator and covered a much larger total area than those of the present day; specif. the latest of the glacial epochs, known as the Pleistocene Epoch. Syn: glacial period; drift epoch.

glacial erosion
 * The grinding, scouring, plucking, gouging, grooving, scratching, and polishing effected by the movement of glacier ice armed with rock fragments frozen into it, together with the erosive action of meltwater streams. See also: glacial action.

Glacialite
 * Trade name for a white clay from Enid, OK., marketed as a fuller's earth.

glacial overburden
 * Glacial-drift materials overlying bedrock. See also: glacial drift.

glacial period
 * See: glacial epoch.

glacial soil
 * Soil composed of boulder clays, moraines, etc., which were formed by the action of ice during the Pleistocene age.

glacial till
 * See: till.

glaciated
 * Said of a formerly glacier-covered land surface, esp. one that has been modified by the action of a glacier or an ice sheet, as a glaciated rock knob.

glaciation
 * a. The formation, movement, and recession of glaciers or ice sheets.

b. The covering of large land areas by glaciers or ice sheets. c. The geographic distribution of glaciers and ice sheets. d. A collective term for the geologic processes of glacial activity, including erosion and deposition, and the resulting effects of such action on the Earth's surface. e. Any of several minor parts of geologic time during which glaciers were more extensive than at present; a glacial epoch, or a glacial stage.

glacier
 * A large mass of ice formed, at least in part, on land by the compaction and recrystallization of snow, moving slowly by creep downslope or outward in all directions due to the stress of its own weight, and surviving from year to year. Included are small mountain glaciers as well as ice sheets continental in size, and ice shelves that float on the ocean but are fed in part by ice formed on land.

glacier theory
 * The theory, first propounded about 1840 and now universally accepted, that the drift was deposited through the agency of glaciers and ice sheets moving slowly from higher to lower latitudes during the Pleistocene Epoch.

glaciofluvial
 * Pertaining to the meltwater streams flowing from wasting glacier ice and esp. to the deposits and landforms produced by such streams, as kame terraces and outwash plains; relating to the combined action of glaciers and streams. Syn: fluvioglacial.

glaciolacustrine
 * Pertaining to, derived from, or deposited in glacial lakes; esp. said of the deposits and landforms composed of suspended material brought by meltwater streams flowing into lakes bordering the glacier, such as deltas, kame deltas, and varved sediments.

glaciology
 * a. The study of all aspects of snow and ice; the science that treats quantitatively the whole range of processes associated with all forms of solid existing water. Syn: cryology.

b. The study of existing glaciers and ice sheets, and of their physical properties. This definition is not internationally accepted.

glaciomarine
 * Of, or relating to, processes or deposits that involve the action of glaciers and the sea, or the action of glaciers in the sea.

gladite
 * An orthorhombic mineral, PbCuBi (sub 5) S (sub 9) ; occurs in soft, metallic prismatic crystals; sp gr, 6.96; in lead-zinc ores at Gladhammar, Kalmar, Sweden.

glady
 * a. A term used in Devon, England, for a variegated black and white clay having a slippery or smooth texture and often associated with stoneware clays. Also spelled: gladii.

b. Said of a limestone-outcrop area having shallow soil.

glance
 * a. A mineral having a splendant luster, e.g., chalcocite (copper glance).

b. Any of several sulfide minerals that are mostly dark colored, having a metallic luster. Syn: lead sulfide.

gland
 * a. The outer portion of a stuffing box, having a tubular projection embracing the rod, extending into the bore of the box, and bearing against the packing.

b. The fixed engaging part of a positive-driven clutch.

glare
 * a. A visual sensation that can result in annoyance, discomfort, loss in visual performance, or reduction of visibilty. There are three types of glare: disability, discomfort, and reflected. Glare is a significant factor in determining the design of underground coal mine illumination systems.

b. See also: disability glare; discomfort glare.

glass
 * a. A state of matter intermediate between the close-packed, highly ordered array of a crystal and the poorly packed, highly disordered array of a gas. Most glasses are supercooled liquids, i.e., are metastable, but there is no true break in the change in properties between the metastable and stable states. The distinction between glass and liquid is made solely on the basis of viscosity, and is not necessarily related, except indirectly, to the difference between metastable and stable states.

b. An amorphous product of the rapid cooling of a magma. It may constitute the whole rock (e.g., obsidian) or only part of a groundmass. CF: volcanic glass.

glass-cloth screens
 * A device of clothlike material woven from glass fibers that is attached to a metal frame to form a box- or basin-shaped receptacle, for filtering out impurities from the incoming stream of molten aluminum before the metal reaches the molds.

glass electrode
 * A glass-membrane electrode used to measure pH or hydrogen-ion activity.

glass enclosure
 * See: gas bubble.

glassies
 * Octahedral diamond crystals (transparent).

glass meteorite
 * See: moldavite.

glass opal
 * See: hyalite.

glass porphyry
 * See: vitrophyre.

glass sand
 * A sand that is suitable for glassmaking because of its high silica content (93% to 99%) and its low content of iron oxide, chromium, cobalt, and other colorants.

glass schorl
 * See: axinite.

glass wool
 * See: mineral wool.

glassy feldspar
 * Two varieties of potassium feldspar occur as transparent colorless crystals, sanidine and adularia; also transparent yellow orthoclase and transparent colorless albite. Syn: sanidine.

glauberite
 * A monoclinic mineral, Na (sub 2) Ca(SO (sub 4) ) (sub 2) ; slightly salty tasting; in evaporite deposits and fumarolic crusts; a source of sodium sulfate.

Glauber salt
 * See: mirabilite. Also spelled Glauber's salt.

glaucocerinite
 * A hexagonal mineral, (Zn,Cu) (sub 10) Al (sub 6) (SO (sub 4) ) (sub 3) (OH) (sub 32) .18H (sub 2) O ; forms soft, blue, fibrous-botryoidal coating on adamite; associated with malachite, smithsonite, and gypsum at Laurium, Greece.

glaucochroite
 * An orthorhombic mineral, CaMnSiO (sub 4) ; occurs in prismatic crystals associated with nasonite, willemite, garnet, axinite, and barite at Franklin, NJ. CF: monticellite.

glaucodot
 * An orthorhombic mineral, (Co,Fe)AsS ; pseudocubic, dimorphous with alloclasite; in metallic prismatic crystals, or massive in cobalt ores with cobaltite and pyrite. Also spelled glaukodot.

glaucolite
 * A blue or green variety of scapolite.

glauconite
 * a. A monoclinic mineral, 4[(K,Na)(Fe (super 3+) ,Al,Mg) (sub 2) (Si,Al) (sub 4) O (sub 10) (OH) (sub 2) ] ; mica group; basal cleavage; dull, light to dark green; soft; a common authigenic mineral in marine sediments, useful for radiometric ages for host rocks. Syn: greensand.

b. A general term applied to green hydrous silicates of potassium and iron. CF: celadonite.

glauconitic sandstone
 * A sandstone containing sufficient grains of glauconite to impart a marked greenish color to the rock; greensand.

glaucophane
 * A monoclinic mineral, 2[Na (sub 2) (Mg,Fe) (sub 3) Al (sub 2) Si (sub 8) O (sub 22) (OH) (sub 2) ] ; amphibole group with Mg/(Mg+Fe) = 0.5 to 1.0; prismatic cleavage; bluish-gray to lavender blue; common in low-temperature, high-pressure schists associated with lawsonite, pumpellyite, or epidote. CF: crossite; riebeckite.

glaucophane schist
 * A type of amphibole schist in which glaucophane rather than hornblende is an abundant mineral. Epidote frequently occurs, and there are quartz and mica varieties.

glaucopyrite
 * A variety of loellingite containing cobalt. See also: loellingite.

glazing barrel
 * A rotating barrel in which gunpowder is glazed with graphite.

glebe
 * a. A tract of land containing mineral deposits or ore.

b. Obsolete term for a clod of earth, an ore, or an earthy mineral.

Gleeds
 * A glowing coal or small coke such as that used in nailmaking.

gleet
 * Slime, ooze, slimy alluvial deposit. Also spelled glet.

glessite
 * A brown variety of retinite; sp gr, 1.015 to 1.027; found on the shores of the Baltic Sea.

gley soil
 * Soil developed under conditions of poor drainage, resulting in reduction of iron and other elements and in gray colors and mottles. The term is obsolete in the United States.

glide
 * a. See: slip.

b. A noncrystallographic shearing movement, as one grain over another. c. See: glide reflection.

glide direction
 * a. The direction of gliding along glide planes in a mineral.

b. The crystallographic direction of translation along a glide plane in a space group; may be parallel to a crystallographic axis or along a diagonal. c. The crystallographic direction of slip along a slip plane in a single crystal during plastic deformation. Syn: slip direction. CF: slip.

glide plane
 * a. In single-crystal deformation, a plane on which translation- or twin-gliding takes place without rupture during plastic deformation. Syn: slip plane. CF: slip.

b. The common plane of the two axes of a twin crystal. c. Slip plane or parting of mineral specimen. Direction along which slip may occur under suitably directed pressure; due to weakness of bond in crystalline structure along one of the three axes.

glide reflection
 * See: glide.

gliding
 * a. A change of form by differential movements along definite planes in crystals without fracture.

b. The formation of twin crystals. c. See: slip.

gliding plane
 * See: slip plane.

glimmer
 * See: mica.

glimmerite
 * See: biotitite.

glimmer plate
 * See: mica plate; accessory plate.

glimmerton
 * An early name for illite. Syn: illite.

glinite
 * A group name for clay minerals from clay deposits. See also: chasovrite.

glist
 * a. A gleam; sparkle.

b. Eng. A dark, shining mineral resembling black tourmaline. c. An early name for mica (Cornish).

glistening
 * As applied to the degree of luster of a mineral, means those minerals affording a general reflection from the surface, but no image, as talc or chalcopyrite.

Global Positioning System
 * A satellite-based navigational system permitting the determination of any point on the Earth with high accuracy. Abbrev: GPS. GPS is used in mapping, mineral exploration, and GIS data collection. The systems depend on the Navigation Satellite Timing and Ranging (NAVSTAR) GPS developed and operated by the U.S. Department of Defense, which consists of a network of 25 satellites in orbit about the Earth as well as ground operations support. After all the satellites are deployed, GPS will provide all-weather, worldwide, two- and three-dimensional (latitude, longitude, and elevation) positioning capabilities over a 24-h period.

globe thermometer
 * A thermometer in a hollow spherical black globe, the readings from which show a higher value, due to radiation, than those from a conventional thermometer so that the globe device measures the effectual radiation temperature.

globigerina ooze
 * A widespread, deep-sea deposit largely composed of the shells of foraminifera, among which Globigerina is esp. abundant. Other calcareous remains are present (about 10%), together with an inorganic residue (about 3% or 4%) having the composition of red clay.

globular
 * See: spherulitic.

globular powder
 * Particles having approx. spherical shape.

globulite
 * A tiny, spherical, incipient crystal visible in some volcanic glasses examined in thin section under a polarized-light microscope.

glockerite
 * A cryptocrystalline variety of lepidocrocite; formed by oxidation of iron sulfides as pale yellow to black crusts, stalactites, or earthy masses. Syn: vitriol ocher.

glomerocryst
 * Distinct clusters of megascopic crystals as in a glomerophorphyritic rock. See also: polycrystal.

glomeroporphyritic
 * See: cumulophyric.

glomeroporphyry
 * A porphyry in which the phenocrysts are gathered in distinct clusters.

gloom
 * A stove for drying gunpowder; drying oven.

glory hole
 * a. A funnel-shaped excavation, the bottom of which is connected to a raise driven from an underground haulage level. The ore is broken by drilling and blasting in benches around the periphery of the funnel. This process is also called milling, and the excavation is termed a mill hole or simply a mill.

b. A vertical pit, material from which is fed by gravity to hauling units in a shaft under the pit bottom. c. A combination opencast and underground mining system, in which quarried material gravitates or is moved to a short shaft, from the bottom of which it is delivered to an underground transport system. d. Can. Large open-pit excavation. e. An opening through which to observe the interior of a furnace.

glory-hole system
 * A method of mining using a system of haulageways beneath the block of ore, which has had its top surface exposed by the removal of the overburden. Over the haulageways are chutes that extend up to the surface, and are spaced at intervals of 50 ft (15.2 m) or at any other convenient distance. The excavation of the ore begins at the top of the chute, and broken ore is removed by loading it out from the chutes into cars on the haulage level. The ore block is worked from the top down. The method is similar in principle to underhand stoping. Also called milling system; chute system.

Glover's tower
 * In sulfuric acid works, a tower through which the acid from the Gay-Lussac tower trickles and yields nitrous anhydride to the gases entering the lead chambers, at the same time cooling them. CF: Gay-Lussac's tower.

glow
 * a. The incandescence of a heated substance, or the light from such a substance; white or red heat.

b. The light from a phosphorescent mineral.

glucine
 * CaBe (sub 4) (PO (sub 4) ) (sub 2) (OH) (sub 4) .1/2H (sub 2) O, massive and encrusting, with moraesite from a locality in the Urals. Named from the alternative of beryllium-glucinum.

glushinskite
 * A monoclinic mineral, Mg(C (sub 2) O (sub 4) ).2H (sub 2) O ; forms on serpentinite as a reaction between oxalic acid from the lichen Lecanora atra and magnesium-rich serpentine minerals; in northeast Scotland.

glycerol
 * Clear; colorless or pale yellow; syrupy liquid; CH (sub 2) OHCHOHCH (sub 2) OH . Used in explosives, as a binder for cements and mixes, and as a lubricant and a softener; used in the manufacture of munitions and as an antifreeze liquid.

glycerol trinitrate
 * See: nitroglycerin.

glyptic
 * Of minerals, a natural resemblance to the carving or engraving on precious stones.

glyptogenesis
 * The sculpture of the Earth's surface by erosion.

glyptography
 * a. The art of engraving upon gems.

b. The descriptive science of engraved gems.

G.M.B.
 * Eng. Good merchantable brand, as applied to metal on the Metal Exchange.

gmelinite
 * A hexagonal mineral, (Na (sub 2) ,Ca)Al (sub 2) Si (sub 4) O (sub 12) .6H (sub 2) O ; zeolite group; forms transparent to translucent, pyramidal or tabular crystals, with other zeolites, in the amygdules of basaltic lava.

G-M tube
 * See: Geiger-Mueller tube.

gneiss
 * A foliated rock formed by regional metamorphism, in which bands or lenticles of granular minerals alternate with bands or lenticles in which minerals having flaky or elongate prismatic habits predominate. Generally less than 50% of the minerals show preferred parallel orientation. Although a gneiss is commonly feldspar- and quartz-rich, the mineral composition is not an essential factor in its definition. Varieties are distinguished by texture (e.g., augen gneiss), characteristic minerals (e.g., hornblende gneiss), or general composition and/or origins (e.g., granite gneiss).

gneissic structure
 * In a metamorphic rock, commonly gneiss, the coarse, textural lineation or banding of the constituent minerals into alternating silicic and mafic layers. Syn: gneissosity.

gneissosity
 * See: gneissic structure.