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

a-ag

a

a

a. Symbol in structural petrology for the direction of tectonic transport, similar to the direction in which cards might slide over one another. Striations in a slickensided surface are parallel to direction a.

b. A crystallographic axis: In the isometric system each axis is designated a; in hexagonal, tetragonal, and trigonal systems the nonunique axes are a; in the orthorhombic system a is always shorter than b with c either the longest or the shortest axis; in the monoclinic and triclinic systems a may be determined by one of several conventions.

a axis

a. One of the three crystallographic axes used as reference in crystal description. It is oriented horizontally, front to back.

b. One of the three reference axes used in describing a rock fabric possessing monoclinic symmetry, such as progressive simple shear. The a axis is the direction of tectonic transport, i.e., the direction of shear. Syn: a direction. The letter "a" usually appears in italics. CF: b axis; c axis.

abandoned mine See: abandoned workings.

abandoned workings

Excavations, either caved or sealed, that are deserted and in which further mining is not intended and open workings that are not ventilated and inspected regularly. Syn: abandoned mine.

Abbe jar

In mineral processing, a porcelain jar used for laboratory batch grinding tests in ceramic ware.

Abbe refractometer An instrument to determine the index of refraction of a liquid between two high-index glass prisms. CF: refractometer.

Abbe theory The visibility of an object under the microscope is directly proportional to the wavelength of light, and inversely to the aperture of lens.

Abbe tube mill A gear-driven tube mill supported on a pair of riding rings and distinguished by an Archimedes spiral, through which the ore is fed and discharged. Grinding is effected by flint pebbles fed into the mill. See also: ball mill.

ABC system A method of seismic surveying by which the effect of irregular weathering thickness may be determined by a simple calculation from reciprocal placement of shotholes and seismometers. The method was originally used to solve refraction problems arising from irregularities in the top of the high-velocity layer.

Abel's reagent Etching agent consisting of 10% chromium trioxide in water. Used in the analysis of carbon steels.

aberration a. The failure of a lens or mirror to bring the light rays to the same focus. When aberration is due to the form of the lens or mirror, it is called spherical aberration. When due to the different refrangibility of light of different colors, it is called chromatic aberration. When present in magnifiers it often causes inaccurate decisions as to flawlessness or color of gems. b. Distortion produced by a lens. It is spherical if a flat image appears closer to the viewer in the middle than toward the edges of the field of view. It is chromatic if the visible spectrum is spread to give both a red and a blue image. CF: achromatic; aplanatic lens; aplanachromatic lens. See also: chromatic aberration.

abime A large, steep-sided vertical shaft opening at the surface of the ground.

ablation breccia See: solution breccia.

A.B. Meco-Moore A bulky machine that cuts a deep web of coal up to 6 ft (1.8 m) and is used in cyclic mining in medium to thick seams. It runs on the floor of the seam and does not require a prop-free front. It carries two horizontal jibs, one cutting at floor level and the other at a height depending on seam conditions.

Abney level A surveying instrument for taking levels up steep slopes; also used as a clinometer.

abnormal place A working place in a coal mine with adverse geological or other conditions and in which the miner is unable to earn a wage, based on the pricelist, equal to or above the minimum wage. A term generally associated with stalls or pillar methods of working.

abraser A device for assessing the wear resistance of surfaces. The specimen to be tested is rubbed alternately by the flat faces of two weighted abrasive wheels that revolve in opposite directions through frictional contact with the specimen and exert a combined abrasive, compressive, and twisting action twice in each revolution of the specimen holder.

abrasion a. The mechanical wearing away of rock surfaces by friction and impact of rock particles transported by wind, ice, waves, running water, or gravity. Syn: corrasion. CF: attrition. b. The wearing away of diamonds, drill-bit matrices, and drill-stem equipment by frictional contact with the rock material penetrated or by contact with the cuttings produced by the action of the drill bit in drilling a borehole.

abrasion hardness Hardness expressed in quantitative terms or numbers indicating the degree to which a substance resists being worn away by frictional contact with an abrasive material, such as silica or carborundum grits. Also called abrasion resistance; wear resistance.

abrasion index The percentage of a specially prepared 3-in by 2-in (76-mm by 51-mm) sample of coke remaining on a 1/8-in (3.2-mm) mesh British Standards test sieve after the sample of coke has been subjected to a standardized abrasion procedure in a rotating drum.

abrasive a. Any natural or artificial substance suitable for grinding, polishing, cutting, or scouring. Natural abrasives include diamond, emery, garnet, silica sand, diatomite, and pumice; manufactured abrasives include esp., silicon carbide, fused alumina, and boron nitride. b. Tending to abrade or wear away.

abrasive blasting respirator A respirator designed to protect the wearer from inhalation or impact of, and abrasion by, materials used or generated in abrasive blasting.

abrasive formation A rock consisting of small, hard, sharp-cornered, angular fragments, or a rock, the cuttings from which, produced by the action of a drill bit, are hard, sharp-cornered, angular grains, which grind away or abrade the metal on bits and drill-stem equipment at a rapid rate. Syn: abrasive ground.

abrasive ground See: abrasive formation.

abrasive hardness test Test employing a rotating abrasive wheel or plate against which specimens are held. The specimens are abraded for a given number of revolutions, and the weight of material lost is a measure of the abrasive hardness.

abraum salts See: abraumsalze.

abraumsalze Ger. Mixed sulfates and chlorides of potassium, sodium, and magnesium overlying the rock salt in the Stassfurt salt deposits. Syn: abraum salts; stripping salt.

abriachanite An earthy, amorphous variety of crocidolite asbestos.

absolute a. In chemistry, free from impurity or admixture. b. In physics, not dependent on any arbitrary standard. c. Frequently used in the trades to indicate a thing as being perfect or exact. Abbrev. abs.

absolute age The geologic age of a fossil organism, rock, or geologic feature or event given in units of time, usually years. Commonly used as a syn. of isotopic age or radiometric age, but may also refer to ages obtained from tree rings, varves, etc. Term is now in disfavor as it implies a certainty or exactness that may not be possible by present dating methods; i.e., two absolute ages for the same pluton may disagree by hundreds of millions of years. CF: relative age. Syn: actual age.

absolute atmosphere An absolute unit of pressure equal to 1 million times the pressure produced on 1 cm (super 2) by the force of 1 dyn.

absolute bulk strength A measure of available energy per unit volume of explosive. Syn: bulk strength. See also: relative bulk strength.

absolute chronology Geochronology in which the time-order is based on absolute age, usually measured in years by radiometric dating, rather than on superposition and/or fossil content as in relative chronology.

absolute daily range During the 24 h of the day the difference between the maximum easterly and maximum westerly values of the magnetic declination at any point.

absolute humidity The content of water vapor in air, expressed as the mass of water per unit volume of air. CF: relative humidity. See also: humidity.

absolute isohypse A line that has the properties of both constant pressure and constant height above mean sea level. Therefore, it can be any contour line on a constant-pressure chart, or any isobar on a constant-height chart.

absolute ownership In law, an unqualified title to property and the unquestioned right to immediate and unconditional possession thereof. Applies to mining claims and properties.

absolute permeability A measure of possible flow of a standard liquid under fixed conditions through a porous medium when there is no reaction between the liquid and the solids. This measure is arbitrarily taken for isothermal viscous flow. It can be duplicated with gases if tests are so conducted that extrapolation to infinite pressure can be made; specific permeability.

absolute potential True potential difference between a metal and the solution in which it is immersed.

absolute pressure a. Total pressure at a point in a fluid equaling the sum of the gage pressure and the atmospheric pressure. b. Pressure measured with respect to zero pressure, in units of force per unit of area.

absolute roof The entire mass of strata overlying a coal seam or a subsurface point of reference. See also: nether roof.

absolute scale See: Kelvin temperature scale.

absolute temperature Temperature reckoned from absolute zero. See also: temperature.

absolute time Geologic time measured in terms of years by radioactive decay of elements. CF: relative time. See also: geochronology.

absolute viscosity See: viscosity coefficient.

absolute weight strength A measure of available energy per gram of explosive. Syn: weight strength. See also: relative weight strength.

absolute zero The temperature at which a gas would show no pressure if the general law for gases would hold for all temperatures. It is equal to -273.16 degrees C or -459 degrees F. CF: temperature.

absorbed water Water held mechanically in a soil mass and having physical properties not substantially different from those of ordinary water at the same temperature and pressure.

absorbent formation A rock or rock material, which, by virtue of its dryness, porosity, or permeability, has the ability to drink in or suck up a drilling liquid, as a sponge absorbs water. Syn: absorbent ground.

absorbent ground See: absorbent formation.

absorbents Substances, such as wood meal and wheat flour, that are forms of low explosive when mixed with metallic nitrates and tend to reduce the blasting power of the explosives, making them suitable for coal blasting.

absorber a. An apparatus in which gases are brought into intimate contact with an extended surface of an absorbing fluid so that they enter rapidly into solution. b. The resistance and capacitance in series that is placed across a break in an electrical circuit in order to damp any possible oscillatory circuit and would tend to maintain an arc or spark when a current is interrupted. Syn: spark absorber. c. Any material that absorbs or stops ionizing radiation, such as neutrons, gamma rays, alpha particles, and beta particles.

absorptiometer A device for measuring the solubility of a gas in a liquid.

absorption a. The phenomenon observed when a pleochroic mineral is rotated in plane polarized light. In certain positions, the mineral is darker than in others, owing to the absorption of light. b. In hydrology, a term applied to the entrance of surface water into the lithosphere by all methods. c. The reduction of light intensity in transmission through an absorbing substance or in reflection from a surface. In crystals, the absorption may vary with the wavelength and with the electric vector of the transmitted light with respect to crystallographic directions. d. Any mechanism by which energy, e.g., electromagnetic or seismic, is converted into heat. e. Taking up, assimilation, or incorporation, e.g., of liquids in solids or of gases in liquids. CF: adsorption. Syn: occlusion. f. The entrance of surface water into the lithosphere by any method.

absorption hygrometer A type of hygrometer with which the water vapor content of the atmosphere is measured by means of the absorption of vapor by a hygroscopic chemical. The amount of vapor absorbed may be determined in an absolute manner by weighing the hygroscopic material, or in a nonabsolute manner by measuring a physical property of the substance that varies with the amount of water vapor absorbed. The lithium chloride humidity strip and carbon-film hygrometer element are examples of the latter.

absorption loss a. The loss of water occurring during initial filling of a reservoir in wetting rocks and soil. b. That part of the transmission loss due to dissipation or the conversion of sound energy into some other form of energy, usually heat. This conversion may take place within the medium itself or upon a reflection at one of its boundaries.

absorption rate a. The rate, expressed in quantitative terms, at which a liquid, such as a drilling circulation medium, is absorbed by the rocks or rock materials penetrated by the drill bit. b. The amount of water absorbed when a brick is partially immersed for 1 min; usually expressed either in grams or ounces per minute. Also called suction rate; initial rate of absorption.

absorption spectra Specific wavelengths of electromagnetic radiation have precisely the energy to cause atomic or molecular transitions in substances they are passing through; their removal from the incident radiation produces reductions in intensity of those wavelengths, or absorption spectra, characteristic of the substance under study. CF: emission spectra.

absorption spectrum The array of absorption bands or lines seen when a continuous spectrum is transmitted through a selectively absorbing medium.

absorption tower A tower in which a liquid absorbs a gas.

abundant vitrain A field term denoting, in accordance with an arbitrary scale established for use in describing banded coal, a frequency of occurrence of vitrain bands comprising 30% to 60% of the total coal layer. CF: dominant vitrain; moderate vitrain; sparse vitrain.

abutment A surface or mass provided to withstand thrust, for example, the end supports of an arch or bridge. In coal mining, (1) the weight of the rocks above a narrow roadway is transferred to the solid coal along the sides, which act as abutments of the arch of strata spanning the roadway; and (2) the weight of the rocks over a longwall face is transferred to the front abutment (the solid coal ahead of the face) and the back abutment (the settled packs behind the face). See also: overarching weight; pressure arch; load transfer. Syn: arch structure.

abutment load In underground mining, the weight of rock above an excavation that has been transferred to the adjoining walls.

abutment pillars Pillars intended to support vertical load in excess of the weight of the strata directly above them. Generally, these abutment pillars are large pillars adjacent to smaller pillars, sometimes called yield pillars, which are incapable of carrying the weight of the strata above them.

abysmal See: abyssal.

abysmal sea That part of the sea occupying the ocean basins proper.

abyss a. A very deep, unfathomable place. The term is used to refer to a particularly deep part of the ocean, or to any part below 3,000 fathoms (18,000 ft or 5.5 km). b. Syn: pit; pot; pothole; chasm; shaft.

abyssal a. Pertaining to an igneous intrusion that occurs at considerable depth, or to the resulting rock; plutonic. CF: hypabyssal. b. Pertaining to the ocean environment or depth zone of 500 fathoms (3,000 ft or 915 m) or deeper; also, pertaining to the organisms of that environment. c. Of, or pertaining to, deep within the Earth, the oceanic deeps below 1,000 fathoms (6,000 ft or 1.83 km), or great depths of seas or lakes where light is absent. See also: plutonic. d. In oceanography, relating to the greatest depths of the ocean; relating to the abyssal realm. Syn: abysmal.

abyssal deposit A deposit of the deep sea, accumulating in depths of more than 1,500 fathoms (9,000 ft or 2.7 km) of water; these deposits comprise the organic oozes, various muds, and red clay of the deepest regions.

abyssal injection The process by which magmas, originating at considerable depths, are considered to have been driven up through deep-seated contraction fissures.

abyssal plain An area of the ocean floor with a slope of less than 1 in 1,000 or flat, nearly level areas that occupy the deepest portions of many ocean basins.

abyssal realm The deep waters of the ocean below 1,000 fathoms or 6,000 ft (1.83 km).

abyssal theory A theory of mineral-deposit formation involving the separation and sinking of ore minerals below a silicate shell during the cooling of the Earth from a liquid stage, followed by their transport to and deposition in the crust as it was fractured (Shand, 1947). Modern thought ascribes more complex origins to mineral deposits.

abyssal zone The marine-life zone of the deep sea embracing the water and bottom below a depth of 6,000 ft (1.83 km).

abyssobenthic Relating to that part of the abyssal realm that includes the ocean floor; pertaining to or living on the ocean floor at great depths.

abyssolith See: batholith.

abyssopelagic a. Relating to that part of the abyssal realm that excludes the ocean floor; floating in the depths of the ocean. b. Pertaining to that portion of the deep waters of the ocean that lie below depths of 6,000 ft (1.83 km).

ac

acanthite A monoclinic mineral, 4[Ag (sub 2) S] ; dimorphous with argentite, pseudohexagonal, in slender prisms; sp gr, 7.2 to 7.3; a source of silver.

accelerated weathering test A test to indicate the effect of weather on coal, in which the coal is alternately exposed to freezing, wetting, warming, and light; the alternation may be varied to suit. This test may be applied to other bituminous materials.

accelerator a. A machine that accelerates electrically charged atomic particles, such as electrons, protons, deuterons, and alpha particles, to high velocities. b. A substance added to increase the rate of a chemical reaction.

accelerometer A seismometer with response linearly proportional to the acceleration of earth materials with which it is in contact.

accented contour See: index contour.

acceptor A charge of explosives or blasting agent receiving an impulse from an exploding donor charge. Syn: receptor.

accessory a. Applied to minerals occurring in small quantities in a rock. The presence or absence of these minor minerals does not affect the classification or the naming of the rock. b. Fragments derived from previously solidified volcanic rocks of related origin; i.e., the debris of earlier lavas and pyroclastic rocks from the same cone. See also: accessory mineral. c. Said of pyroclastics that are formed from fragments of the volcanic cone or earlier lavas; it is part of a classification of volcanic ejecta based on mode of origin, and is equivalent to resurgent ejecta. CF: auxiliary.

accessory element See: trace element.

accessory mineral Any mineral the presence of which is not essential to the classification of the rock. Accessory minerals generally occur in minor amounts; in sedimentary rocks they are mostly heavy minerals. CF: essential mineral. Syn: accessory.

accessory plate a. The quartz wedge inserted in the microscope substage above the polarizer in order to estimate birefringence and to determine optical sign of uniaxial minerals. CF: quartz wedge. b. The selenite plate that gives the sensitive tint of a specimen between crossed nicols. c. The mica plate that retards yellow light. d. In polarized-light microscopy, an optical device that may be inserted into the light train to alter light interference after passage through, or reflection by, a crystalline material; e.g., quartz wedge, mica plate, gypsum plate, or Bertrand lens. e. In polarized-light microscopy, an optical compensator that may be inserted into the light train to alter birefringence after light passage through or reflection by an anisotropic material; e.g., quartz wedge, mica plate, gypsum plate, or Berek compensator. Syn: gips plate; glimmer plate; compensator. CF: Berek compensator; gypsum plate.

access road A route constructed to enable plant, supplies, and vehicles to reach a mine, quarry, or opencast pit. In remote and isolated regions, the provision of an access road may be very costly.

accidental inclusion See: xenolith; xenocryst.

accordion roller conveyor A roller conveyor with a flexible latticed frame that permits variation in length.

accretion vein A vein formed by the repeated filling of a channelway and its reopening by the development of fractures in the zone undergoing mineralization.

accumulation a. In coal mining, bodies of combustible gases that tend to collect in higher parts of mine workings and at the edge of goaves and wastes. They are found in cavities, at ripping lips, at other sheltered places protected from the ventilating current, and at the higher sides of rise faces. b. The concentration or gathering of oil or gas in some form of trap. Commercial accumulation is a volume or quantity sufficient for profitable exploitation.

accumulative rock See: cumulate.

accumulator a. A cylinder containing water or oil under pressure of a weighted piston for hydraulic presses, hoists, winches, etc. It is between the pumps and the presses, keeps a constant pressure on the system, and absorbs shocks. b. A storage battery. c. In oceanography, a spring of rubber or steel attached to a trawling warp, to lessen any sudden strain due to the trawl catching.

accumulator conveyor Any conveyor designed to permit accumulation of packages or objects. Usually roller, live roller conveyor, roller slat conveyor, or belt conveyor.

accuracy The degree of conformity with a standard, or the degree of perfection attained in a measurement. Accuracy relates to the quality of a result, and is distinguished from precision, which relates to the quality of the operation by which the result is obtained.

acetamide A trigonal mineral, CH (sub 3) CONH (sub 2) . Syn: acetic acid amine; ethanamide.

acetic acid amine See: acetamide.

acetylene The most brilliant of illuminating gases, C (sub 2) H (sub 2) . It may be produced synthetically from its elements, by incomplete combustion of coal gas, and commercially from calcium carbide, CaC (sub 2) . It also may be produced by reaction with water. Used in manufacturing explosives. Formerly used as an illuminating gas in mines and around drill rigs. When combined with oxygen, acetylene burns to produce an intensely hot flame and hence now is used principally in welding and metal-cutting flame torches. Syn: ethyne; ethine. CF: gas.

acetylene lamp See: carbide lamp.

acetylene tetrabromide Yellowish liquid; CHBr (sub 2) CHBr (sub 2) ; sp gr, 2.98 to 3.00; boiling point, 239 to 242 degrees C with decomposition (at 760 mm); also, boiling point, 151 degrees C (at 54 mm); melting point, 0.1 degrees C; and refractive index, 1.638. Used for separating minerals by specific gravity; a solvent for fats, oils, and waxes; a fluid in liquid gases; and a solvent in microscopy.

achavalite Former name for iron selenide, FeSe .

Acheson graphite Artificial graphite made from coke by electric furnace heating.

Acheson process A process for the production of artificial or synthetic graphite. It consists of sintering pulverized coke in the Acheson furnace at 2,760 to 3,316 degrees C.

achirite Former name for dioptase.

achroite A colorless variety of elbaite tourmaline used as a gemstone.

achromatic In microscopy, a compound lens that does not spread white light into its spectral colors. CF: aberration. See also: aplanachromatic lens.

acicular a. A mineral consisting of fine needlelike crystals; e.g., natrolite. b. Slender needlelike crystal. c. Refers to needlelike crystals. CF: equant; sagenitic; tabular; rodlike.

acicular bismuth See: aikinite.

acicular powder In powder metallurgy, needle-shaped particles.

aciculite See: aikinite.

acid a. A solution of pH less than 7.0 at 25 degrees C. b. A substance containing hydrogen that may be replaced by metals with the formation of salts.

acid Bessemer converter One lined with acid refractories.

acid bottom and lining The inner bottom and lining of a melting furnace, consisting of materials like sand, siliceous rock, or silica brick, which give an acid reaction at the operating temperature. Syn: acid lining.

acid clay a. A clay that is used mainly as a decolorant or refining agent, and sometimes as a desulfurizer, coagulant, or catalyst. b. A clay that yields hydrogen ions in a water suspension; a hydrogen clay.

acid cure In uranium extraction, sulfation of moist ore before leaching.

acid-dip survey A method of determining the angular inclination of a borehole in which a glass, test-tubelike bottle partly filled with a dilute solution of hydrofluoric acid is inserted in a watertight metal case. When the assemblage is lowered into a borehole and left for 20 to 30 min, the acid etches the bottle at a level plane from which the inclination of the borehole can be measured. CF: Kiruna method. Syn: acid-dip test; acid test; acid-etch tube.

acid-dip test See: acid-dip survey.

acid drainage Water with a pH of less than 6.0 and in which total acidity exceeds total alkalinity; discharged from an active, inactive, or abandoned surface coal mine and reclamation operation.

acid electric furnace An arc furnace having an acid refractory hearth.

acid embrittlement A form of hydrogen embrittlement that may be induced in some metals by acid treatment.

acid-etch tube A soda-lime glass tube charged with dilute hydrofluoric acid, left in a borehole for 20 to 30 min to measure inclination as indicated by the angle of etch line on the tube. May be fitted in a clinometer. Syn: acid-etch vial; culture tube; etch tube; sargent tube. See also: acid-dip survey.

acid-etch vial See: acid-etch tube.

acid flux Metallurgically acid material (usually some form of silica) used as a flux.

acid-forming materials Earth materials that contain sulfide minerals or other materials that, if exposed to air, water, or weathering processes, form acids that may create acid drainage.

acidic a. A descriptive term applied to those igneous rocks that contain more than 60% silica. Acidic is one of four subdivisions of a widely used system for classifying igneous rocks based on their silica content: acidic, intermediate, basic, and ultrabasic. b. Applied loosely to any igneous rock composed predominantly of light-colored minerals having a relatively low specific gravity. CF: felsic. Syn: silicic.

acidization The process of forcing acid into a limestone, dolomite, or sandstone in order to increase permeability and porosity by dissolving and removing a part of the rock constituents. It is also used to remove mud injected during drilling. The general objective of acidization is to increase productivity. Syn: acidizing.

acidize To treat a limestone or dolomitic formation with dilute hydrochloric acid to enlarge its void spaces.

acidizing See: acidization.

acid leach Metallurgical process for dissolution of metals by means of acid solution. Examples include extraction of copper from oxide- or sulfide-bearing ore and dissolution of uranium from sandstone ores. Acid leaching can occur on heap-leach pads or in situ.

acid lining See: acid bottom and lining.

acid mine drainage a. Acidic drainage from bituminous coal mines containing a high concentration of acidic sulfates, esp. ferrous sulfate. See also: acid water. b. Drainage with a pH of 2.0 to 4.5 from mines and mine wastes. It results from the oxidation of sulfides exposed during mining, which produces sulfuric acid and sulfate salts. The acid dissolves minerals in the rocks, further degrading the quality of the drainage water.

acid mine water a. Mine water that contains free sulfuric acid, mainly due to the weathering of iron pyrites. A pit water, which corrodes iron pipes and pumps, usually contains a high proportion of solids per gallon, principally the sulfates of iron, chiefly ferrous and alumina. See also: acid water. b. Where sulfide minerals break down under chemical influence of oxygen and water, the mine drainage becomes acidic and can corrode ironwork. If it reaches a river system, biological damage may also result.

acid neutralizers Calcium carbonate, CaCO (sub 3) , magnesium carbonate, MgCO (sub 3) , and china clay, which neutralize free acids, thereby preventing explosives from decomposing in storage. They also have a cooling effect and tend to reduce the sensitivity of the explosive.

acid open-hearth steel Low-phosphorus pig iron treated in an acid (silica or sand)-lined furnace.

acid ore See: siliceous ore.

acid process A steelmaking process--Bessemer, open-hearth, or electric--in which the furnace is lined with a siliceous refractory, and for which pig iron low in phosphorus is required, as this element is not removed. See also: acid steel; basic process.

acid-recovery operator In the coke products industry, a person who recovers sulfuric acid used in processing coke-gas byproducts by cooking sludge with steam in acid regenerator pots. Syn: acid regenerator.

acid refractory material A general term for those types of refractory material that contain a high proportion of silica; e.g., silica refractories (greater than 92% SiO (sub 2) ) and siliceous refractories (78% to 92% SiO (sub 2) ). The name derives from the fact that silica behaves chemically as an acid and at high temperatures reacts with bases such as lime or alkalies.

acid refractory product Refractory product made of clay-silica mixture or pure silica.

acid regenerator See: acid-recovery operator.

acid rock drainage Drainage that occurs as a result of natural oxidation of sulfide minerals contained in rock that is exposed to air and water. It is not confined to mining activities, but can occur wherever sulfide-bearing rock is exposed to air and water. Abbrev. ARD.

acid slag Slag that contains substantial amounts of active silica.

acid sludge Products of refining of tar, shale oil, and petroleum in which sulfuric acid reacts to form a sulfonic acid mixture, green acids, and mahogany acids and salts. Used in the flotation process and in proprietary collector agents for flotation of iron ores.

acid soil A soil with a pH of less than 7.0.

acid steel Steel melted in a furnace with an acid bottom and lining and under a slag containing an excess of an acid substance, such as silica. See also: acid process.

acid strength Related to ability to liberate hydrogen ions to solution, and hence to electrical conductivity of equivalent aqueous solutions of acids.

acid test a. See: acid-dip survey. b. A severe or decisive trial, as of usability or authenticity.

acid water Water charged naturally with carbon dioxide. Also applied to natural waters containing sulfur compounds, esp. sulfates. See also: acid mine water; acid mine drainage.

aciform Needle-shaped.

aciniform A mineral aggregate shaped like a cluster of grapes. Also, full of small kernels like a grape. Syn: acinose; acinous.

acinose a. Grapelike; applied to the structure of clustered mineral aggregates. Syn: aciniform; acinous. b. Granulated; like grape seeds; applied to the texture of some mineral aggregates.

acinote Former name for actinolite.

acinous See: aciniform; acinose.

aclinal A little-used term said of strata that have no inclination; horizontal. Syn: aclinic.

aclinic See: aclinal.

aclinic line The line through those points on the Earth's surface at which the magnetic inclination is zero. The aclinic line is a particular case of an isoclinic line.

acmite A brown variety of aegirine having pointed terminations. See also: aegirine; pyroxene.

acopolado Mex. Ore containing 50 to 60 oz/st (1.56 to 1.88 kg/t) of silver.

acoustic Used when the term that it modifies designates something that has the properties, dimensions, or physical characteristics associated with sound waves.

acoustical well logging Any determination of the physical properties or dimensions of a borehole by acoustical means, including measurement of the depth of fluid level in a well.

acoustic attenuation log In theory, a log designed to measure the manner in which the energy of elastic waves is dissipated in passing through rock. Although no practical log of this type has yet evolved, the belief that a log of this parameter would permit the estimation of the permeability of formations would seem to ensure such a development since no log has been developed to record permeability.

acoustic dispersion The change of speed of sound with frequency.

acoustic impedance The acoustic impedance of a given surface area of an acoustic medium perpendicular, at every point, to the direction of propagation of sinusoidal acoustic waves of given frequency, and having equal acoustic pressures and equal volume velocities per unit area at every point of the surface at any instance, is the quotient obtained by dividing (1) the phasor corresponding to the acoustic pressure by (2) the phasor corresponding to the volume velocity. See also: impedance. acoustic interferometer An instrument for making physical observations upon standing waves. It may be used, e.g., to measure velocity, wavelength, absorption, or impedance. acoustic log A continuous record made in a borehole showing the velocity of sound waves over short distances in adjacent rock; velocity is related to porosity and nature of the liquid occupying pores. acoustic-radiation pressure A unidirectional steady-state pressure exerted upon a surface exposed to an acoustic wave. Such a steady pressure is usually quite small in magnitude and is really observable only in the presence of very intense sound waves.

acoustic radiometer An instrument for measuring acoustic-radiation pressure by determining the unidirectional steady-state force resulting from reflection or absorption of a sound wave at its boundaries.

acoustic resistance Product of longitudinal wave velocity and density, being the property that controls the reflective power at a boundary plane.

acoustics The study of sound, including its production, transmission, reception, and utilization, esp. in fluid media such as air or water. With reference to Earth sciences, it is esp. relevant to oceanography. The term is sometimes used to include compressional waves in solids; e.g., seismic waves.

acoustic scattering The irregular reflection, refraction, or diffraction of sound waves in many directions.

acoustic sounding The indirect evaluation of water depth, using the principle of measuring the length of time necessary for a sound wave to travel to the bottom, reflect, and travel back to the water surface.

acoustic-strain gage An instrument for measuring strains; e.g., in concrete linings to shafts or roadways. It contains a length of fine wire under tension, the tension being varied by the strain to which the gage is subjected. The measurement made is that of the frequency of vibration of the wire when it is plucked by means of an electromagnetic impulse, and this measurement can be made with great accuracy. The gage is highly stable, and readings can be made over a period of years without any fear of zero drift. See also: electrical resistance strain gage; mechanical extensometer.

acoustic theodolite An instrument designed to provide a continuous vertical profile of ocean currents at a specific location.

acoustic wave a. The waves that contain sound energy and by the motion of which sound energy is transmitted in air, in water, or in the ground. The wave may be described in terms of change of pressure, of particle displacement, or of density. b. Used increasingly to study the physical properties of rocks and composition of gases. Investigations may be made both in situ and in the laboratory.

acquired lands Defined by the U.S. Department of the Interior as "lands in Federal ownership which were obtained by the Government through purchase, condemnation, or gift, or by exchange for such purchased, condemned, or donated lands, or for timber on such lands. They are one category of public lands." Public land laws are generally inapplicable to acquired lands.

acre a. A measure of surficial area, usually of land. The statute acre of the United States and England contains 43,560 ft (super 2) (4,840 yd (super 2); 4,047 m (super 2) ; or 160 square rods). The so-called Scotch acre contains about 6,150 yd (super 2) (5,142 m (super 2) ), and the Irish acre 7,840 yd (super 2) (6,555 m (super 2) ). There are various special or local acres in England (as in Cheshire or among the hop growers), varying from 440 yd (super 2) (368 m (super 2) ) to more than 10,000 yd (super 2) (8,361 m (super 2) ). b. Can. In Quebec, a linear measure that equals the square root of 43,560, or approx. 208.7 ft (63.6 m). c. For the calculation of coal reserves, a convenient rule is to allow 1,200 st/ft (coal thickness) per acre (8,821 t/m/ha). For known and dependable areas, 1,500 st/ft per acre (11,027 t/m/ha) may be used.

acreage rent Royalty or rent paid by the lessee for working and disposing of minerals at the rate of so much per acre.

acre-foot The quantity of water that would cover 1 acre, 1 ft deep (1 ha, 13.6 cm deep). One acre-foot contains 43,560 ft (super 3) (1,233 m (super 3) ).

acre-inch The volume of water, soil, or other material that will cover 1 acre, 1 in deep (1 ha, 1.1 cm deep).

acre-yield The average quantity of oil, gas, or water recovered from 1 acre (0.4 ha) of a reservoir.

actetic acid amine See: acetamide.

actinide A chemical element with atomic number greater than 88; all are radioactive. Syn: actinide element.

actinide element a. One of the group of chemical elements of increasing atomic number, starting with actinium (atomic number 89) and extending through atomic number 103. These elements occupy one single place in the extended periodic table, in the same group into which the rare-earth elements (lanthanides) are classified. See also: actinide. b. One of the radioactive elements, atomic numbers 89 to 103.

actinolite A monoclinic mineral, 2[Ca (sub 2) (Mg,Fe) (sub 5) Si (sub 8) O (sub 22) (OH) (sub 2) ] in the hornblende series Mg/(Mg+Fe (super 2+) ) = 0.5 to 0.89 of the amphibole group; forms a series with tremolite; green, bladed, acicular, fibrous (byssolite asbestos), or massive (nephrite jade); prismatic cleavage; in low-grade metamorphic rocks. Syn: actinote; strahlite. CF: tremolite.

actinote See: actinolite.

activated alumina Highly porous, granular aluminum oxide that preferentially absorbs liquids from gases and vapors, and moisture from some liquids.

activated carbon Carbon, mostly of vegetable origin, and of high adsorptive capacity. Syn: activated charcoal.

activated charcoal See: activated carbon.

activated clay A clay whose adsorbent character or bleaching action has been enhanced by treatment with acid.

activated coal plow With a view to applying the coal plow to seams too hard to be sheared by the normal cutting blade, German mining engineers have developed various types of power-operated cutters. One consists of a series of compressed-air picks mounted above each other; another, of a resonance pattern, houses two high-speed motors eccentrically mounted and rotating in opposite directions. The latter imparts a vibration to the cutting edge equivalent to 2,500 blows per minute with a stroke of 3/16 to 1/4 in (4.8 to 6.4 mm) and a force of approx. 200 st (181 t).

activated plow See: Huwood slicer.

activating agent a. A substance that when added to a mineral pulp promotes flotation in the presence of a collecting agent. Syn: activator. b. Reagent used particularly in differential mineral flotation to help cleanse the mineral surface so that a collector may adhere to it and permit or aid its floatability. Frequently used to allow floating minerals that had been previously depressed.

activation a. In the flotation process of mineral dressing, the process of altering the surface of specific mineral particles in a mineral pulp to promote adherence of certain reagents. b. The changing of the passive surface of a metal to a chemically active state. CF: passivation. c. In the flotation process of ore beneficiation, the process of altering the surface of specific mineral particles in an ore pulp to promote adherence of certain reagents. d. The process of making a material radioactive by bombardment with neutrons, protons, or other nuclear particles. See also: activation analysis.

activation analysis A method for identifying and measuring the chemical elements in a sample to be analyzed. The sample is first made radioactive by bombardment with neutrons, charged particles, or other nuclear radiation. The newly radioactive atoms in the sample give off characteristic nuclear radiations that can identify the atoms and indicate their quantity. See also: activation.

activator a. In flotation, a chemical added to the pulp to increase the floatability of a mineral in a froth or to refloat a depressed (sunk) mineral. Also called activating reagent. b. A reagent that affects the surface of minerals in such a way that it is easy for the collector atoms to become attached. It has the opposite effect of a depressor. CF: depressor. c. A substance that is required in trace quantities to impart luminescence to certain crystals. d. Ions that are photon emitters. e. Any agent that causes activation. See also: activating agent.

active agent Surface-active substance that immunizes solids against a parting liquid.

active earth pressure The minimum value of lateral earth pressure exerted by soil on a structure, occurring when the soil is allowed to yield sufficiently to cause its internal shearing resistance along a potential failure surface to be completely mobilized. See also: surcharge. CF: passive earth pressure.

active entry An entry in which coal is being mined from a portion thereof or from connected sections.

active fault One liable to further movement. CF: passive fault.

active layer a. The surficial deposit that undergoes seasonal changes of volume, swelling when frozen or wet, and shrinking when thawing and drying. b. A surface layer of ground, above the permafrost, that is frozen in the winter and thawed in the summer. Its thickness ranges from several centimeters to a few meters.

active mining area a. The area, on and beneath land, used or disturbed in activity related to the extraction, removal, or recovery of coal from its natural deposits. This term excludes coal preparation plants, areas associated with coal preparation plants, and post-mining areas. b. The area in which active mining takes place relative also to extraction of metal ores, industrial minerals, and other minerals of economic value.

active workings All places in a mine that are ventilated and inspected regularly.

activity a. In nuclear physics, the rate of decay of atoms by radioactivity. It is measured in curies. b. The ideal or thermodynamic concentration of a substance, the substitution of which for the true concentration, permits the application of the law of mass action. See also: ionization constant.

actual age See: absolute age.

actual breaking strength The breaking load obtained from a tensile test to destruction on a sample of rope.

actual horsepower The horsepower really developed, as proved by trial.

actual performance curve A performance curve showing the results actually obtained from a coal preparation treatment.

actuated roller switch A switch placed in contact with the belt conveyor immediately preceding the conveyor it is desired to control. In the centrifugal sequence control switch, a driving pulley bears against the driving belt; as the latter moves, the pulley rotates and the governor weights attached to the pulley shaft are flung out and so complete an electrical pilot circuit and thus start the subsidiary belt.

acute bisectrix a. The line that bisects the acute angle of the optic axes of biaxial minerals. b. The angle <90 degrees between the optic axes in a biaxial crystal, bxa. CF: optic angle.

ad

adamantine a. Like the diamond in luster. b. Diamond hard. A commercial name for chilled steel shot used in the adamantine drill, which is a core-barrel type of rock-cutting drill with a cutting edge fed by these shots. CF: vitreous.

adamantine luster Diamondlike luster.

adamellite See: quartz monzonite.

adamic earth A term used for common clay, in reference to the material of which Adam, the first man, was made; specif. a kind of red clay.

adamite A rare hydrous zinc arsenate, Zn (sub 2) (AsO (sub 4) )(OH) , occurring granular or in crusts and crystallizing in the orthorhombic system. Weakly radioactive; variable color--yellowish, greenish, or violet, rarely colorless or white; found in the oxidized zone of zinc orebodies. Associated with smithsonite, calcite, malachite, hemimorphite, limonite, and azurite. Small amounts of uranium have been found in some specimens of adamite.

Adam's snuffbox A greenish-black muscovite found in a schist at Derby, VT; has been called margarodite. � [�� (�� �k� � � � DICTIONARY TERMS:Adam's snuffbox Hollow, roughly rectangular pebble Hollow, roughly rectangular pebble lined with goethite; Lenham beds, Netley Heath, Surrey, U.K.

ada mud A conditioning material that may be added to drilling mud in order to obtain satisfactory cores and samples of formations.

adapter trough A short section of a shaker conveyor trough that serves as a connecting link between any two sizes of trough.

added diamonds As used by the diamond-bit manufacturing industry, the number or carat weight of new diamonds that must be added to the resettable diamonds salvaged from a worn bit in order to have enough to set a new bit.

additive A correction applied to times of seismic reflections measured from an arbitrary time origin. The additive is normally applied for the purpose of translating the time origin to correspond to the datum elevation chosen for computation, and it is algebraic in sign.

addlings A term used in the northern and parts of other coalfields in Great Britain to describe earnings or wages.

Adeline steelmaking process A process of producing precision castings of steel or steel alloys, which comprises first forming the steel or steel alloy in molten form by the aluminothermic process, by igniting a mixture of iron ore and aluminum; then running the molten metal into a mold prepared by packing a refractory mold composition around a model made of wax or other comparatively low-melting-point substance and heating to melt out the wax and consolidate the mold; and finally centrifuging the mold.

adelite a. An orthorhombic mineral, CaMg(AsO (sub 4) )(OH) ; occurs with manganese ores. b. The mineral group adelite, austinite, conichalcite, duftite, and gabrielsonite.

ader wax See: ozocerite.

adhesion a. The molecular force holding together two different substances that are in contact, as water in the pore spaces of a rock. CF: cohesion. b. Shearing resistance between soil and another material under zero externally applied pressure. c. In the flotation process, the attachment of a particle to air-water interface or to a bubble.

adhesive slate A very absorbent slate that adheres to the tongue if touched by it.

adiabatic calorimeter A calorimeter that practically remains unaffected by its surroundings and neither gains nor loses heat.

adiabatic compression Compression in which no heat is added to or subtracted from the air and the internal energy of the air is increased by an amount equivalent to the external work done on the air. The increase in temperature of the air during adiabatic compression tends to increase the pressure on account of the decrease in volume alone; therefore, the pressure during adiabatic compression rises faster than the volume diminishes.

adiabatic efficiency A compression term obtained by dividing the power theoretically necessary to compress the gas and deliver it without loss of heat, by the power supplied to the fan or compressor driveshaft.

adiabatic expansion Expansion in which no heat is added to or subtracted from the air, which cools during the expansion because of the work done by the air.

adiabatic temperature The temperature that would be attained if no heat were gained from or lost to the surroundings.

adiabatic temperature change The compression of a fluid without gain or loss to the surroundings when work is performed on the system and produces a rise of temperature. In very deep water such a rise of temperature occurs and must be considered in the vertical temperature distribution.

adinole An argillaceous sediment that has undergone albitization as a result of contact metamorphism along the margins of a sodium-rich mafic intrusion. CF: spilosite; spotted slate.

adipite An aluminosilicate of calcium, magnesium, and potassium having the composition of chabazite.

adipocerite See: hatchettite.

adipocire See: hatchettite.

a direction See: a axis.

adit a. A horizontal or nearly horizontal passage driven from the surface for the working or dewatering of a mine. If driven through the hill or mountain to the surface on the opposite side, it would be a tunnel. Syn: drift; adit level. See also: tunnel. b. As used in the Colorado statutes, it may apply to a cut either open or undercover, or open in part and undercover in part, dependent on the nature of the ground. c. A passage driven into a mine from the side of a hill.

adit end The furthermost end or part of an adit from its beginning or the very place where the miners are working underground toward the mine.

adit level Mine workings on a level with an adit. See also: adit.

adjacent sea A sea adjacent to and connected with the oceans, but semienclosed by land. The North Polar, Mediterranean, and Caribbean Seas are examples. Syn: marginal sea.

adjustment of error Method of distributing the revealed irregularities over a series of results.

adjutage Nozzle or tube from which hydraulic water is discharged. Syn: ajutage.

admission See: admittance.

admittance a. In a crystal structure, substitution of a trace element for a major element of higher valence; e.g., Li (super +) for Mg (super 2+) . Admitted trace elements generally have a lower concentration relative to the major element in the mineral than in the fluid from which the mineral crystallized. CF: capture; camouflage. Syn: admission. b. The reciprocal of impedance or the ratio of complex current to voltage in a linear circuit.

adobe A fine-grained, usually calcareous, hard-baked clayey deposit mixed with silt, usually forming as sheets in the central or lower parts of desert basins, as in the playas of the southwestern United States and in the arid parts of Mexico and South America. It is probably a windblown deposit, although it is often reworked and redeposited by running water.

adobe charge A mud-covered or unconfined explosive charge fired in contact with a rock surface without the use of a borehole. Syn: bulldoze; mudcapping.

adobe flat A generally narrow plain formed by sheetflood deposition of fine sandy clay or adobe brought down by an ephemeral stream, and having a smooth, hard surface (when dry) usually unmarked by stream channels.

adobe shot Ordinarily referred to as a dobe shot. A stick or part of a stick of dynamite is laid on the rock to be broken and covered with mud to add to the force of the explosion. A mudcap shot.

adsorption a. Adherence of gas molecules, or of ions or molecules in solution, to the surface of solids with which they are in contact, as methane to coal or moisture to silica gel. CF: absorption. b. The assimilation of gas, vapor, or dissolved matter by the surface of a solid or liquid. c. The attachment of a thin film of liquid or gas, commonly monomolecular in thickness, to a solid substrate.

adsorption analysis Separation by differential adsorption.

adular See: adularia.

adularescence a. A milky white to bluish sheen in gemstones. b. The changeable white to pale bluish luster of an adularia cut cabochon. c. A floating, billowy, white or bluish light, seen in certain directions as a gemstone (usually adularia) is turned, caused by diffused reflection of light from parallel intergrowths of another feldspar of slightly different refractive index from the main mass. Syn: schiller.

adularia A colorless, moderate- to low-temperature variety of orthoclase feldspar typically with a relatively high barium content. Syn: adular.

adularia moonstone Precious moonstone, a gem variety of adularia.

advance a. The work of excavating as mining goes forward in an entry and in driving rooms; to extract all or part of an area; first mining as distinguished from retreat. b. Rate at which a drill bit penetrates a rock formation. c. Feet drilled in any specific unit of time. d. The linear distance (in feet or meters) driven during a certain time in tunneling, drifting, or in raising or sinking a shaft.

advance development S. Afr. Development to provide an ore reserve in advance of mining operations.

advanced gallery In tunnel excavation, a small heading driven in advance of the main tunnel.

advanced materials Materials developed since 1960 and being developed at present that exhibit greater strength, higher strength-density ratios, greater hardness, and/or one or more superior thermal, electrical, optical, or chemical properties, when compared with traditional materials (Sorrel, 1987) and with properties needed to perform a specific function and often entirely new functions.

advance gate Gate road that is driven simultaneously with the longwall coal face, when the advancing longwall technique is used, but which is maintained some 10 to 20 yd (9 to 18 m) or more in advance of the face. The area immediately ahead of the coal face is therefore preexplored, and steps can be taken to cope with minor disturbances and thus prevent a serious loss of output.

advance overburden Overburden in excess of the average overburden-to-ore ratio that must be removed in opencut mining.

advance per round The length, measured along the longitudinal axis of the working, tunnel, or gallery, of the hollow space broken out by each round of shots. For raises, it is upward advance; for sunk shafts, downward advance.

advance stope A stope in which sections of the face or some pillars are a little in advance of the others. This is achieved either by beginning the stoping of the section that is to be advanced earlier, or by proceeding more quickly.

advance stripping The removal of overburden required to expose and permit the minable grade of ore to be mined. The removal of overburden is known as stripping.

advance wave The air-pressure wave preceding the flame in a coal-dust explosion. The bringing of the dust into suspension is accomplished by such a wave and the violent eddies resulting therefrom. Syn: pioneer wave.

advance working Mine working that is being advanced into the solid, and from which no pillar is being removed. See also: first working.

advancing Mining from the shaft out toward the boundary. See also: working out.

advancing longwall A longwall mining technique, most commonly found in European coal mines, where the gate roads are advanced while the longwall face is advanced toward the mining limits. The gate roads are maintained throughout the worked-out portion of the longwall panel.

adventurine Spelling variant of aventurine.

adverse To oppose the granting of a patent to a mining claim.

adverse claim A claim made to prevent the patenting of part of the ground within the area in question; e.g., an adverse claim is made by a senior locator to exclude the part of his or her claim that is overlapped by the claim of a junior locator, when the junior locator is applying for patent.

adverse intent The terms "claim of right," "claim of title," and "claim of ownership," when used in the books to express adverse intent, mean nothing more than the intention of the dissessor to appropriate and use the land as his or her own to the exclusion of all others, irrespective of any semblance or shadow of actual title.

advertised out A term used to express the result of the action of a joint owner of a mining claim who by proper notices causes the interest of the co-owner to be forfeited for failure to perform his or her share of the assessment work.

ae

aedelforsite A name given to (1) a mixture of wollastonite, quartz, and feldspar from Edelfors, Sweden; (2) impure wollastonite from Giellebak, Sweden (called also gillebackit); and (3) impure laumontite, under the impression that they were new minerals. Syn: edelforsite.

aedelite See: prehnite.

AED process An electrostatic process under development, in which fine-size dry coal is passed through an ionized field that selectively charges the coal and the liberated mineral matter. The output of the ionizer is then fed into an electrostatic separator where the coal and impurities are separated. aegirine A sodium-ferric iron silicate, NaFe (super 3+) Si (sub 2) O (sub 6) , occurring commonly in soda-rich igneous rocks; monoclinic; Mohs hardness, 6 to 6.5; sp gr, 3.40 to 3.55. Syn: acmite; aegirite. See also: pyroxene. aegirine-augite A monoclinic mineral, (Ca,Na)(Ca,Mg,Fe)Si (sub 2) O (sub 6) , in the range 20% augite to 20% aegirine end members of the pyroxene group. Formerly called acmite-augite, aegirineaugite.

aegirite Former spelling of aegirine. See also: pyroxene; aegirine.

aenigmatite a. A triclinic mineral, Na (sub 2) Fe (sub 5) (super 2+) TiSi (sub 6) O (sub 20) ; a rare titanium-bearing silicate; black color; found associated with alkalic rocks. b. The mineral group aenigmatite, rhoenite, serendibite, and welshite. CF: enigmatite.

aeolian See: eolian.

Aeonite Trade name for a bitumen allied to wurtzilite. Similar to elaterite.

aerate a. To expose to the action of the air; to supply or to charge with air. b. To charge with carbon dioxide or other gas, as soda water.

aeration a. The introduction of air into the pulp in a flotation cell in order to form air bubbles. b. In mineral beneficiation, use of copious air bubbled into mineral pulps (1) to provide oxygen in cyanidation, (2) to prevent settlement of solids, and (3) to remove aerophilic minerals in froth flotation by binding them into a mineralized froth that is temporarily stabilized by frothing agents. c. The process of relieving the effects of cavitation by admitting air to the section affected.

aeration zone The zone in which the interstices of the functional permeable rocks are not (except temporarily) filled with water under hydrostatic pressure; the interstices are either not filled with water or are filled with water that is held by capillarity.

aerator An apparatus for charging water with gas under pressure, esp. with carbon dioxide.

aerial Relating to the air or atmosphere. Subaerial is applied to phenomena occurring under the atmosphere as subaqueous is applied to phenomena occurring underwater.

aerial cableway An arrangement of overhead cable supporting a traveling carriage from which is suspended a skip or container that can be lowered and raised at any desired point.

aerial mapping The taking of aerial photographs for making maps and for geologic interpretation.

aerial photograph Any photograph taken from the air, such as a photograph of a part of the Earth's surface taken by a camera mounted in an aircraft. Syn: air photograph.

aerial photomosaic See: mosaic.

aerial railroad A system of cables from which to suspend cars or baskets, as in hoisting ore. See also: aerial tramway.

aerial ropeway System of ore transport used in rough or mountainous country. A cable is carried on pylons, and loaded buckets are (1) towed from loading point to discharge, (2) suspended from a carriage running on this cable and then returned empty along a second cable, or (3) the whole cable moves continuously carrying buckets that hang from saddle clips and are loaded and discharged automatically or by hand control. Syn: overhead ropeway. See also: bicable; monocable; aerial tramway; telpher.

aerial spud A cable for moving and anchoring a dredge.

aerial survey a. A survey using aerial photographs as part of the surveying operation. b. The taking of aerial photographs for surveying purposes.

aerial tramway A system for the transportation of material, such as ore or rock, in buckets suspended from pulleys or grooved wheels that run on a cable, usually stationary. See also: tramway; aerial railroad; aerial ropeway.

aerobe An organism that lives in the presence of free oxygen. The oxygen is usually used in the cell's metabolism. See also: aerobic.

aerobic a. Said of an organism (esp. a bacterium) that can live only in the presence of free oxygen; also, said of its activities. Syn: aerobe. b. Said of conditions that can exist only in the presence of free oxygen. CF: anaerobic.

aeroclay Clay, particularly china clay, that has been dried and air separated to remove any coarse particles.

aerodynamical efficiency This furnishes a measure of the capacity of a fan to produce useful depression (or positive pressure in the case of a forcing fan) and indicates the extent to which the total pressure produced by the fan is absorbed within the fan itself.

aerodynamic diameter The diameter of a unit density sphere having the same terminal settling velocity as the particle in question.

aerodynamic fan A fan that consists of several streamlined blades mounted in a revolving casing. The cross section and spacing of the blades are designed aerodynamically. This design ensures that the air flows without recirculation between the blades and leaves the rotor in a steady and regularly distributed stream. This appreciably reduces frictional, conversion, and recirculation losses. Fans of a convenient size can handle large volumes of air at the highest pressures likely to be required in mine ventilation.

aerodynamic instability Flutter that may occur in a structure exposed to wind force. This form of instability can be guarded against by suitable design.

aeroembolism a. The formation or liberation of gases in the blood vessels of the body, as brought on by a change from a high, or relatively high, atmospheric pressure to a lower one. b. The disease or condition caused by the formation or liberation of gases in the body. The disease is characterized principally by neuralgic pains, cramps, and swelling, and sometimes results in death. Syn: decompression sickness.

aerofall mill A short, cylindrical grinding mill with a large diameter, used dry, with coarse lumps of ore, pebbles, or steel balls as crushing bodies. The mill load is flushed with an air stream to remove finish mesh material.

aerofloc Synthetic water-soluble polymer used as a flocculating agent.

aerofoil-vane fan An improved centrifugal-type mine fan. The vanes, of aerofoil section, are curved backward from the direction of rotation. This fan is popular in British coal mines, and total efficiencies of about 90% have been obtained. See also: mine-ventilation fan.

aerohydrous a. Enclosing a liquid in the pores or cavities, as some minerals. b. Characterized by the presence of both air and water.

aeroides Pale sky-blue aquamarine beryl.

aeromagnetic prospecting A technique of geophysical exploration of an area using an airborne magnetometer to survey that area. Syn: airborne magnetic prospecting.

aerometer An instrument for ascertaining the weight or the density of air or other gases.

aerosite Former name for pyrargyrite.

aerosol a. A suspension of ultramicroscopic solid or liquid particles in air or gas, as smoke, fog, or mist. b. Particles, solid or liquid, suspended in air. c. A sol in which the dispersion medium is a gas (usually air) and the dispersed or colloidal phase consists of solid particles or liquid droplets, e.g., mist, haze, most smoke, and some fog.

Aerosol Trade name of strong wetting agent based on sulfonated bi-carboxy-acid esters.

aerugite A grass-green to brown nickel arsenate, perhaps Ni (sub 17) As (sub 6) O (sub 32) ; an analysis gave 48.77% nickel. It is an oxidized vein mineral.

aerugo a. Copper carbonate, due to weathering of the metal; esp., the patina adhering to old bronzes. b. Copper rust; verdigris; esp., green copper rust adhering to old bronzes.

aeschynite An orthorhombic mineral, (Ce,Ca,Fe,Th)(Ti,Nb) (sub 2) (O,OH) (sub 6) ; radioactive; occurs in black sands and pegmatites.

aethiops mineral A former name for metacinnabar; isometric HgS .

aetite a. A nodule consisting of a hard shell of hydrated iron oxide within which yellow iron oxide becomes progressively softer toward the center, which may be hollow. b. See: eaglestone.

af

affinity In ion exchange, relative strength of attachment of competing ions for anchorage on a resin.

A-frame a. Two poles or legs supported in an upright position by braces or guys and used as a drill mast. b. An open structure tapering from a wide base to a narrow load-bearing top.

A-frame headgear A steel headgear consisting of two heavy plate A-frames, set astride the shaft mouth. They are braced together and carry the heavy girders that support the winding sheaves platform. It is a completely self-supporting and rigid structure that leaves usable space around the shaft collar and includes a guide-tower structure built over the shaft collar. A number of these headgears have been erected in the Republic of South Africa.

African emerald a. A deceiving name for green fluor; also for green tourmaline. b. An emerald from the Transvaal. It is usually quite yellowish green; often dark and dull. Hardness, 7.5; sp gr, 2.72 to 2.79; refractive index, 1.58 to 1.59; birefringence, 0.007. Syn: Transvaal emerald. c. A term variously used for southern African emeralds (beryl), green tourmaline, and other green gemstones from this region.

afterblast During an explosion of methane and oxygen, carbon dioxide and steam are formed. When the steam condenses to water a partial vacuum is created, which causes an inrush or what is known as an afterblast.

afterblow Continued blowing of air through Bessemer converter after flame has dropped, for removal of phosphorus in steel production.

afterbreak In mine subsidence, a movement from the sides, the material sliding inward, and following the main break, assumed to be at right angles to the plane of the seam. The amount of this movement depends on several factors, such as the dip, depth of seam, and nature of overlying materials.

afterburst a. A tremor as the ground adjusts itself to the new stress distribution caused by new underground openings. b. In underground mining, a sudden collapse of rock subsequent to a rock burst.

aftercooler A device for cooling compressed air between the compressor and the mine shaft. By cooling and dehumidifying the air, and thus reducing its volume, the capacity and efficiency of the pipeline are increased. See also: air-conditioning process; intercooler.

afterdamp The mixture of gases that remain in a mine after a mine fire or an explosion of combustible gases. It consists of carbonic acid gas, water vapor (quickly condensed), nitrogen, oxygen, carbon monoxide, and in some cases free hydrogen, but usually consists principally of carbonic acid gas and nitrogen, and is therefore irrespirable. See also: blackdamp; damp.

aftergases Gases produced by mine explosions or mine fires.

aftershock An earthquake that follows a larger earthquake or main shock and originates at or near the focus of the larger earthquake. Generally, major earthquakes are followed by many aftershocks, which decrease in frequency and magnitude with time. Such a series of aftershocks may last many days for small earthquakes or many months for large ones. CF: foreshock.

aftersliding In mine subsidence, an inward movement from the side, resulting in a pull or draw beyond the edges of the workings.

afwillite A monoclinic mineral, Ca (sub 3) Si (sub 2) O (sub 4) (OH) (sub 6) ; it is formed as portland cement is hydrated under special conditions, and where calcium silicate is autoclaved (as in sand-lime brick manufacture).

ag

agalite A fine fibrous variety of talc pseudomorphous after enstatite. Syn: asbestine.

agalmatolite A soft, waxy stone--such as pinite, pyrophyllite, or steatite--of a gray, green, yellow, or brown shade; used by the Chinese to simulate jade for carving small images, miniature pagodas, and similar objects. Syn: figure stone; pagodite; lardite; lard stone.

agardite A hexagonal mineral, (RE,Ca)Cu (sub 6) (AsO (sub 4) ) (sub 3) (OH) (sub 6) .3H (sub 2) O ; mixite group. Lanthanum, yttrium, or cerium may predominate among the rare earths.

agaric mineral a. A soft, pulverulent hydrated silicate of magnesium in Tuscany, IT, from which floating bricks can be made. b. A light, chalky deposit of calcium carbonate formed in caverns or fissures in limestone. Syn: rock milk.

agate a. A kind of silica consisting mainly of chalcedony in variegated bands or other patterns; commonly occupying vugs in volcanic and other rocks. b. A translucent cryptocrystalline variety of variegated chalcedony commonly mixed or alternating with opal and characterized by colors arranged in alternating stripes or bands, in irregular clouds, or in mosslike forms; occurs in virtually all colors, generally of low intensity, in vugs in volcanic rocks and cavities in some other rocks. CF: onyx. See also: banded agate; chalcedony; clouded agate; moss agate.

agate jasper An impure variety of agate consisting of jasper with veins of chalcedony. Syn: jaspagate.

agate opal Opalized agate.

agatized wood A variety of silicified wood which resembles any variety of agate. See: silicified wood.

age a. The formal geochronologic unit of lowest rank, below epoch, during which the rocks of the corresponding stage were formed. b. A term used informally to designate a length of geologic time during which the rocks of any stratigraphic unit were formed. c. A division of time of unspecified duration in the history of the Earth, characterized by a dominant or important type of life form; e.g., the age of mammals. d. The time during which a particular geologic event or series of events occurred or was marked by special physical conditions; e.g., the Ice Age. e. The position of anything in the geologic time scale; e.g., the rocks of Miocene age. It is often expressed in years. See also: geologic age.

Agecroft device A device placed in the rail track to arrest a forward runaway tram. The front axle of a descending tram traveling at normal speed depresses the catch and allows it to drop back in time for the back axle to pass over. Should the tram be traveling at excessive speed, the tail end of the catch arrests the rear axle.

agent a. The manager of a mining property. b. On a civil engineering contract, the responsible representative of the contractor, acting for him or her in all matters. c. Before nationalization in Great Britain, the term referred to the chief official of a large coal mine or group of mines under the same ownership. After nationalization, the equivalent term is group manager. d. A chemical added to pulp to produce desired changes in climate of the system.

age ratio The ratio of daughter to parent isotope upon which the age equation is based. For a valid age determination, (1) the isotope system must have remained closed since solidification, metamorphism, or sedimentation, (2) the decay constant must be known, and (3) the sample must be truly representative of the rock from which it is taken.

agglomerate belt flotation A coarse-fraction concentration method used in milling pebble phosphate in which conditioned feed at 70% to 75% solids is placed on a flat conveyor belt traveling at a rate of about 75 ft/min (22.9 m/min). Water sprayed on the surface of the pulp aerates the pulp, causing agglomerates of phosphate particles to float to the side of the belt for removal. The silica fraction travels the length of the belt and is permitted to flow off the opposite end. Baffles are positioned at appropriate points along the belt to stir the material so that trapped phosphate particles are given an opportunity to float. Concentrate from the first belts or rougher operation is cleaned on a second belt for further silica removal. Tailings from the cleaner belt are recycled to the rougher circuit.

agglomerate screening A coarse-fraction concentration method used in milling pebble phosphate that is based on flowing reagentized feed over a submerged sloping, stationary screen. Agglomerated phosphate particles float on top of the screen and are recovered at the lower end. Sand particles pass through the screen and are removed as a tailings fraction. Each screen section is approx. 3 ft (0.9 m) wide by 4 ft (1.2 m) long and treats 2 to 3 st/h (1.8 to 2.7 t/h) of feed.

agglomerating value A measure of the binding qualities of coal but restricted to describe the results of coke-button tests in which no inert material is heated with the coal sample. CF: agglutinating value.

agglomeration a. In beneficiation, a concentration process based on the adhesion of pulp particles to water. Loosely bonded associations of particles and bubbles are formed that are heavier than water; flowing-film gravity concentration is used to separate the agglomerates from nonagglomerated particles. Agglomeration also refers to briquetting, nodulizing, sintering, etc. b. See: kerosine flotation.

agglutinate A welded pyroclastic deposit characterized by vitric material binding the pyroclasts, or sintered vitric pyroclasts. Also spelled agglutinite.

agglutinating power See: caking index.

agglutinating value A measure of the binding qualities of a coal and an indication of its caking or coking characteristics. Applicable with reference to the ability of fused coal to combine with an inert material such as sand. CF: agglomerating value.

agglutinating-value test A laboratory test of the coking properties of coal, in which a determination is made of the strength of buttons made by coking a mixture of powdered coal and 15 to 30 times its weight of sand.

agglutination See: cementation.

aggradation a. The building up of the Earth's surface by deposition; specif., the upbuilding performed by a stream in order to establish or maintain uniformity of grade or slope. See also: gradation. CF: degradation. Syn: upgrading. b. A syn. of accretion, as in the development of a beach. The spread or growth of permafrost, under present climatic conditions, due to natural or artificial causes.

aggregate a. A mass or body of rock particles, mineral grains, or a mixture of both. b. Any of several hard, inert materials, such as sand, gravel, slag, or crushed stone, mixed with a cement or bituminous material to form concrete, mortar, or plaster, or used alone, as in railroad ballast or graded fill. The term can include rock material used as chemical or metallurgical fluxstone. See also: chippings; coarse aggregate; fine aggregate; lightweight aggregate.

aging A change in the properties of a substance with time. See also: overaging; precipitation hardening.

Agitair flotation machine Uses air to separate aerophilic and hydrophilic particles. Low-pressure air bubbles lift aerophilic particles to an overflow, leaving hydrophilic particles behind.

agitation dredging Consists of pumping the discharge directly into the sea and using the tide to carry the fines to deeper water areas. Agitation dredging is employed only during ebb tide in tidal estuaries having swift tidal flows that will disperse the accumulations of silt.

agitation ratio In older type gravity concentrators, such as tables and vanners, the ratio between the average diameter of a mineral particle and the diameter of a gangue particle that travels at equal speed.

agitator a. A tank in which very finely crushed ore is agitated with leaching solution. Usually accomplished by means of a current of compressed air passing up a central pipe and causing circulation of the contents of the tank. Sometimes called a mixer. b. A device used to stir or mix grout or drill mud. Not to be confused with shaker or shale shaker. c. A device used to bring about a continuous vigorous disturbance in a pulp; frequently used to assist bubble formation. d. Pac. See: settler.

aglaite A pseudomorph of spodumene in which the spodumene has been replaced by muscovite either as pinite or as visible plates. Also called pihlite and cymatolite in the belief that the material was a new mineral.

agmatite Migmatite with appearance of breccia. CF: contact breccia.

agnesite An early name for bismutite, Cornwall, U.K.

agonic line An isogonic line that connects points of zero magnetic declination. Its position changes according to the secular variation of the Earth's magnetic field. See also: isogonic line.

agreement The formal document by which the contractor and the authority mutually agree to comply with the requirements of the drawings, specification, schedule, conditions of tendering, and general conditions of contract and the tender. See also: tender; contract.

agricolite A former name for eulytite.

agricultural geology The application of geology to agricultural needs, e.g., mineral deposits used as fertilizers or the location of ground water. Syn: agrogeology.

agricultural lime a. Either ground quicklime or hydrated lime whose calcium and magnesium content is capable of neutralizing soil acidity. b. Lime slaked with a minimum amount of water to form calcium hydroxide.

agrite A brown, mottled calcareous stone.

agrogeology See: agricultural geology.

aguilarite An orthorhombic mineral, Ag (sub 4) SeS .