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

pachnolite
 * A monoclinic mineral, NaCaAlF (sub 6) .H (sub 2) O ; white; distinct cleavage; dimorphous with thomsenolite; an alteration of cryolite.

Pachuca tank
 * A cylindrical tank with a conical bottom. It contains a pipe that is coaxial with the leaching tank and open at both ends; compressed air is introduced at the lower end of this pipe, which behaves as an air lift. The density of the pulp within the pipe is less than that of the pulp surrounding it because of the column of air bubbles contained in the pipe, and the pressure of the denser pulp causes the pulp in the central pipe to rise and overflow, thus circulating the entire charge. Syn: Brown agitator; Brown tank. See also: Patterson agitator.

Pacific suite
 * One of two large groups of igneous rocks, characterized by calcic and calc-alkalic rocks. Harker (1909) divided all Tertiary and Holocene igneous rocks of the world into two main groups, the Atlantic suite and the Pacific suite. Because there is such a wide variation in tectonic environments and associated rock types in the areas of Harker's Atlantic and Pacific suites, the terms are now seldom used to indicate kindred rock types. CF: Mediterranean suite.

pacite
 * An iron arsenosulfide near arsenopyrite in composition.

pack
 * a. A pillar, constructed from loose stones and dirt, built in the waste area or roadside to support the roof. See also: double packing; solid stowing; strip packing.

b. A pack built on a longwall face between the gate-side packs is called an intermediate pack. c. Waste rock or timber support used for a roof over underground workings or used to fill excavations. Also called fill. d. To cause the speedy subsidence of ore in the process of washing by beating a keeve or tub with a hammer.

pack builder
 * a. Person who builds packs or pack walls. See also: pack.

b. In anthracite and bituminous coal mining, a worker who: (1) fills worked-out rooms, from which coal has been mined, with rock, slate, or other waste to prevent caving of walls and roofs; (2) builds rough walls and columns of loose stone, heavy boards, timber, or coal along haulageways and passageways and in rooms where coal is being mined, to prevent caving. Also called packer. See also: pillar man; timber packer; waller.

pack cavity system
 * See: methane drainage.

pack drawer
 * In anthracite and bituminous coal mining, a laborer who draws (tears down) stone or timber packs (pillars constructed by pack builders in the working place to support the roof during extraction of coal) to permit the roof to cave behind as the mining of the coal recedes toward the entrance of the working area.

packer
 * a. A short expansible-retractable device deliberately set in a cased or uncased well bore to prevent upward or downward fluid movement; generally for temporary use.

b. A miner employed in stowing or packing the waste area. Also called gobber.

packfong
 * Chinese. A silver-white alloy of copper, zinc, and nickel; German silver.

pack hardening
 * Case carburizing, using a solid carburized medium, followed by a hardening treatment.

pack hole
 * The space adjacent to a gate end at the face and between the face end of a gate-side pack and the coal face into which packs will be inserted when the gate is ripped or dinted.

packing
 * a. Occurs in crushing plants when the material in the chamber is so compacted as to be nearly without voids. It occurs when free downward movement is inhibited.

b. The filling of a waste area with stones and dirt. See also: solid stowing. c. The method of giving support to a roof by the insertion of waste material placed or built into space from which coal or ore has been extracted. d. The spacing or density pattern of the mineral grains in a rock. CF: fabric. e. See: blocking. f. With gyratories, packing copy refers to an accumulation of sticky fines on the diaphragm.

packing density
 * The bulk density of a granular material, when packed under specified conditions. It is commonly determined, particularly for foundry sands.

packing factor
 * Ratio of true volume to bulk volume.

packing gland
 * An explosion-proof entrance for conductors through the wall of an explosion-proof enclosure, to provide compressed packing completely surrounding the wire or cable, for not less than 1/2 in (1.27 cm) measured along the length of the cable.

packsand
 * A very fine-grained sandstone that is so loosely consolidated by a little calcareous cement as to be readily cut by a spade.

pack wall
 * A dry-stone wall built along the side of a roadway, or in the waste area, of a coal or metal mine. The wall helps to support the roof and also to retain the packing material and prevent it spreading into the roadway.

pad
 * a. Ground-contact part of a crawler-type track.

b. See: wallplate. c. The refractory brickwork below the molten iron at the base of a blast furnace.

paddle
 * a. Numbered wooden marker which shovelers put in the cans of ore that they load.

b. A straight iron tool for stirring ore in a furnace. c. A bat or pallet, as used in tempering clay. d. A scoop for stirring and mixing, as used in glassmaking.

paddle conveyor
 * See: paddle-type mixing conveyor.

paddle loader
 * A belt loader equipped with chain-driven paddles that move loose material to the belt.

paddle mixer
 * A form of worm conveyor having two noncontinuous spirals that form paddles; the shafts are contrarotating and the spirals opposite. See also: paddle-type mixing conveyor.

paddle-type mixing conveyor
 * A type of conveyor consisting of one or more parallel paddle conveyor screws. See also: blending conveyor; paddle conveyor.

paddle washer
 * A type of conveyor consisting of one or two inclined parallel paddle conveyor screws in a conveyor trough having a receiving tank and an overflow weir at the lower end and a discharge opening at the upper end.

paddle-wheel fan
 * A centrifugal fan with radial blades.

paddy
 * A borehole drill bit having cutters that expand on pressure. Also called expansion bit; paddy bit.

paddy bit
 * See: paddy.

paddy lamp
 * A portable battery-operated lamp attached to the front or rear of a personnel train.

padlock sheave
 * a. The bucket sheave on a dipper or hoe shovel.

b. A sheave set connecting inner and outer boom lines.

page
 * a. A small wooden wedge used in securing the timbering for excavations.

b. In brickmaking, a track carrying the pallets bearing newly molded bricks.

pagodite
 * Ordinary massive pinite in its amorphous compact texture and other physical characters, but containing more silica. The Chinese carve the soft stone into miniature pagodas and images. See also: agalmatolite; lardite; pinite.

Pahrump
 * A provincial series of the Precambrian in California.

paint
 * a. A term used in the western United States for an earthy, pulverulent variety of cinnabar.

b. A film of molybdenite in fractures and veinlets.

paint gold
 * A very thin coating of gold on minerals.

painting
 * The painting of the mine roof with a coal-tar paint that seals the bottom strata of the roof to prevent air from entering the crevices of the roof.

paint mill
 * A machine for grinding mineral paints.

paint rock
 * A soft, incompetent, fine-grained mass of quartz, pyrolusite, and kaolin with subangular fragments of chert, hematite, and goethite.

paint-rock ore
 * See: natural ore.

pair
 * A party of co-workers; a gang. Also spelled pare.

pair production
 * The transformation of a high-energy gamma ray into a pair of particles (an electron and a positron) during its passage through matter.

palagonite
 * Devitrified basaltic glass.

palasome
 * The host rock or mineral in a replacement deposit.

pale brick
 * Brick that is underfired.

paleo-
 * a. A combining form denoting great age or remoteness in regard to time (Paleozoic), or involving ancient conditions (paleoclimate). Sometimes given as pale- (palevent). Also spelled: palaeo; palaio-.

b. A prefix indicating pre-Tertiary origin, and generally altered character, of a rock to the name of which it is added, such as paleopicrite; by some the prefix has been applied to pre-Carboniferous rocks or features, such as the PaleoAtlantic Ocean.

paleobotany
 * The study of plants of past geological ages through the investigation of fossils. CF: paleontology; palynology.

paleoclimatology
 * The branch of science that treats of climatological conditions during the history of the Earth.

paleocurrent
 * A current, generally of water, that influenced sedimentation or other processes or conditions in the geologic past.

paleoecology
 * The science of the relationship between ancient organisms and their environments.

paleogeography
 * a. The study and description of the physical geography of the geologic past, such as the historical reconstruction of the pattern of the Earth's surface or of a given area at a particular time in the geologic past, or the study of the successive changes of surface relief during geologic time.

b. The study of the relative positions of land masses as part of tectonic reconstructions of Earth history.

paleogeologic map
 * A map that shows the areal geology of an ancient surface at some time in the geologic past; esp. such a map of the surface immediately below an unconformity, showing the geology as it existed at the time the surface of unconformity was completed but before the overlapping strata were deposited. Paleogeologic maps were introduced by Levorsen (1933).

paleolithologic map
 * A paleogeologic map that shows lithologic variations at some buried horizon or within some restricted zone at a particular time in the geologic past.

paleomagnetism
 * Faint magnetic polarization of rocks that may have been preserved since the accumulation of sediment or the solidification of magma whose magnetic particles were oriented with respect to the Earth's magnetic field as it existed at that time and place.

paleontological facies
 * a. The paleontological aspect of a particular sedimentary lithology; e.g., nummulitic facies, crinoid facies, etc.

b. Sedimentary facies differentiated on the basis of fossils.

paleontologist
 * Person who studies the fossilized remains of animals and/or plants.

paleontology
 * A science that deals with the life of past geological periods, based on the study of fossil remains of plants and animals, and gives information esp. about the phylogeny and relationships of modern animals and plants and about the chronology of the history of the Earth. CF: paleobotany; paleoclimatology; paleogeography.

paleozoology
 * That branch of paleontology dealing with the study of fossil animals, both invertebrate and vertebrate.

palimpsest
 * Said of a structure or texture of metamorphic rocks in which remnants of some pre-existing structure or texture are preserved.

palingenesis
 * Formation of a new magma by the melting of pre-existing magmatic rock in situ. Considered incorrectly by some workers as a syn. of anatexis. Adj: palingenic.

palladinite
 * A poorly defined ocherous coating on palladian gold, probably PdO.

palladium
 * A soft, ductile, steel-white metallic element of the platinum group metals. Symbol, Pd. Found along with platinum and other metals of the platinum group in placer deposits; also found associated with nickel-copper deposits. Used as a catalyst, in dentistry, watchmaking, surgical instruments, and electrical contacts.

palladium amalgam
 * A former name for potarite. See also: potarite.

palladium gold
 * Same as porpezite, or gold, containing palladium up to 10%. See also porpezite; gold.

pallas iron
 * See: pallasite.

pallasite
 * a. Any ultramafic rock, whether of meteoric or terrestrial origin, that contains approx. 60% iron if meteoric, or more iron oxides than silica if terrestrial.

b. A stony-iron meteorite composed essentially of large single glassy crystals of olivine embedded in a network of nickel-iron. Pallasites are believed to have been formed at the interface of the stony mantle and metal core of a layered planetoid. Syn: pallas iron.

palleting
 * A light platform in the bottom of powder magazines to preserve the powder from dampness.

pallet molding
 * A method of forming bricks in sanded molds, from which they are dumped on a board called a pallet.

pallet-type conveyor
 * A series of flat or shaped wheelless carriers propelled by and attached to one or more endless chains or other linkage.

Palo-Travis analyser
 * A sedimentation apparatus for determining particle size, based upon the settling of powder through a long sedimentation tube filled with liquid. The instrument consists of the sedimentation tube, a smaller reservoir at the top joined to the tube through a large bore stopcock, and a calibrated capillary mounted concentrically at the bottom of the tube.

paludal
 * Pertaining to swamps or marshes, and to organic, clay, or other material deposited in a swamp environment. CF: palustrine.

paludification
 * Process of formation of a peat bog. This requires a steady growth of new peat-forming plants in phase with a steady general sinking of the depression in which this occurs.

palustrine
 * Pertaining to material deposited in a swamp or marsh environment. CF: paludal.

palygorskite
 * a. A monoclinic and orthorhombic mineral, (OH) (sub 2) (Mg,Al) (sub 4) (Si,Al) (sub 8) O (sub 20) .8H (sub 2) O ; fibrous; in desert soils.

b. A general name for lightweight fibrous clay minerals showing significant substitution of aluminum for magnesium; characterized by distinctive rodlike shapes under an electron microscope. Syn: attapulgite.

palynology
 * a. A branch of science concerned with the study of pollen of seed plants and spores of other embryophytic plants, whether living or fossil, including their dispersal and applications in stratigraphy and paleoecology.

b. The study of the fossilized spores and pollen grains of the plants, esp. those whose remains contributed to the formation of coal seams. CF: paleobotany; paleontology.

pan
 * a. A shallow steel or porcelain dish in which drillers or samplers wash drill sludge to a gravity concentrate and separate the particles of heavy minerals from the lighter-density rock powder to ascertain if the rocks traversed by the borehole contain minerals of value. Syn: tin dish.

b. Hardpan. c. Fireclay or underclay of coal seams. d. A trough or section of a pan conveyor or shaker conveyor. e. The framework of a belt or chain conveyor. See also: tray. f. A circular steel dish from 10 to 16 in (25 to 40 cm) in diameter at the top, from 2 to 2-1/2 in (5.1 to 6.4 cm) deep, and with sides sloping at 35 degrees to 40 degrees to the horizontal, used for testing and working placer deposits. Syn: batea; miner's pan; prospecting pan; gold pan. CF: dish. g. A carrying scraper. h. See: panning.

panabase
 * See: tetrahedrite.

panabasite
 * A former name for tetrahedrite. See also: tetrahedrite.

pan amalgamation
 * See pan-amalgamation process.

pan-amalgamation process
 * Method of recovering silver and gold from their ores, in which a cast iron pan or barrel is used for contacting a slurry of the crushed ore with salt, copper sulfate, and mercury; the released silver and gold form an amalgam with the mercury. Syn: pan amalgamation.

Pan-American jig
 * Mineral jig developed for treatment of alluvial sands.

pancake
 * a. See: ribbon.

b. Any of concrete discs that are stacked to form concrete columns for stope support. They are cast at the surface and are usually 30 in (76.2 cm) diameter by 4 in (10.2 cm) thick with reinforcement from wire rope.

panclastite
 * An explosive composed of liquid nitrogen tetroxide mixed with carbon disulfide or other liquid combustible, in the proportion of three volumes of the former to two of the combustible.

pan conveyor
 * a. A conveyor comprising one or more endless chains or other linkage to which usually overlapping or interlocking pans are attached to form a series of shallow, open-topped containers. Some pan conveyors have been known also as apron conveyors.

b. Jigging conveyor; a trough down which coal slides after mining and loading in dipping seams, with motion being aided by a shaking action. See also: jigger. c. A trough conveyor or gravity conveyor.

pandermite
 * a. See: priceite.

b. A name for firm, compact, porcelainlike masses of colemanite.

pan-edge
 * a. A runner mill for grinding or mixing granular material.

b. Steel supporting plates on which furnace bottom refractories are placed.

panel
 * a. A large rectangular block or pillar of coal.

b. A method of working whereby the workings of a mine are divided into sections, each surrounded by solid strata and coal with only necessary roads through the coal barrier. Also spelled pannel. c. The working of coal seams in separate panels or districts; e.g., single unit panel. See also: panel working. d. Rectangle of lode ore that is defined by means of levels and winzes and then considered to be proved as regards volume for valuation purposes. e. A group of breasts or rooms separated from the other workings by large pillars. f. A small portion of coal left uncut.

panel barrier
 * The pillar of coal left between the adjacent panels. These pillars are often worked on the retreat after the coal in the panels has been extracted. In the panel system of bord-and-pillar mining, the panel barrier may be 22 yd (20 m) (minimum) wide and about 300 yd (274 m) apart. In longwall panel mining, the barriers may be made of sufficient width for extraction by a conveyor face on the retreat. Also called panel pillar. See also: Bolsover experiment.

panel slicing
 * a. In stoping, the process of mining out a panel either from above, below, or one side as described by a qualifying term.

b. See: top slicing and cover caving.

panel working
 * a. Working laid out in districts or panels, which are then extracted as single units. The panel system of working may be adopted with pillar-and-stall and longwall methods. See also: pillar methods of working.

b. A system of working coal seams in which the colliery is divided up into large squares or panels isolated or surrounded by solid ribs of coal of which a separate set of breasts and pillars is worked, and the ventilation is kept distinct; i.e., every panel has its own circulation, the air of one not passing into the adjoining one, but being carried direct to the main return airway.

pan feeder
 * See: conveyor-type feeder.

pan-feeder operator
 * See: mill feeder.

panhead
 * A head to a rivet or screw having the shape of a truncated cone.

panidiomorphic
 * A textural term for rocks in which all or almost all of the mineral constituents are idiomorphic or euhedral.

panman
 * a. A worker who places in position and tends the operation of underground trough conveyors for the transportation of coal or other minerals. These conveyors are built in sections, and the principal task of the panman is to move the sections from one position to another.

b. One engaged in dismantling or building conveyors. Also called panner.

panning
 * A technique of prospecting for heavy metals, such as gold, by washing placer or crushed vein material in a pan. The lighter fractions are washed away, leaving the heavy metals behind in the pan. See also: pan.

pantellerite
 * A peralkaline rhyolite or quartz trachyte with normative quartz exceeding 10%. It is more mafic than comendite.

pantograph
 * a. A type of drawing instrument consisting of rods linked together in the form of a parallelogram, used for copying a drawing to any required scale.

b. The hinged diamond-shaped structure mounted on the roof of an electric locomotive to collect electric power from an overhead wire.

pan-type car
 * Doorless car of two-way, side-dump design; built in capacities from 4 to 10 yd (super 3) (3.1 to 7.6 m (super 3) ). The car body is reversible and may be dumped to either side. Dumping is accomplished by means of an external hoist at the dumping point.

Panzer conveyor
 * See: armored flexible conveyor.

Panzer-Forderer snaking conveyor
 * A very strong, armored conveyor that is moved forward behind a coal plow by means of a traveling wedge pulled along by the plow or by means of jacks or compressed-air-operated rams attached at intervals to the conveyor structure.

papa
 * a. A bluish white, massive New Zealand clay like pipe clay; used for whitening fireplaces. When hard, it is called papa rock. Etymol: Polynesian.

b. Sp. A nugget of gold or silver. c. A nodule of mineral.

papagoite
 * A monoclinic mineral, CaCuAlSi (sub 2) O (sub 6) (OH) (sub 3) ; forms blue crystals; secondary; at Ajo, Pima County, AZ.

paper clay
 * A fine-grained, white, kaolinic clay with high retention and suspending properties, high reflectance, and a very low content of free silica. It is used for coating or filling paper.

paper coal
 * a. Coal in which cuticular matter may be prominent.

b. A variety of brown coal deposited in thin layers like sheets of paper.

paper shale
 * A shale that easily separates on weathering into thin layers or laminae suggesting sheets of paper; it is often highly carbonaceous.

paper spar
 * A crystallized variety of calcite found in thin lamellae or paperlike plates.

par-
 * See: para-.

para-
 * a. A prefix applied to the names of metamorpic rocks that have been derived from sediments; e.g., paragneiss.

b. Prefix meaning beside or nearby. c. Indicating a polymorph. d. Indicating a schist or gneiss derived from a sedimentary protolith. e. A matrix-rich clastic sedimentary rock. f. In chemistry, a prefix indicating: (1) an isomeric or polymeric modification; such as paracyanogen, paraldehyde, etc.; (2) a modification or a similar compound that is not necessarily isomeric or polymeric; such as, paramorphine; (3) a benzene diderivative in which the substituted atoms or radicals are directly opposite each other on the benzene ring--i.e., occupying the positions 1 and 4--such as paraxylene; or (4) an inactive isomer produced by a combination of its dextro- and levo- modifications--such as, paratartaric acid. A Greek prefix meaning beside. Abbrev., p-. Syn: par-. g. A Greek prefix meaning beside. In the name of a metamorphic rock, such as paragneiss, it means derived from an original sediment.

parabola
 * The shape taken by the curve of a bending moment diagram for a uniformly distributed load on a beam simply supported.

parabutlerite
 * An orthorhombic mineral, Fe (super 3+) (SO (sub 4) )(OH).2H (sub 2) O ; dimorphous with butlerite: orange; an alteration product of copiapite.

paracelsian
 * A monoclinic mineral, BaAl (sub 2) Si (sub 2) O (sub 8) ; feldspar group; pale yellow; dimorphous with celsian; at Candoglia, Italy. Syn: barium feldspar.

parachrosis
 * Discoloration in minerals from exposure to weather.

paraconformity
 * An unconformity at which strata are parallel and the contact is a simple bedding plane.

paraconglomerate
 * A term proposed by Pettijohn (1957) for a conglomerate that is not a product of normal aqueous flow, but is deposited by such agents as subaqueous turbidity slides and glacier ice; it contains more matrix than gravel-sized fragments (pebbles may form less than 10% of the rock). Examples include tillites, pebbly mudstones, and relatively structureless clay or shale bodies in which pebbles or cobbles are randomly distributed. Syn: conglomerate mudstone.

paracoquimbite
 * A trigonal mineral, Fe (super 3+) (sub 2) (SO (sub 4) ) (sub 3) .9H (sub 2) O ; dimorphous with coquimbite; pale violet; astringent tasting; secondary; in oxidized iron sulfide deposits.

paradamite
 * A triclinic mineral, Zn (sub 2) (AsO (sub 4) )(OH) ; rare; dimorphous with adamite and isomorphous with tarbuttite; transparent; vitreous; pale yellow; forms sheaflike aggregates and striated equant crystals; at the Ojuela Mine, Durango, Mexico.

paraffin shale
 * See: oil shale.

paragenesis
 * A characteristic association or occurrence of minerals or mineral assemblages in ore deposits, connoting contemporaneous formation. CF: mineral sequence.

paragenetic
 * a. Pertaining to paragenesis.

b. Pertaining to the genetic relations of sediments in laterally continuous and equivalent facies.

paragneiss
 * In petrology, a gneiss formed by the metamorphism of a sedimentary rock. CF: orthogneiss.

Paragon
 * Trade name for a nonrotating rope of 12 by 6 over 3 by 24 strand construction.

paragonite
 * A monoclinic mineral, NaAl (sub 2) (AlSi (sub 3) )O (sub 10) (OH) (sub 2); mica group; pseudohexagonal with basal cleavage; forms fine-grained, massive, scaly aggregates; occurs in metamorphic rocks and in soils; not common as it is incompatible with potassium feldspar (albite plus muscovite is more stable); rarely identified because of its similarity to muscovite. Syn: soda mica.

paragonite schist
 * A variety of schist in which paragonite supplants muscovite or biotite.

paraguanajuatite
 * A trigonal mineral, Bi (sub 2) (Se,S) (sub 3) ; paramorphous after orthorhombic guanajuatite.

parahilgardite
 * A mineral trimorphous with monoclinic hilgardite and triclinic hilgardite. See also: hilgardite.

parahopeite
 * A colorless hydrous zinc phosphate, Zn (sub 3) (PO (sub 4) ) (sub 2) .4H (sub 2) O, triclinic. Minute tabular or prismatic crystals; fan-shaped aggregates. From Broken Hill, Northern Rhodesia; Salmo, BC.

parajamesonite
 * An orthorhombic mineral, Pb (sub 4) FeSb (sub 6) S (sub 14) ; dimorphous with jamesonite; metallic; black; distinguished by its X-ray pattern.

paralaurionite
 * A monoclinic mineral, PbCl(OH); dimorphous with laurionite; soft; forms white pseudo-orthorhombic prismatic crystals; a secondary mineral in lead deposits.

paralic
 * Said of deposits laid down on the landward side of a coast, in shallow fresh water subject to marine invasions. Thus, marine and nonmarine sediments are interbedded; as exemplified in the lower part of the Coal Measures, the nonmarine (paralic) predominate, with relatively thin marine bands. CF: limnic.

paralic coal basin
 * A coal basin that originated near the sea--as opposed to a limnic coal basin.

parallax
 * a. In survey work, incorrect reading of a graduation on an instrument if the observer's eye is not truly normal to the graduated plate.

b. The change in bearing or apparent position of an object produced by a change in the observer's position. c. The apparent displacement, or change in position, of the crosshairs of a focusing telescope with reference to the image of an object, as the eye is moved from side to side, when the focus of the eyepiece or objective is imperfect.

parallel blasting circuit
 * An electric blasting circuit in which the leg wires of each detonator are connected across the firing line directly or in parallel through bus wires. Syn: series-in-parallel circuit. CF: loop circuit.

parallel circuit firing
 * A method of connecting together a number of detonators that are to be fired electrically in one blast. The electric detonators are connected to two common points. Each detonator offers a path for the electric current, independent of all the other detonators in the circuit, and therefore calls for a higher amperage than a series circuit in which there is but one path.

parallel cut
 * Group of parallel holes, not all charged with explosive, that creates the initial cavity to which the loaded holes break in blasting a development round.

parallel displacement fault
 * A fault along which all straight lines on opposite sides of the fault and outside the dislocated zone that were parallel before the displacement are parallel afterward.

parallel drum
 * A cylindrical form of drum on which the haulage or winding rope is coiled. The drum roll may be plain or grooved. For deep winds, multilayering of rope is often used to reduce the drum size required. Also, for deep winding (3,000 ft or 915 m or more), a balance rope is almost essential with a parallel drum. Syn: cylindrical drum. See also: winding drum.

parallel duplex mine cable
 * See: portable parallel duplex mine cable.

parallel entry
 * Usually an intake airway parallel to the haulageway.

parallel extinction
 * In mineral optics, refers to crystal edges or cleavage traces parallel to the optic directions of the mineral. CF: extinction.

parallel firing
 * The firing of detonators in a round of shots by dividing the total supply current between the individual detonators. CF: series firing.

parallel flow
 * Flow in the same direction of two or more streams within a stream system.

parallel fold
 * A fold in which beds maintain the same thicknesses throughout. CF: similar fold; supratenuous fold. Syn: concentric fold.

parallel growth
 * Two or more crystals with corresponding faces parallel.

parallel lines
 * Lines that lie in the same plane and are equally distant from each other at all points. The term is ordinarily applied to straight lines.

parallelogram
 * Quadrilateral that has opposite sides parallel and opposite angles equal.

parallel ripple mark
 * A ripple mark with a relatively straight crest and an asymmetric profile; specif. a current ripple mark.

parallel series
 * Two or more series of electric blasting caps arranged in parallel. See also: multiple series.

parallel series circuit
 * A method of connecting together a number of detonators to be fired electrically in one blast. The circuit consists of a number of series circuits connected in parallel. Syn: series-in-parallel circuit.

parallel unconformity
 * See: disconformity.

parallel wire method
 * An electrical prospecting method using equipotential lines or curves in prospecting for orebodies. In the parallel wire method, two bare copper wires about 3,000 ft (915 m) long, placed about 2,000 ft (610 m) or more apart, are used as electrodes. Current is supplied from the generator, and the electrodes are connected to the ground at 100 ft (30 m) intervals by iron grounding pins. Equipotential lines are located by two electrodes or wooden rods, to one end of which are fastened metal spikes about 6 to 7 in (15 to 18 cm) long. The electrodes are connected by some 150 ft (46 m) of wire that runs down the rods to the spikes. If a head telephone is placed in the circuit, the absence of sound in the telephone indicates that the two electrodes are at the same potential. By this method, the equipotential lines can be traced.

paramagnetic
 * Having a small positive magnetic susceptibility. A paramagnetic mineral such as olivine, pyroxene, or biotite contains magnetic ions that tend to align along an applied magnetic field but do not have a spontaneous magnetic order. CF: diamagnetic.

paramagnetism
 * a. The magnetism of a paramagnetic substance. The property by which the north pole of a magnet that is magnetized by induction is repelled to 180 degrees by the north pole of the inducing magnet.

b. The property possessed by a substance of producing a higher concentration of magnetic lines of force within itself than in the surrounding magnetic field when it is placed in such a field. c. A property of many substances, related to ferromagnetism, by virtue of which, when placed in a nonuniform magnetic field, they tend to move toward the strongest part. Permanent magnetism is practically absent and the susceptibility, which is much less than that of iron, is constant at any given temperature, but in most substances it is nearly inversely proportional to the absolute temperature. CF: ferrimagnetism; diamagnetism.

paramelaconite
 * A tetragonal mineral, Cu (super ) (super +) (sub 2) Cu (super 2+) (sub 2) O (sub 3) (sub ) ; purplish black; at Bisbee, AZ.

parameter
 * a. A constant or variable in a mathematical expression that distinguishes various specific situations.

b. In crystallography, one of the three non-coplanar vectors which describe a lattice. Syn: lattice parameter.

paramontroseite
 * An orthorhombic mineral, VO (sub 2) ; forms by loss of hydrogen and iron from montroseite in an initial stage of oxidation of uranium-vanadium deposits.

paramorph
 * A pseudomorph with the same composition as the original crystal, caused by a phase transformation; e.g., calcite with aragonite morphology. CF: pseudomorph.

paramorphism
 * a. The alteration of one mineral into another without change of composition, such as augite into hornblende in uralitization.

b. With metamorphism, it describes such thorough changes in a rock that its old components are destroyed and new ones are built up. See also: allomorphism.

paramoudra
 * Large flint nodule. See also: potstone.

pararammelsbergite
 * An orthorhombic mineral, NiAs (sub 2) ; loellingite group; trimorphous with rammelsbergite and krutovite; metallic tin-white; commonly massive.

pararealgar
 * A monoclinic mineral, AsS ; trimorphous with realgar and alpha-AsS; powdery; bright yellow to orange-brown; easily mistaken for orpiment.

paraschist
 * A schist derived from a sedimentary rock. See also: orthoschist; schist.

paraschoepite
 * An orthorhombic mineral, UO (sub 3) .(2-x)H (sub 2) O ; bright yellow; a dehydration product of schoepite. Formerly called schoepite III. See also: schoepite.

parasymplesite
 * A monoclinic mineral, Fe (super 2+) (sub 3) (AsO (sub 4) ) (sub 2) .8H (sub 2) O ; vivianite group; dimorphous with symplesite and isomorphous with koettigite; bluish green.

paratacamite
 * A trigonal mineral, Cu (sub 2) (OH) (sub 3) Cl ; forms twinned rhombohedra; massive or powdery; green to green-black; a secondary mineral in copper deposits.

paratellurite
 * A tetragonal mineral, TeO (sub 2) ; rutile group; soft; waxy; gray-white; dimorphous with tellurite; at Cananea, Mexico.

paratomous
 * Having planes of cleavage inclined to the axis; also, abounding with facets of cleavage.

parautochthonous granite
 * A mobilized portion of an autochthonous granite that has moved higher in the crust or, more usually, into tectonic domains of lower pressure. It shows variable marginal relations, in some places migmatitic in others characterized by a thermal aureole.

paravauxite
 * (sub 2) O ; colorless; forms small prismatic crystals; at Llallagua, Bolivia.

parbigite
 * See: messelite.

pargasite
 * A monoclinic mineral, NaCa (sub 2) (Mg,Fe) (sub 4) Al(Si (sub 6) Al (sub 2) )O (sub 22) (OH) (sub 2) ; amphibole group; prismatic cleavage; occurs in dolomitic marbles and in skarns.

Parian marble
 * One of the most famous of ancient statuary marbles; from the island of Paros, Greece.

parisite
 * A trigonal mineral, 6[(Ce,La,Nd) (sub 2) CaCO (sub 3) ) (sub 3) F (sub 2) ] ; vitreous to resinous; forms acute hexagonal bipyramids; in veins, such as the emerald deposits of Columbia; also in alkalic pegmatites. Named for J.J. Paris.

parkerite
 * A monoclinic mineral, Ni (sub 3) (Bi,Pb) (sub 2) S (sub 2) ; metallic; bronze; has three cleavages; in a magmatic sulfide deposit, Insizwa, South Africa.

Parkerizing
 * Treatment of steel in hot aqueous solution of free phosphoric acid and manganese dihydrogen phosphate, other salts sometimes being used as accelerators. A fine-grained insoluble film of ferric phosphate is formed in a few minutes, which is corrosion resistant.

Parker process
 * A method for producing low-temperature coke in which each retort is a monobloc iron casting 9 ft (2.7 m) high, containing 12 tubes, which taper from 4-1/2 in (11.4 cm) at the top to 5-1/4 in (13.3 cm) at the bottom. A battery contains 36 retorts in 2 rows of 18. Retorts and combustion chambers are arranged alternately, so that each retort is located in a radiation chamber formed by the walls of adjacent combustion chambers. The retorts are heated only by radiation from these walls, so that there is no overheating and the inside temperature of the retorts can be maintained accurately at 1,112 degrees F (600 degrees C). A cooling chamber is fitted below each pair of retorts, of a size sufficient to hold the coke from both. The pairs of retorts are charged and discharged every 4 h. Syn: Coalite process.

Parkes process
 * A process used to recover precious metals from lead. It is based on the principle that if 1% to 2% of zinc is stirred into molten lead, a compound of zinc with gold and silver separates out and can be skimmed off.

parmalee wrench
 * A wrench that has a smooth segmented sleeve that when tightly clamped around the tube of a core barrel, will not mar or distort the thin tube when the core barrel is taken apart.

parral agitator
 * An agitator using a number of small airlifts disposed about a circular, flat-bottomed tank in such a way as to impart a circular swirling motion to the pulp.

Parr formula
 * The simplest method for determining the amount of mineral matter present in a coal is to determine the ash and sulfur contents and to make corrections for the changes taking place in these during combustion. The Parr formula for doing this is: total inorganic matter=moisture+1.08 ash+0.55 sulfur, where moisture, ash, and sulfur represent the percentages of these substances found by analysis of the coal.

Parrish arm
 * Long arm made of a flexible board for the suspension of a shaker screen.

Parrish shaker
 * A screening shaker with flexible wooden hangers and flexible drive arms; used for sizing anthracite.

Parr's classification of coal
 * A classification system based on the proximate analysis and calorific value of ash-free, dry coal. The heating value of raw coal is obtained, and from these data a table is drawn up, at one end of which are the celluloses and woods of about 7,000 Btu/lb (16.3 MJ/kg). These data are then plotted against the percentage volatile matter in unit coal.

parsonsite
 * A triclinic mineral, Pb (sub 2) (UO (sub 2) )(PO (sub 4) ) (sub 2) .2H (sub 2) O ; forms pale citron-yellow crusts, powders, and tiny laths; nonfluorescent; radioactive; a secondary mineral in uraniferous pegmatites and other uranium deposits.

part
 * In founding, a section of a mold or flask specif. distinguished (in a three-part flask) as top part, middle part, and bottom part.

part 90 miner
 * A miner employed at an underground coal mine or at a surface work area of an underground coal mine who has exercised the option under the old section 203b program (36 FR 20601, October 27, 1971), or under 90.3 (Part 90 option; notice of eligibility; exercise of option) of this part to work in an area of a mine where the average concentration of respirable dust in the mine atmosphere during each shift to which that miner is exposed is continuously maintained at or below 1.0 mg/m (super 3) of air, and who has not waived these rights.

part-face blast
 * Either of two stages of blasts when the height of the rock face is too great to blast in one operation.

partially fixed
 * An end support to a beam or a column that cannot develop the full fixing moment.

partial melting
 * a. Melting of part of a rock; because a rock is composed of different minerals, each with its own melting behavior, melting does not take place at one temperature (as for ice at 0 degrees C) but takes place over a range of temperatures; melting starts at the solidus temperature and continues, nonlinearly, as the temperature increases to the liquidus temperature when the rock is totally molten.

b. A situation in which only certain minerals in a rock are melted, due to their lower melting temperature.

partial pressure
 * a. That part of the total pressure of a mixture of gases contributed by one of the constituents.

b. See: Dalton's law.

partial pyritic smelting
 * Blast furnace smelting of copper ores in which some of the heat is provided by oxidation of iron sulfide and some by combustion of coke. See also: pyritic smelting.

partial roasting
 * Roasting carried out to eliminate some but not all of the sulfur in an ore.

partial subsidence
 * Any amount of subsidence that is less than full subsidence; such as with solid or strip packing.

particle
 * A general term, used without restriction as to shape, composition, or internal structure, for a separable or distinct unit in a rock; e.g., a sediment particle, such as a fragment or a grain, usually consisting of a mineral.

particle diameter
 * The length of a straight line through the center of a sedimentary particle considered as a sphere; a common expression of particle size. See also: particle size.

particle mean size
 * See: particle size.

particle size
 * The general dimensions (such as average diameter or volume) of the particles in a sediment or rock, or of the grains of a particular mineral that make up a sediment or rock, based on the premise that the particles are spheres or that the measurements made can be expressed as diameters of equivalent spheres. It is commonly measured by sieving, by calculating settling velocities, or by determining areas of microscopic images. See also: particle diameter. Syn: grain size.

particle-size analysis
 * Determination of the statistical proportions or distribution of particles of defined size fractions of a soil, sediment, or rock; specif. mechanical analysis. Syn: size analysis. See also: wet analysis.

particle-size distribution
 * The percentage, usually by weight and sometimes by number or count, of particles in each size fraction into which a powdered sample of a soil, sediment, or rock has been classified--such as the percentage of sand retained on each sieve in a given size range. It is the result of a particle-size analysis. Syn: size distribution; size-frequency distribution.

particle-size reduction
 * The process of crushing or grinding material to reduce the particle size.

particle sorting
 * Separation of solid particles, in a fluid (air, water, etc.), because of different densities or masses.

particle velocity
 * A measure of the intensity of ground vibration generated from a blasting event, specif. the time rate of change of the amplitude of ground displacement, given in inches (or millimeters) per second.

particulate
 * Refers to particles collected by filtration from ambient air.

parting
 * a. A lamina or very thin sedimentary layer separating thicker strata of a different type; e.g., a thin layer of shale or slate in a coal bed, or a shale break in sandstone. Strata tend to separate readily at partings. CF: band.

b. A small joint in coal or rock, or a layer of rock in a coal seam. See also: back. c. The physical property of some specimens of mineral species to break along specific crystallographic planes because of twinning or chemical alteration along them; e.g., rhombohedral parting in corundum. CF: cleavage; fracture. Syn: mineral parting. d. Cutting simultaneously along two parallel lines or along two lines which balance each other in the matter of side thrust. e. The final process after cupellation to remove the silver from bullion bead. f. A side track or turnout in a haulage road on which empty or loaded cars are collected for distribution to points for loading or for haulage to the surface or to the shaft or slope bottom for hoisting.

parting and connection man
 * In bituminous coal mining, a laborer who directs the movement of mine cars from a parting (a side track). Also called connection man; parting boy. See also: parting.

parting boy
 * See: parting and connection man.

parting cleaner
 * In bituminous coal mining, one who only picks out seam partings (layers of rock) in the coal working face prior to blasting, using a long-handled pick.

parting density
 * Density maintained in the bath in dense media separation.

parting flask
 * A flask used to separate gold and silver, such as by quartation, in assaying procedures. Syn: parting glass.

parting glass
 * See: parting flask.

parting liquid
 * Any of several liquids--such as tetrabromethane, ethylene dibromide, pentachlorethane, and trichlorethylene--that are used in the DuPont mineral separation process. See also: DuPont process.

parting powder
 * A powder made from chalk, bone meal, or similar nonsiliceous material, suitably waterproofed, which is applied to a pattern to ensure a clean strip from the molding sand.

parting slate
 * A term applied to a thin layer of slate between two seams of coal.

partition curve
 * A curve indicating, for each specific gravity (or size) fraction, the percentage that is contained in one of the products of the separation; e.g., the reject. Syn: distribution curve.

partition density
 * The density corresponding to 50% recovery as read from a partition curve. Syn: tromp cut point.

partition factor
 * The percentage of a specific gravity (or size) fraction recovered in one of the products of the separation; e.g., the reject. Syn: distribution factor.

partitioning method
 * A resistivity method in which a special electrode configuration is used, consisting of five electrodes, instead of the usual number of four, to provide a check on the observations.

partition size
 * The separation size corresponding to 50% recovery as read from a size partition curve.

partly filled stope
 * See: square-set stoping.

parts of line
 * Separate strands of the same rope or cable used to connect two sets of sheaves.

part-swing shovel
 * A power shovel in which the upper works can rotate through only part of a circle.

party chief
 * In seismic prospecting, the person who supervises the personnel of the crew and generally is in charge of interpretation of the data.

party foreman
 * In seismic prospecting, the person who supervises the work of a field party. Subordinate to a nonresident party chief who is responsible for the interpretation of the data.

party manager
 * a. In seismic prospecting, this person's function is to handle the operational phases of the work, particularly those involving logistics and access in difficult or remote areas, giving the party chief more time for interpretation of the data.

b. In gravity and magnetic prospecting, the person in charge of the operations of a field party.

Pasadenian orogeny
 * Mid-Pleistocene diastrophism.

Pascal's law
 * The component of the pressure in a fluid in equilbrium that is due to forces externally applied is uniform throughout the fluid.

pascoite
 * A monoclinic mineral, Ca (sub 3) V (sub 10) O (sub 28) .17H (sub 2) O ; forms yellow-orange to dark red-orange crusts and tiny laths; a secondary vanadium mineral in uranium-vanadium deposits of the Colorado Plateau, and at Minasragra, Peru.

pass
 * a. An inclined opening in a mine, a raise or a winze, through which coal or ore is delivered from a higher to a lower level. At the lower end, the pass is normally provided with a chute or hydraulic gate through which the material is discharged into cars or trams. See also: chute.

b. A raise or winze for workers to travel in from one level to another. c. The running of a sample through a sample divider. d. In surface mining, a complete excavator cycle in removing overburden.

passage
 * a. A cavern opening or underground tunnel having greater length than height or width; large enough for human entrance and larger by comparison than a lead.

b. See: pass.

passby
 * a. The double-track part of any single-track system of transport.

b. A siding in which cars pass one another underground; a turnout.

passing boss
 * See: motor boss.

passing point
 * a. On haulage roads, the point at which the loaded trams going outby pass the empty trams going inby.

b. In shafts, the point at which the loaded ascending cage or skip passes the empty descending cage or skip.

passing track
 * A sidetrack with switches at both ends.

passivation
 * The changing of the chemically active surface of a metal to a much less reactive state. CF: activation.

passivator
 * A type of inhibitor that changes the electrode potential of a metal, causing it to become more cathodic or electropositive.

passive coefficient of earth pressure
 * The maximum ratio of the major principal stress to the minor principal stress. This is applicable where the soil has been compressed sufficiently to develop an upper limiting value of the major principal stress.

passive earth pressure
 * The maximum value of lateral earth pressure exerted by soil on a structure, occurring when the soil is compressed laterally, causing its internal shearing resistance along a potential failure surface to be completely mobilized; the maximum resistance of a vertical earth face to deformation by a horizontal force. CF: active earth pressure.

passive fault
 * Fault not liable to further movement. CF: active fault.

passive metal
 * A metal on which an oxide film that prevents further attack on the metal is readily formed. When a metal other than a noble metal has a high resistance to corrosion, it is because of passivity; e.g., chromium, nickel aluminum, tin, and various alloys. See also: passivity.

passive state of plastic equilibrium
 * Plastic equilibrium obtained by a compression of a mass.

passive transducer
 * A transducer whose output waves are independent of any sources of power controlled by the actuating waves.

passivity
 * a. A metal that is normally active according to its position in the electromotive-force series is said to be passive whenever its electrochemical behavior is that of a less active metal.

b. A metal is passive when it is relatively resistant to corrosion in an environment in which a large decrease in free energy is associated with the corrosion reaction. c. A condition in which a piece of metal, because of an impervious covering of oxide or other compound, has a potential much more positive than the metal in the active state.

pass pipe
 * An iron pipe connecting the water at the back of one set of tubbing with that of another, or a pipe only in communication with one tub and open to the interior of a shaft.

paste
 * a. The claylike matrix of a dirty sandstone; e.g., the microcrystalline matrix of a graywacke, consisting of quartz, feldspar, clay minerals, chlorite, sericite, and biotite.

b. The mineral substance in which other minerals are embedded; groundmass (as of a porphyry). c. An imitation gemstone made from a certain type of lead glass; loosely applied to all glass imitation gemstones. d. A white clay body. e. In magnetic particle suspension, finely divided ferromagnetic particles in paste form used in the wet method. f. A slurry of sulfur and water, usually containing 30% to 50% of finely divided elemental sulfur. g. Material of which a porcelain body is formed. Hard paste (pite dure), composed of china stone and china clay, is true porcelain. Soft paste (pite tendre), composed of glass or frit with white, is artificial porcelain. h. Comparatively concentrated dispersion (greater than 10% by volume) of fine-solid or semisolid particles in a liquid; often shows elastic or plastic behavior.

paste fill
 * a. A class of backfills that has low water content; high densities (> or =75% by lot); and consistency, transport, and deposition properties different from those of traditional low-concentration slurries or other types of high-concentration backfill.

b. Paste fill (high pulp density) that does not settle out of suspension at zero flow density and does not produce free water when placed in a stope. Uncemented paste fill can generally be mobilized reasonably easily by pumping if left standing in a pipe for many hours.

paste pumping
 * The transport and placement of high-concentration, low-slump material by positive displacement through pipelines by pumps, similar to those used for concrete pumping. See also: paste fill.

pasting
 * The operation of mudcapping or plaster shooting whereby rock is blasted without drilling. An explosive is placed on top of the rock and covered by a cap of mud or similar material.

patch
 * a. A mine village, usually built and owned by a coal company.

b. A small placer property.

patchy
 * Distributed in an irregular manner, as when ore occurs in bunches or sporadically.

pat coal
 * Scot. The bottom, or lowest, coal sunk through in a shaft.

patent
 * A document that conveys title to the ground, and no further assessment work need be done; however, taxes must be paid. The procedure of obtaining a patent is divided into five steps: (1) a mineral surveyor is paid to make a patent survey, to adjust boundaries and correct errors, in which case an amended location should be made; (2) at least $500 worth of improvement must have been made per claim; (3) the presence of valuable mineral must be proven beyond reasonable doubt; (4) the matter is taken up with the local land office, and the proper notices must be published in the papers for a specified time; and (5) the purchase price of the land is paid and the patent is received.

patent ax
 * A type of surfacing machine employed to remove irregularities from the surface of blocks of stone.

patented claim
 * A claim to which a patent has been secured from the U.S. Government, in compliance with the laws relating to such claims. See also: patent.

patented rope
 * Galvanized steel rope.

patent survey
 * An accurate survey of a mineral claim by a U.S. deputy surveyor as required by law to secure a patent (title) to the claim.

Patera process
 * A metallurgical process consisting of a chloridizing roasting, leaching with water to remove base metals (some silver is dissolved and must be recovered), leaching with sodium hyposulfite for silver, and the precipitation of silver by sodium sulfide. The process was first carried out by von Patera at Joachimstal (Jachymov), Czech Republic.

paternoster pump
 * A chain pump; named from fancied resemblance of the disks and endless chain to a rosary.

pathfinder
 * In geochemical exploration, a relatively mobile element or gas that occurs in close association with an element or commodity being sought, but can be more easily found because it forms a broader halo or can be detected more readily by analytical methods. A pathfinder serves to lead investigators to a deposit of a desired substance. Often called indicator element, but this latter term is restricted by some authors to elements that are important components of the ores being sought.

path of percolation
 * See: line of creep.

patina
 * Strictly, the green film formed on copper and bronze after long exposure to the atmosphere. By extension, the term is applied to a film of any sort formed on wood, marble, chert, or other material after weathering or long exposure. See also: desert varnish.

patinated chert
 * Chert nodules with weathered or case-hardened surface layers.

patio
 * a. Mex. Cloth used by miners.

b. Sp. Place where minerals are concentrated. The patio floor is one on which silver and/or gold ore is amalgamated. See also: patio process; arrastre.

patio process
 * The patio process, dating back to the 16th century, was a crude chemical method for the recovery of silver by amalgamation in low heaps with the aid of salt and copper sulfate (magistral). See also: patio.

patronite
 * A monoclinic mineral, VS (sub 4) (?) ; synthetic VS (sub 4) is soft, gray-black, fine-grained; impure material constitutes an important ore mineral in the vanadium deposit at Minasragra, Peru.

pattern
 * a. As applied to diamond bits, the design formed by spacing and distributing the diamonds in conformance with a predetermined geometric arrangement on the crown of a bit. See also: concentric pattern; eccentric pattern.

b. The system followed in spacing boreholes. See also: checkerboarded; pattern shooting.

pattern molder
 * One who makes sand molds for castings; a molder.

pattern shooting
 * In seismic prospecting, the use of a number of energy sources arranged in a definite geometric pattern.

Patterson agitator
 * An agitator of the Pachuca-tank type in which air is replaced by a solution or water, under pressure from a centrifugal pump. See also: Pachuca tank.

Pattinson process
 * A process for separating silver from lead in which the molten lead is slowly cooled, so that crystals poorer in silver solifidy out and are removed, leaving the melt richer in silver.

Pattinson's pots
 * A series of pots for separating silver and lead by making use of the fact that the melting point of their alloys rises as the percentage of silver increases.

Paulin altimeter
 * This instrument measures barometric pressure and is quite accurate for a portable instrument. It can be used for finding the difference in pressure between points at various elevations without checking the setting of the pointer, or it can be checked against a mercury barometer and then used as a portable barometer. It is useful in making a survey of the drop in ventilation pressure throughout a mine.

paulingite
 * An isometric mineral, (K (sub 2) ,Ca,Na (sub 2) ,Ba) (sub 5) [Al (sub 10) Si (sub 32) O (sub 84) ].34-44H (sub 2) O ; zeolite group; forms rhombic dodecahedra; at the Columbia River Rock Island Dam, Wenatchee, WA.

Pauling's rules
 * Generalizations about coordination polyhedra and the ways they fit together in stable ionic crystal structures: (1) A coordination polyhedron of anions forms about each cation. (2) Electronic neutrality is maintained over short atomic distances. (3) Coordination polyhedra tend not to share edges or faces. (4) Highly charged cations minimize sharing of polyhedral elements.

pavement
 * a. A layer immediately underlying coal or any other workable material.

b. The floor of a mine. c. Any construction superimposed on a subgrade to reduce loading stresses and to protect it against the abrasive effects of traffic and weather. d. See: base rock. e. A bare rock surface that suggests a paved road in smoothness, hardness, horizontally, surface extent, or close packing of its units; e.g., boulder pavement, glacial pavement, desert pavement, limestone pavement, erosion pavement.

pavilion
 * Any of the undersides and corners of a brilliant-cut gem; they lie between the girdle and the collet.

paving breaker
 * An air hammer that does not rotate its steel.

paving sand
 * A type of commercial sand with applications divided into three general classes: concrete pavements, asphaltic pavements, and grouting.

pavonite
 * A monoclinic mineral, (Ag,Cu)(Bi,Pb) (sub 3) S (sub 5) ; at the Porvenir Mine, Bolivia. The synthetic phase, AgBi (sub 3) S (sub 5), has the same X-ray pattern.

pawl
 * A tooth or set of teeth designed to lock against a ratchet.

pay
 * A monoclinic mineral, CuAs (sub 2) ; pseudo-orthorhombic; forms intergrowths with novakite, koutekite, and arsenic; in Bohemia, Czech Republic. _E �b[ �d[ j4>��       � � DICTIONARY TERMS:pay a. That portion of a formation, deposit, prospe

a. That portion of a formation, deposit, prospect, or mine in which valuable mineral, oil, or gas is found in commercial quantity. b. Profitable ore. See also: pay dirt.

pay dirt
 * a. Gravel. Of alluvial deposits, sand rich enough to be excavated and treated to recover its valuable contents. See also: pay streak.

b. S. Afr. The same as payable ore, but in an alluvial deposit. Also called pay rock. See also: pay ore. c. Earth, rock, etc., that yields a profit to a miner.

pay formation
 * A layer or deposit of soil or rock whose value is sufficient to justify excavation.

pay gravel
 * a. Gravel containing sufficient heavy mineral to make it profitable to work.

b. In placer mining, a rich strip or lead of auriferous gravel. See also: pay ore.

pay limit
 * S. Afr. Grade below which the mining of ore is considered to become unpayable. There has been much discussion about mining below the pay limit for technical reasons, as a result of taxation, or to conserve natural resources.

pay load
 * a. In any winding or haulage system, the pay load is the weight of coal, ore, or mineral handled as distinct from dirt, stone, or gangue.

b. The mineral raised up the shaft from an underground mine.

pay material
 * The mineral to be recovered.

pay ore
 * Rock that, at current cost of discovery, development, and exploitation, can be mined, concentrated and/or smelted profitably at the ruling market value of products. Ore below this value or cut (the threshhold value) is unpay. Syn: pay rock. CF: pay streak. See also: pay dirt; pay gravel.

pay out
 * To slacken or to let out rope.

pay rock
 * See: pay ore.

pay shoot
 * A portion of a deposit composed of pay ore; generally a dipping band within a more continuous vein. See also: pay streak.

pay streak
 * a. The area of economic concentration of gold in a placer deposit.

b. The part of a vein or area of a placer deposit that carries the profitable or pay ore. See also: pay dirt; pay shoot. CF: pay ore.

peachblossom ore
 * See: erythrite.