Appendix:Dictionary of Mining, Mineral, and Related Terms/C/7

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cooler arch

An opening of truncated-cone shape in the tuyere breast of furnace. The tuyere cooler is placed in it.


Coolers in which atmospheric air is blown by a fan, through a nest of pipes, into a tower or chamber in which it comes into intimate contact with fine particles of water from atomizing nozzles. By the evaporation of some of this water the air rapidly becomes saturated at the wet-bulb temperature, the remaining water running off at the same temperature. This water is collected and pumped back through the nest of pipes, thereby cooling the air before it enters the spray chamber. The entering air then has a lower dry-bulb temperature than the atmosphere and, since its moisture content is unaltered, the wet-bulb is lower also.

cooling agent

A chemical added to an explosive during manufacture to suppress or inhibit the flame produced in blasting.

cooling floor

A floor upon which hot ore is placed for the purpose of cooling.

cooling load

The total amount of sensible and latent heat to be removed from a space to maintain desired conditions. For mines in operation, it is possible to measure the actual amount of heat generated in underground openings by observing temperature changes in a known weight flow rate of mine air. For projected mines and extensions of operating mines, the amount of heat produced must be calculated, knowing which of the sources of underground heat is operative.

cooling power

The rate at which air will remove heat from a body and may be measured dry or wet. The cooling power of air, as determined by the kata thermometer, is one of the basic environmental standards.

coontail ore

Banded ore consisting mainly of fluorite and sphalerite in alternate light- and dark-colored layers; occurs in the Cave-in-Rock district of southern Illinois.


A tetragonal mineral, (Pt,Pd,Ni)S ; sp gr, 9; (super ) in ultramafic rocks, such as the Bushveld, Transvaal, South Africa; an ore of platinum and palladium.

Cooper's lines

An anastomosing meshwork of minute curved and branching lines produced in rock by shearing under pressure.


Any one of a set of numbers designating linear and/or angular quantities that specify the position of a point on a line, in space, or on a given plane or other surface in relation to a given reference system; e.g., latitude and longitude are coordinates of a point on the Earth's surface. The term is usually used in the plural, esp. to designate the particular kind of reference system (such as spherical coordinates, plane coordinates, and polar coordinates).

coordinate system

Crystallographers customarily use a right-handed system with the z axis oriented positive upward, the y axis positive to the right, and the x axis positive toward the viewer. CF: axis; crystallographic axes.


a. Elastic, bituminous substances derived from algae.

b. A boghead coal in the peat stage. See also: elaterite.


Lean; said of ores.


An inclusive term for a wide variety of hard, brittle, semitransparent, yellowish to red fossil resins from various tropical trees (e.g., Copiafera and Agathis), being nearly insoluble in the ordinary solvents and resembling amber in appearance; e.g., Congo copal and kauri. Copal also occurs as modern resinous exudations. Syn: gum copal. See also: amber.


See: copalite.


An oxygenated hydrocarbon resembling copal from the blue clay of Highgate, near London, England. Syn: copaline; fossil copal.

Copaux-Kawecki fluoride process

A process for converting beryl to beryllium oxide by sintering a mixture of beryl, soda ash, sodium silicofluoride, and sodium ferric fluoride, leaching with hot water, and adding caustic soda to precipitate beryllium hydroxide, which is calcined to beryllia.


a. Derb. To contract to mine lead ore by the dish, load, or other measure.

b. An exchange of working places between miners. Also spelled coup. c. Derb. A duty or royalty paid to the lord or owner of a mine. d. Eng. A superficial deposit covering or coating the substrata. A cold, stiff, and wet clay. e. The upper or topmost section of a flask, mold, or pattern.


An alloy containing 55% copper and 45% nickel; used for thermocouples.


Derb. One who contracts to mine lead ore at a fixed rate; a miner.


A name for gypsum, generally in weathered state.


a. A triclinic mineral, Fe (super 2+) Fe (super 3+) (sub 4) (SO (sub 4) ) (sub 6) (OH) (sub 2) .20H (sub 2) O ; Syn: ferrocopiapite; yellow copperas; ihleite; knoxvillite.

b. The mineral group aluminocopiapite, calciocopiapite, copiapite, cuprocopiapite, ferricopiapite, magnesiocopiapite, and zincocopiapite. Syn: ihleite.


a. Cutting and trimming marble or other stone by use of a grinding wheel.

b. The top or cover of a wall usually made sloping to shed water. c. In quarrying, the process of cutting one slab into two without regard to the finish of the edges. d. The material or units used to form a cap or finish on top of a wall, pier, or pilaster to protect the masonry below from the penetration of water from above. e. Shaping stone or other hard nonmetallic material by use of a grinding wheel.

coping machine

A machine consisting of a gearing and a carborundum wheel for cutting and trimming marble slabs.


The process of moving the head of a theodolite laterally until its vertical axis lies in the produced vertical plane common to two plumblines. Syn: alignment. See also: jiggling in.


See: cupel.


a. A reddish metallic element that takes on a bright metallic luster and is malleable, ductile, and a good conductor of heat and electricity. Symbol, Cu. Occasionally occurs native, and is found in many minerals such as cuprite, malachite, azurite, chalcopyrite, and bornite. Its alloys, brass and bronze, are very important; U.S. coins are now copper alloys. Its oxides and sulfates are used as an agricultural poison and as an algicide in water purification.

b. An isometric native metal Cu ; metallic, red, soft, ductile and malleable; sp gr, 8.9; in oxidized zones of copper deposits, formerly a major source of native copper; the only native metal to occur abundantly in large masses; commonly occurs in dendritic clusters or mossy aggregates, sheets, or in plates filling narrow cracks or fissures. See also: native copper.


See: melanterite; copiapite; goslarite; coquimbite.


A sulfate of iron and copper resulting from the decomposition of copper pyrites.

copperas stone

Syn. for pyrite, from which copperas is often made.

copper barilla

Bol. Native copper in granular form mixed with sand. See also: coro-coro; barilla.

copper bottoms

A metallic product of very indefinite composition, made (usually) in reverberatory furnaces by smelting rich cupriferous substances without sufficient sulfur to quite satisfy the copper present.

copper chalcanthite

See: chalcanthite.

copper compress operator

A laborer who compresses copper scrap into bales for use in charging refining furnaces, by operating a hydraulic ram.

copper direct-firing process

A metallurgical process for recovering copper from low-grade complex ores in which a mixture of the ore and a small quantity of salt and coke are heated, and the oxides or sulfides reduce to metal that migrates or segregates in the form of thin films or flakes. These are later recovered by conventional flotation procedures.

copper flower

Any one of several indicator plants that serve as guides when prospecting for copper ores.

copper glance

See: chalcocite.


Copper-colored spots--generally in a first coat on iron and not easily covered with a second coat. Copperheads are spots of excessive oxidation with red iron oxide producing the color.

copper ingots

Notched bars of commercial copper used for casting purposes. The notches are provided for convenience in breaking the bars.


Impregnation with copper, or with some compound containing copper.

copper mica

A miners' name for chalcophyllite.

copper nickel

See: niccolite; nickeline.

copper-ore germ

A mixture of various copper minerals, such as green malachite, green or blue chrysocolla, blue azurite, and red cuprite.

copper pitch

A jet black to brownish pitchlike material carrying from 12.12% to 84.22% CuO and found in the oxidized zone. It has a conchoidal fracture, and where it occurs in large enough pieces may resemble obsidian or anthracite coal. It apparently may be a mixture of the hydrous oxides of copper and iron, oxide and carbonate of copper, oxide and silicate of copper, or more or less hydrated oxides of copper and manganese. All the varieties may have more or less chalcedony mixed with them.

copper precipitate

Impure copper that has been precipitated from copper-bearing solutions; it may contain iron and arsenic; cement copper.

copper-precipitation drum operator

In ore dressing, smelting, and refining, one who precipitates copper from mine water by tumbling mine water and shredded steel cans in a revolving drum.

copper pyrite

See: chalcopyrite.

copper rain

Minute globules thrown up from the surface of molten copper, when it contains but little suboxide.

copper segregation process

The process involves heating oxidized copper ore with a reducing agent and a halide salt at about 700 degrees C to produce metallic copper, which may then be recovered by ammonia leaching or by flotation with conventional copper sulfide collectors.

copper slate

Slate impregnated with copper minerals.

copper smoke

The gases from the calcination of copper sulfide ore. The gases contain sulfur dioxide, SO (sub 2) .

copper suboxide

See: cuprite.

copper sulfate

See: chalcanthite; copper sulfate pentahydrate.

copper sulfate pentahydrate

CuSO (sub 4) .5H (sub 2) O ; blue; triclinic; loses 5H (sub 2) O at 150 degrees C; white when dehydrated; slowly effloresces in air. Used in ore flotation and as a source of copper.

copper sulfide

a. A source of copper.

b. See: covellite; cupric sulfide; indigo copper. CF: digenite.

copper titanate

CuTiO (sub 3) . Sometimes added in quantities up to 2% to BaTiO (sub 3) to increase the fired density.

copper uranite

See: uranite; torbernite.

copper vitriol

See: chalcanthite.


a. A niobium-containing mineral used as raw material in the production of ferroniobium.

b. A variety of tetrahedrite.


The carrying down by a precipitate of substances that are normally soluble under the condition of precipitation.


One of two commodities that must be produced to make a mine economic; both influence output. A byproduct is produced in association with a main product or with coproducts. See also: byproduct.


Petrified excrement.


A trigonal mineral, Fe (sub 2) (SO (sub 4) ) (sub 3) .9H (sub 2) O ; dimorphous with paracoquimbite. Syn: white copperas.


A detrital limestone composed wholly or chiefly of mechanically sorted fossil debris that experienced abrasion and transport before reaching the depositional site and that is weakly to moderately cemented, but not completely indurated; esp. a porous light-colored limestone made up of loosely aggregated shells and shell fragments, such as the relatively recent deposits occurring in Florida and used for roadbeds and construction.

coquinoid limestone

A limestone consisting of coarse, unsorted, and often unbroken shelly materials that have accumulated in place without subsequent transportation or agitation, and generally having a fine-grained matrix. It is autochthonous, unlike the allochthonous coquina.


An alteration product of uraninite partly changed to gummite. Syn: uraninite.


A general name for any of a large group of bottom-dwelling, sessile, marine invertebrate organisms (polyps) that belong to the class Anthozoa (phylum Coelenterata), are common in warm intertropical modern seas and abundant in the fossil record in all periods later than the Cambrian, produce external skeletons of calcium carbonate, and exist as solitary individuals or grow in colonies.


Said of a firm carbonate rock formed by an intergrowth of frame-building corals and algae (esp. coralline algae). The material so formed is an excellent sediment binder in a coral reef.

coral limestone

A limestone consisting of the calcareous skeletons of corals, often containing fragments of other organisms and often cemented by calcium carbonate.


a. Pertaining to, composed of, or having the form of a coral, as coralline limestone.

b. Any organism that resembles a coral in forming a massive calcareous skeleton or base, such as certain algae or stromatoporoids.

coral mud and sand

Marine deposits formed around coral islands and coasts bordered by coral reefs, containing abundant fragments of corals. Near the reefs the particle sizes are relatively coarse and the deposit is described as coral sand; farther out, the particles become gradually smaller until the material is a coral mud.

coral ore

A curved, lamellar variety of liver-colored cinnabar from Idria, Austria.

coral rag

A well-cemented, rubbly limestone composed largely of broken and rolled fragments of coral-reef deposits; e.g., the Coral Rag of the Jurassic, used locally in Great Britain as a building stone.

coral reef

a. A coral-algal or coral-dominated organic reef; a mound or ridge of in-place coral colonies and accumulated skeletal fragments, carbonate sand, and limestone resulting from organic secretion of calcium carbonate that lithifies colonies and sands. A coral reef is built up around a potentially wave- and surf-resistant framework, esp. of coral colonies, but often including many algae; the framework may constitute less than half of the reef volume. Coral reefs occur today throughout the tropics, wherever the temperature is suitable (generally above about 18 degrees C, a winter minimum).

b. A popular term for an organic reef of any type.

coral sand

Sand-size particles formed from coral fragments. See also: coral mud and sand.

coral zone

The depth of the sea at which corals thrive.


A plant group, which is now extinct, that includes the Coniferales (pines and firs) and the Cycadales (cycads). The Cordaites were tall, slender trees that often attained heights of 100 ft (30.5 m). For a considerable height above the ground, the trunk was devoid of branches. The long, straplike leaves now form matted masses among the Coal Measure fossil plants.

cord-belt conveyor

A rubber belt consisting of spaced cotton duck cords embedded in the rubber and protected at the top by a breaker strip with thick rubber cover. The bottom of the belt contains one or two plies of heavy duct, to give transverse strength. See also: nylon belt.


An orthorhombic mineral, Mg (sub 2) Al (sub 4) Si (sub 5) O (sub 18) ; Mohs hardness, 7 to 7.5; an accessory in peraluminous granite, schist, and gneiss; a gem material called saphir d'eau, water sapphire, dichroite, and iolite. Syn: polychroite.

cordierite norite

Metamorphosed norite containing cordierite.


a. A comprehensive term for an extensive series or broad assemblage of more or less parallel ranges, systems, and chains of mountains, the component parts having various trends but the mass itself having one general direction; esp. the great mountain region of western North America from the eastern face of the Rocky Mountains to the Pacific Ocean, or the parallel chains of the Andes in South America; a mountain province.

b. An individual mountain chain with closely connected, distinct summits resembling the strands of a rope or the links of a chain; e.g., one of the parallel chains of the Rocky Mountains. c. A term also used in South America for an individual mountain range. Etymol: Spanish, chain or range of mountains, from Latin chorda, cord.

Cordirie process

The refining of lead by conducting steam through it, while molten, to oxidize certain metallic impurities.


An explosive compound consisting of cellulose nitrate and a restrainer, such as vaseline, used chiefly as a propellant.

cord of ore

About 7 tons, but measured by wagonloads, and not by weight. The expression "cord" is a term used in some parts of Colorado and applied only to low-grade ore; the smelting ore is reckoned by the ton.


A detonating fuse suitable for opencast and quarry mining. It consists of an explosive core of pentaerythritol tetranitrate (PETN) contained within plastic covering. It has an average velocity of detonation of 21,350 ft/s (6,500 m/s). This is practically instantaneous. Cordtex detonating fuse is initiated by electric or a No. 6 plain detonator attached to its side with an adhesive tape.

Cordtex relay

A new device to achieve short-interval delay firing with Cordtex. A relay is an aluminum tube with a delay device, and is inserted in a line of Cordtex where required. The relays are made with two delays, 15 ms and 20 ms, respectively.


A ribbed and napped textile material used for recovering coarse gold or other heavy metal or mineral from a stream of sand passing over it. A corduroy blanket is replaced about every 4 hours for washing to remove the gold.

corduroy spar

See: graphic granite.

corduroy texture

Bands of coarse-grained quartz and albite or microcline in rock.


A hexagonal mineral, Ba(Ce,La) (sub 2) (CO (sub 3) ) (sub 3) F (sub 2) ; rare; in pegmatites in nepheline syenites. 4� ��� ��� ?O� � � ��DICTIONARY TERMS:core a. A cylindrical section of rock, usually 5 to

a. A cylindrical section of rock, usually 5 to 10 cm in diameter and up to several meters in length, taken as a sample of the interval penetrated by a core bit and brought to the surface for geologic examination and/or laboratory analysis. To obtain a core in drilling. b. The central part of the Earth below a depth of about 1,800 mi (2,900 km), probably consisting of iron-nickel alloy. c. A hard, unburned central part of a piece of coal or limestone. CF: clinker. Also, an unburned or an overburned piece of limestone in hydrated lime. d. A cone or V-shaped mass of rock that is first blasted out in driving a tunnel. e. The central part of an anticlinal structure, or of a domal structure, or of mountains having a folded or a completely crumpled structure. f. See: drill core. CF: clinker; bit core.

core analysis

a. The characteristics of the minerals contained in a specific section of a core sample as determined petrographically, by metallurgical treatments and/or by chemical or cupelling methods. Also called core assay; core values.

b. As used by the petroleum industry, a study of a core sample to determine its water and oil content, porosity, permeability, etc.

Coreau detonnant

Detonating fuse used in blasting. Syn: Cordtex.

core barrel

a. A hollow cylinder attached to a specially designed bit and which is used to obtain and to preserve a continuous section, or core, of the rocks penetrated in drilling.

b. A tube inside a drill pipe and which is supported by a bit to receive the core, in core boring.

core bit

a. A hollow, cylindrical boring bit for cutting a core in rock drilling or in boring unconsolidated earth material. It is the cutting end of a core drill.

b. A hollow, cylindrical drill bit for cutting a core of rock in a drill hole; the cutting end of a core drill. Syn: coring bit.

core block

An obstruction inside a bit, reaming shell, or core barrel consisting of impacted core fragments or drill cuttings, which prevents entry of core into the core barrel. See also: block. Syn: core jam.

core boring

As used by soil- and foundation-testing engineers, a syn. for core; cuttings; drill sludge.

core box

a. The wooden, metal, or cardboard box divided into narrow parallel sections, used to store the cores at the surface as they are extracted from a core barrel or corer.

b. The box in which the core, or mass of sand producing any hollow part of a casting, is made.

core breaker

a. See: core lifter.

b. A sharp-cornered pluglike device inside an annular-shaped bit, which breaks up any core produced into pieces small enough to be washed out of the borehole as cuttings.

core catcher

a. Sievelike tray or device on or in which the core is ejected continuously from the upper end of a drill string, and is caught and held when core is recovered by counterflow or reverse-flow continuous core-drilling techniques.

b. See: core lifter. c. A steel spring fitted at the lower end of a soil sampler to keep the sample from dropping out. d. In deep boring, a ring of steel of wedge form cut into vertical stripes that encircles and rides on the core when drilling, but wedges the core in the core barrel when drilling ceases and the rods are lifted.

cored ammonium nitrate dynamite

The dynamites of this class come in cartridges 4 in (10.2 cm) and up in diameter and in weight strengths from 20% to 70%. Their water resistance is considered good (the gelatin core being responsible for this), but their fume characteristics are rated as poor. Besides providing increased water resistance, these explosives tend to exhibit the higher velocities characteristic of gelatin explosives (10,500 ft/s, 15,000 ft/s, and 17,000 ft/s) (3,200 m/s, 4,600 m/s, and 5,200 m/s), rather than the low and medium velocities characteristic of other straight ammonia dynamite. In addition, the gelatin core assures propagation of detonation through the entire explosives column. Gelatin cored ammonia dynamites also are very useful when an operator wishes to practice alternate velocity loading to attain a more effective one-two punch in conjunction with the use of short period or millisecond delay, electric blasting caps.

cored hole

a. A borehole put down by a core drill.

b. A cast hole cored with a dry-sand core instead of delivering as a hole directly from the pattern. In general, the term is applied to any hole in a casting that is not bored or drilled in the shop.

core dressing

A solution used to form clear skin at surface of core.

core drill

a. A rotary drilling rig that cuts and brings to the surface a core from the drill hole. It is equipped with a core bit and a core barrel.

b. A lightweight, usually mobile drill that uses tubing instead of drill pipe and that can core down from the grass roots. c. A mechanism designed to rotate and cause an annular-shaped rock-cutting bit to penetrate rock formations, produce cylindrical cores of the formations penetrated, and lift such cores to the surface, where they may be collected and examined. See also: calyx drill; diamond drill; rotary drill; shot drill. d. The act or process of producing a cylindrical core of rock, using a core-drilling machine and equipment. e. A lightweight, usually mobile drilling machine equipped with a hollow core bit and a core barrel that by rotation cuts out and recovers a rock core sample. f. A drill that removes a cylindrical core from the drill hole.

core drilling

a. The process of obtaining cylindrical rock samples by means of annular-shaped rock-cutting bits rotated by a borehole-drilling machine.

b. Drilling with a hollow bit and a core barrel to obtain a rock core.

core-drill sampling

The act or process of obtaining cylindrical samples of rock in the form of a core.

core dryer

A form in foundry work that serves to retain the shape of a core while it is being baked.

core extractor

a. A special tool that works like a screw or hydraulic jack, used to push core out of a core barrel. Also called core plunger; core pusher.

b. A fishing tool designed to recover core dropped from a core barrel and resting on the bottom of a borehole. Also called basket; core basket; core fisher; core grabber; core picker.

core grouting

Material used in and/or the act or process of injecting small fragments of rock or coarse sand into a core barrel to wedge the core inside the barrel when no core lifter is used, as when using straightwall bits or drilling with a shot drill.

core hole

A boring by a diamond drill or other machine that is made for the purpose of obtaining core samples.

core intersection

The point in a borehole where an ore vein or body is encountered, as shown by the core; also, the width or thickness of the orebody, as shown by the core. Also called core interval.

core interval

See: core intersection.

core jam

See: core block.

core library

A structure in which boxed cores from numerous recorded localities are stored and kept available for inspection and study.

core lifter

A spring clip at the base of the core barrel that grips the core, enabling it to be broken off and brought out of the hole. Also called core clip; core gripper; core spring; ring lifter; split-ring lifter. Syn: catcher; core breaker; core catcher; spring lifter; spring core lifter; lifter.

core load

The explosive core of detonating cord, expressed as the number of grains of explosive per foot or grams per meter.

core loss

The portion of rock cored but not recovered. CF: core recovery.

core of the Earth

a. The dense central part of the Earth, below a depth of about 1,800 mi (2,900 km). Syn: centrosphere.

b. The Earth is believed to consist of the following: inner core, solid, 860 mi (1,384 km) radius; outer core, liquid, 1,300 mi (2,092 km) thick; mantle, solid, 1,800 mi (2,897 km) thick; and crust, solid, 622 mi (1,001 km) thick.

core orientation

a. The act or process of using information obtained from magnetic polarity or other measurements of a piece of core in an attempt to determine the downhole bearing of the structural features of the rock formation as displayed in the core.

b. To place a piece of core in the same relative plane as it occupied below the surface. See also: true dip.

core plug

A cylinder containing chemically treated sand and used for stemming shotholes in coal mines.

core rack

a. A framework built to support several tiers of core boxes.

b. Grooved or partitioned tray, supported on legs or sawhorses, on which core is placed when removed from a core barrel for inspection or temporary storage before being placed in boxes.

core recovery

a. The proportion of the drilled rock column recovered as core in core drilling. The amount withdrawn generally is expressed as a percentage of the theoretical total in general terms, as excellent, good, fair, or poor. CF: core loss.

b. The amount of the drilled rock withdrawn as core in core drilling, generally expressed as a percentage of the total length of the interval cored.

core run

Technically, the distance cored per round trip, which is expressed in number of feet or in relative terms, as short or long. Core blocks may occur before the core barrel is filled; the barrel then is short of being full, resulting in a short core run. Loosely, the amount of core recovered per round trip.

core sample

One or several pieces of whole or split parts of core selected as a sample for analysis or assay.

core sand

Silica sand to which a binding material has been added to obtain good cohesion and porosity after drying for the purpose of making cores.

core saw

A machine capable of rotating at high speed, equipped with a thin metal disk having diamonds inset in its edge. Used somewhat like a bench saw to cut core longitudinally into sections. CF: core splitter; diamond-saw splitter.

core shack

A roofed and enclosed structure in which core-filled boxes are stored. Also called core house; core shanty.

core sludge

The slurry produced during abrasion by the cutting bit, or through fracture and grinding of part of the sample during this process.

core splitter

Tool employing a chisel to split core longitudinally in half, rarely in quarter, sections. One-half usually is assayed, and the other half is retained and stored. Term also may be applied to a diamond saw used for the same purpose. See also: core saw.

core test

A hole drilled with a core drill, usually for the purpose of securing geologic information and sometimes with the purpose of investigating geologic structure.

core texture

See: atoll texture.

core-type spiral chute

A spiral chute having a center core or column about which it is fabricated, with the core serving as the inside guard.

core values

Used in a general sense as a syn. for core analysis; core assay. In a strict sense, the term should not be used to designate the mineral content of the core sample unless the valuable mineral is gold, silver, platinum, etc.

core velocity

The zone of maximum air velocity in a mine roadway, usually at or near the center of the road.

core wall

In a battery wall, those courses of brick, none of which are directly exposed on either side.

core wash

a. The portion of the core lost through erosive action of the drill circulation fluid.

b. The act or process of erosion of core by washing action of the drill circulation fluid.


A variable composition between the center and surface of a unit of structure (such as a dendrite, grain, or carbide particle) resulting from nonequilibrium growth that occurs over a range of temperature.

coring bit

See: core bit.

coring tool

A tool that is used when a core is required. In drilling, where speed is the aim, cores are not made. When, however, an important bed or horizon is approached, and detailed geological information is required, the coring bit is inserted and core drilling commenced. Also called corer.

Corinthian process

See: Carinthian process.

cork fossil

A variety of amphibole or hornblende, resembling cork; the lightest of all minerals.


a. A device resembling a corkscrew, used as a fishing tool.

b. A borehole following a spiraled course. c. A cylindrical surface, such as the outer surface of a piece of spirally grooved core. Also called fluted core.

corkscrew core

See: fluted core.


See: taper bit.


A translucent red variety of chalcedony. Also spelled carnelian.

corneous manganese

a. See: photicite.

b. A carbonated variety of rhodonite.


a. A point on a tract of land at which two or more surveyed boundary lines meet; e.g., a township corner.

b. A term that is often incorrectly used to denote the physical station, or monument, erected to mark the corner.

corner-fastened tray conveyor

See: suspended tray conveyor.

corner-hung tray conveyor

See: suspended tray conveyor.

corner racking

Square or triangular strips of pinewood fixed vertically down each corner of a rectangular shaft to secure and stiffen the timber sets.


In Wales, bands of clay ironstone.


An orthorhombic mineral, Cu (sub 3) (PO (sub 4) )(OH) (sub 3) ; occurs in peacock-blue minute crystals and encrustations in Katanga, Zaire, and Bwana M'Kubwa, Zambia.

Corning table

See: Bilharz table.

Cornish diamond

Eng. A quartz crystal from Cornwall.

Cornish engine

See: Cornish pump.

Cornish mining ton

The weight equal to 21 hundredweight of 112 lb each, or 2,352 lb (1,066.87 kg).

Cornish pump

A single-acting engine in which the power for pumping operations was transmitted through the action of a cumbersome beam. Syn: Cornish engine.

Cornish rolls

A geared pair of horizontal cylinders, one fixed in a frame and the other held by strong springs. The distance apart is adjusted by distance pieces of shims. Used for grinding.

Cornish stone

A variety of china stone composed of feldspar, mica, and quartz and used as a bond in the manufacture of pottery. Syn: Cornwall stone. CF: china stone.


A hornfels formed by contact metamorphism, and consisting of micas, quartz, and feldspar. CF: leptynolite. Etymol: From the classic name for Cornwall, England.


A triclinic mineral, Cu (sub 5) (AsO (sub 4) ) (sub 2) (OH) (sub 4) ; dehydrated from cornwallite.


a. A yellow, gelatinous substance, apparently in albumen with 97% water; found in fissures in diatomite deposit of Luneburger Heide, Hanover, Germany. It may be an organic matter derived from the diatoms or a fungus.

b. A blue, green, hydrous copper silicate; glassy. The colloidal phase of chrysocolla.


A monoclinic mineral, Cu (sub 5) (AsO (sub 4) ) (sub 2) (OH) (sub 4) .H (sub 2) O ; emerald-green; dehydrates to cornubite.

Cornwall stone

See: Cornish stone.


A dressed product of copper works in South America, consisting of grains of native copper mixed with pyrite, chalcopyrite, mispickel, and earthy minerals. See also: copper barilla; barilla.

Coromant cut

A new drill hole pattern in which two overlapping holes of diameter about 2-1/4 in (5.7 cm) are drilled in the tunnel center and left uncharged. These holes form a slot roughly 4 in by 2 in (10.2 cm by 5.1 cm) to which the easers can break. All the holes in the round are parallel and in line with the tunnel. Short-delay detonators are used for the easer holes and 1/2-s delays for the rest of the round. A pull of 10 ft (3.0 m) per round has been obtained in strong rock with 10.5-ft (3.2-m) holes. Explosive consumption for the easer holes is about 0.2 lb/ft (0.3 kg/m) of hole.


a. A microscopic zone of minerals, usually arranged radially around another mineral. The term has been applied to reaction rims, corrosion rims, and originally crystallized minerals.

b. A Spanish term meaning crown. Sometimes used in the Southwestern United States as a syn. for diamond bit. c. Rim of alteration product surrounding an earlier formed crystal, commonly the result of reaction with a cooling magma. Syn: kelyphitic rim; kelyphite; reaction border; kelyphytic rim. See also: reaction rim.


A monoclinic mineral, Pb(Mn (super 4+) ,Mn (super 2+) ) (sub 8) O (sub 16); cryptomelane group; pseudotetragonal; at the Coronado vein, Clifton-Morenci district, AZ.


A rock containing mineral grains surrounded by coronas.


a. A process of erosion whereby rocks and soil are mechanically removed or worn away by the abrasive action of solid materials moved along by wind, waves, running water, glaciers, or gravity. Syn: abrasion; attrition.

b. A term formerly used as a syn. of corrosion, or as including the work of corrosion.

corrected effective temperature

The scales of effective temperature take into consideration the temperature, humidity, and speed of the air. The effects of radiant heat can be included in an assessment of effective temperature by using the globe thermometer temperature instead of the dry-bulb temperature in those cases when the reading of the globe thermometer is higher than the dry-bulb temperature. In such cases, the result is described as the corrected effective temperature.

correcting wedge

A deflection wedge used to deflect a crooked borehole back into its intended course. See also: deflecting wedge.

correction chart

A chart, graph, or table giving the true angle of the inclination of a borehole for specific apparent angles as read from the etch line in a specific-size acid bottle. See also: capillarity-correction chart.

correction factor

See: assay plan factor.

correction line

See: standard parallel.

correctly placed material

a. Material correctly included in the products of a sizing or density separation.

b. In cleaning, the material of specific gravity lower than the separation density that has been included in the low-density product, or material of specific gravity higher than the separation density that has been included in the high-density product.


a. To show correspondence in character and stratigraphic position between such geologic phenomena as formations or fossil faunas of two or more separated areas. Adj. belonging to the same stratigraphic position or level.

b. To establish a definite stratigraphic relationship between strata that are separated by distance or by geologic disturbance; e.g., to find which coalbeds in one coalfield or part thereof correspond with (or are the same as) those of another coalfield. c. To plot or to arrange two surveys, the surveys of two mines, or the underground and the surface, on the same base line or to a common meridian.


a. The determination of the equivalence in geologic age and/or stratigraphic position of two formations or other stratigraphic units in separated areas; or, more broadly, the determination of the contemporaneity of events in the geologic histories of two areas. Fossils constitute the chief evidence in problems of such correlation. See also: lithologic correlation.

b. The identification of a phase of a seismic record as representing the same phase on another record, thus relating reflections from the same stratigraphic sequence or refractions from the same marker.

correlation shooting

A seismic shooting method in which isolated profiles are shot and correlated to obtain relative structural positions of the horizons mapped. CF: continuous profiling.


A clay mineral having 1:1 regular interstratification of trioctahedral chlorite with either trioctahedral vermiculite or trioctahedral smectite.

corridor system

See: methane drainage.


a. To eat away by degrees as if by gnawing.

b. To wear away or to diminish by gradually separating or destroying small particles or converting into an easily disintegrated substance; esp., to eat away or to diminish by acid or alkali reaction or by chemical alteration.

corroded crystal

A phenocryst that after crystallization is more or less reabsorbed or attacked by the magma, or a crystal in a vein or a pegmatite that is partly dissolved by later solutions. The process is probably much the same in all three instances.

corroding lead

Lead of purity exceeding 99.94% , suitable for the production of white lead.


a. A process of erosion whereby rocks and soil are removed or worn away by natural chemical processes, esp. by the solvent action of running water, but also by other reactions such as hydrolysis, hydration, carbonation, and oxidation. Syn: chemical erosion.

b. A term formerly used interchangeably with corrasion for the erosion of land or rock, including both mechanical and chemical processes. The mechanical part is now properly restricted to corrasion and the chemical to corrosion. Verb: corrode. c. See: magmatic corrosion; abrasion. See also: attrition.

corrosion border

One of a series of borders of one or more secondary minerals around an original crystal, representing the modification of a phenocryst due to the corrosive action of its magma. CF: reaction rim. Syn: corrosion zone; resorption border.

corrosion potential

The steady-state irreversible potential of a metal or alloy in a constant corrosive environment.

corrosion rate

The rate that a metal or alloy is removed because of corrosion. This may be expressed in terms of loss in weight or loss of thickness in a given period of time. (Corrosion rates in terms of thickness change refer to the loss of metal from one side only.)

corrosion surface

A pitted, irregular bedding surface found only in certain carbonate sediments, characterized by a black manganiferous stain, and presumed to result from cessation of lime deposition and from submarine solution or resorption of some of the previously deposited materials. Syn: corrosion zone.

corrosion zone

See: corrosion surface; corrosion border.


Where on a small scale, beds are much wrinkled, folded, or crumpled, they are said to be corrugated. On a larger scale, they are said to be contorted.

corrugated friction socket

A fishing tool.

corrugated trough

A trough with corrugations formed into the bottom to assist coal travel on steep grades or under wet conditions.


In coal, that part of the axis of a vascular plant that surrounds the central cylinder and is separated from the cylinder by the endodermis, and limited on the outside by the epidermis.


A rock consisting of corundum and iron oxides. See also: emery rock.


An iron-bearing variety of clinchlore.


A trigonal mineral, Al (sub 2) O (sub 3) ; hematite group; forms hexagonal prisms with basal and rhombohedral parting; red (ruby), blue (sapphire), green (oriental emerald), reddish-brown, white, or gray; defines 9 on the Mohs hardness scale; in nepheline syenite pegmatites and placer deposits. Emery is granular corundum mixed with magnetite and spinel. Synthetic corundum made from bauxite together with other manufactured abrasives have largely replaced natural materials.

corundum cat's eye

Corundum showing a bluish, reddish, or yellowish reflection of light, or lighter shade, than the stone itself. CF: asterism; star ruby; star sapphire.


A monoclinic mineral, (Na,K,Ca,Mg) (sub 2) (V (super 5+) ,V (super 4+) ) (sub 8) O (sub 26) .6-10H (sub 2) O ; weakly radioactive; associated with carnotite in Colorado and Utah; a source of vanadium. Syn: blue-black ore.


An orthorhombic mineral, Pb (sub 2) Bi (sub 2) S (sub 5) ; a source of bismuth.


Contemporaneous deposition.


The study of the origin, distribution, and abundance of elements in the universe.


a. A trench cut across the conjectured line of outcrop of a seam or orebody to expose the full width.

b. The channel eroded by a flow of water to expose mineral deposits during prospecting work. c. In prospecting, to dig shallow pits or trenches designed to expose bedrock. Etymol: Cornish.


a. The removal of soil and subsoil by a rushing of water, to expose rock formations in prospecting for reefs or lodes.

b. Proving an ore deposit or vein by trenching across its outcrop at approx. right angles. c. Tracing a lode by pits sunk through overburden to underlying rock.

costean pit

Corn. A pit sunk to bedrock in prospecting.

cotectic line

A special case of the boundary line, in ternary systems, along which one of the two crystalline phases present reacts with the liquid, upon decreasing the temperature, to form the other crystalline phase. Syn: reaction curve; reaction line.

cotectic surface

A curved surface in a quaternary system, representing the intersection of two primary phase volumes, one or both of which are solid solution series. It is the bivariant equivalent of the univariant cotectic line in ternary systems.


Eng. To mat together; to entangle. Frequently applied to a hard, crossgrained, tough stone or coal, as cottered coal.


A variety of quartz having a peculiar metallic pearly luster.

cotton ball

See: ulexite.

cotton chert

An obsolete syn. of chalky chert.

cotton rock

a. A term used in Missouri for a soft, fine-grained, siliceous, white to slightly gray or buff magnesian limestone having a chalky or porous appearance suggestive of cotton.

b. The white or light-colored decomposed exterior surrounding the dense black interior of a chert nodule.

cotton stone

A variety of mesolite. See also: mesolite; cotton rock.

Cottrell meter

This instrument applies the veiling brightness method of producing threshold conditions. When in use the sighting telescope is directed toward some critical detail of the visual task and the veiling brightness is adjusted until it matches the background. The gradient filter is then turned until the target detail is at threshold visibility.

Cottrell operator

In ore dressing, smelting, and refining, one who recovers magnesium dust particles remaining in magnesium gas after processing, using a battery of Cottrell electrical precipitators. Also called agglomerator operator; dust operator.

Cottrell precipitator

An electrostatic device whereby negatively charged dust or fume particles are attracted to a positively charged wire electrode enclosed in a flue, the walls of which act as the other electrode. Widely used for treating sulfuric acid mist, cement mill dust, power-plant fly ash, metallurgical fumes, etc.


An orthorhombic mineral, PbCl (sub 2) ; soft; acicular crystals.


a. A term applied in the Western United States to a small stream, often intermittent. Also, the bed of such a stream when dry.

b. A term applied in the Northwestern United States to a dry or intermittent stream valley, gulch, or wash of considerable extent; esp. a long, steep-walled, trenchlike gorge or valley representing an abandoned overflow channel that temporarily carried meltwater from an ice sheet, e.g., the Grand Coulee (formerly occupied by the Columbia River) in Washington State. c. A small valley or a low-lying area. Etymol: French coulee, flow or rush of a torrent. Pron: koo-lee. Syn: coulie. d. A tonguelike mass of debris moved by solifluction (Monkhouse, 1965, p. 81). e. A flow of viscous lava that has a blocky, steep-fronted form. Also spelled: coulee.

coulee lake

A lake produced by the damming of a water course by lava.


See: coulee.

coulomb attraction

The attraction between ions of opposite electric charges.

coulomb damping

a. The dissipation of energy that occurs when a particle in a vibrating system is resisted by a force whose magnitude is a constant independent of displacement and velocity, and whose direction is opposite to the direction of the velocity of the particle. Also called dry friction damping.

b. See: specific damping capacity.


An isometric mineral, Fe (super 2+) V (super 3+) (sub 2) O (sub 4) ; spinel group; a source of vanadium; formerly called vanado-magnetite.

Coulter counter

A high-speed device for particle size analysis designed by W.H. Coulter and now made by Coulter Electronics, Inc., Chicago. A suspension of the particles flows through a small aperture having an immersed electrode on either side with particle concentration such that the particles traverse the aperture substantially one at a time. Each particle, as it passes, displaces electrolyte within the aperture, momentarily changing the resistance between the electrodes and producing a voltage pulse of magnitude proportional to practical volume. The resultant series of pulses is electronically amplified, scaled, and counted.


a. A gangway driven obliquely upwards on a coal seam from the main gangway until it cuts off the faces of the workings, and then continues parallel with the main gangway. The oblique portion is called run.

b. A crossvein. c. An instrument for the detection of uranium and thorium. d. A term used for any device that registers radioactive events, i.e., alpha counter, beta counter, Geiger-Mueller counter, scintillation counter. The term is correctly used only for devices that actually register number of events, but is often erroneously applied to count rate meters that register events per unit time. e. An apparatus for recording the number of strokes made by a pump, an engine, or other machinery.


Drilling or boring a flatbottomed hole, often concentric with other holes. Syn: counterflush boring; reversed flush boring.

counter chute

A chute through which the coal from counter-gangway workings is lowered to the gangway below.

counter coal

Coal worked from breasts or bords to the rise of a counter gangway.


Arrangement in which ore, or pulp, proceeds in one direction and is progressively stripped of part of its contained mineral, while the enriched fraction thus produced moves in the opposite direction, the results being central feed, with discharge of high-grade concentrate at one end of the process and low-grade or barren tailing at the other.

countercurrent braking

Braking accomplished by reversing the motor connections, at the same time inserting appropriate resistance in the rotor circuit to adjust the negative torque to the desired value. With this method, complete control of deceleration is obtained, even to a dead stop. Its greatest disadvantage is that it is expensive in current consumption. It is unsuitable for winders sited at depth, owing to the heat given out.

countercurrent decantation

The clarification of washery water and the concentration of tailings by the use of several thickeners in series. The water flows in the opposite direction from the solids. The final products are slurry that is removed as fluid mud and clear water that is reused in the circuit. May be broader than just thickener. Syn: cascade upgrading.

countercurrent principle

A means of maintaining the chemical potential at a uniform level during a reaction.


In a heat exchanger, where the fluid absorbing heat and the fluid losing heat are so directed that lower and higher temperature of the one is adjacent to the lower and higher temperature of the other, respectively. Ordinarily, the one fluid is flowing in the opposite direction from the other, hence the term.

counterflush boring

See: counterboring.

counter gangway

A gangway driven obliquely across the workings to a higher level, or a gangway driven between two lifts and sending its coal down to the gangway below through a chute.


Mid. An underground heading driven parallel to another, and used as the return air course.


See: cast.


In a twist drill, the tapered and relieved cutting portion situated between the pilot drill and the body.


A cross vein running at approx. right angles to the main orebody.


Slate, size 20 in by 10 in (50.8 cm by 25.4 cm); a duchess is 24 in by 12 in (61.0 cm by 30.5 cm), and a princess is 24 in by 14 in (61.0 cm by 35.6 cm). Terms descriptive of slate trimmed for roofing.

counting assay

Approximate method of analysis, where particles of value and gangue are similar in shape and size, and their proportions can be assessed by inspection, probably under a low-powered microscope.

country bank

Arkansas. A small mine supplying coal for local use only.

country rock

The rock enclosing or traversed by a mineral deposit. Originally a miners' term, it is somewhat less specific than host rock. Syn: wall rock.

County of Durham system

A combination of the panel and room-and-pillar method of mining. See also: room-and-pillar.

coupled wave

A type of surface wave that is continuously generated by another wave that has the same phase velocity. Syn: C-wave.


Genetically related paired sedimentary laminae, generally occurring in repeating series, as varves, but applied to laminated nonglacial shales, evaporites, and other sediments as well.


a. A device for connecting tubs or mine cars to form a set or journey. See also: automatic clip; clip; shackle.

b. A connector for drill rods, casing, or pipe with identical box or pin threads at either end.

coup plate

In coal mining, steel plate on which tubs are turned from one set of rails to another.


a. To conduct the ventilation backward and forward through the workings, by means of properly arranged stoppings and regulators.

b. A seam of coal. c. To ventilate a number of faces in series. d. An unproductive vein as opposed to a lode. e. The horizontal direction of a geologic structure. Syn: course of ore; strike.

coursed ventilation

Mine ventilation by the same air current, i.e., without splitting of air.

course of ore

a. A horizontal shoot. An older term.

b. See: chute; course.

course of vein

The strike of a vein; direction of the horizontal line on which it cuts the country rock.

course stacking

The method of shovel operation in which no ground is hauled away. The shovel simply stacks the ground on the opposite side from the working cut, or it may turn entirely around, dumping the spoil on a bank behind.


The control of ventilation in mines, as by doors, brattices, and stoppings.

coursing bubble

One rising freely through the cell during froth flotation.


A method used by companies for checking the amount of refuse in coal. The refuse is picked daily from a few cars of run-of-mine coal, and when the amount of refuse is considered unreasonable, it is shown to the miner and the laborers. They may be suspended from work if the amount and size of refuse is too high.

courthouse inspector

In bituminous coal mining, one who examines mine cars of coal for impurities, such as slate, rock, and dirt, by the courthouse system (selecting cars at random for examination). Rejects, on basis of inspection, any group or lot of cars containing too much impurity.


A form of asphaltum allied to gilsonite.

cousin Jack

Cornish miner, usually far from home, important to U.S. mining.


A statistical measure of the correlation between two variables. In geostatistics, covariance is usually treated as the simple inverse of the variogram, computed as the overall sample variance minus the variogram value. These covariance values, rather than variogram values, are actually used in kriging matrix equations for greater computational efficiency.


See: covellite.


A hexagonal mineral, CuS ; metallic indigo blue with iridescent tarnish; soft; a supergene mineral in copper deposits; a source of copper. Syn: blue copper; covelline; indigo copper. See also: copper sulfide.


a. The sedimentary accumulation over the crystalline basement. See also: cover mass.

b. The vertical distance between any position in strata and the surface or any other position used as a reference. See: surface. c. The pattern or number of drill holes (pilot holes) deemed adequate to detect water-bearing fissures or structures in advance of mine workings. Syn: pilot-hole cover. d. Total thickness of material overlying mine workings or an orebody. See also: burden; mantle; cover rock. CF: rock cover.

cover brick

Common term for arch brick used to line soaking-pit covers.

cover gap

The area in advance of mine workings not adequately probed by pilot holes to detect the presence of water-bearing fissures or structures.

cover hole

One of a group of boreholes drilled in advance of mine workings to probe for and detect water-bearing fissures or structures.

cover line

The point at which the overburden meets the coal.

cover load

The load due to the weight of the superincumbent rock.

cover mass

The material overlying the plane of an angular unconformity. See also: cover.

cover rock

See: cover.

cover stress

The stress induced by the cover load only and which is uninfluenced by the proximity of any excavations.

cover work

Lumps of copper too large to pass the screen, which accumulate in the bottom of the mortar of the stamp.


York. The finest crushed lead ore. Also called coe.

Cowper-Siemens stove

A hot-blast stove of firebrick on the regenerative principle.


Gray marl. Syn: cushat marl.

cow sucker

A cylindrical heavy piece of iron attached to a cable or wire line, making it descend rapidly into a borehole when the cable or line is not attached to a string of drilling tools or equipment. Also called bug; bullet; go-devil.

coyote hole

A small tunnel driven horizontally into the rock at right angles to the face of the quarry. It has two or more crosscuts driven from it parallel to the face. It is in the ends of these crosscuts that the explosive charge is generally placed, and the remaining space in the tunnel is filled up with rock, sand, timbers, or concrete, to act as stemming or tamping. Same as gopher hole.

coyote-hole blasting

See: coyote shooting.

coyote shooting

A method of blasting using a number of relatively large concentrated charges of explosives placed in one or more small tunnels driven in a rock formation. Syn: coyote-hole blasting.

C.P. Hemborn dust extractor

A dust trap in which the clean air flows inwards around the outside of the drill rods, and the dust and chippings are extracted in the airstream passing through the hollow rods. It includes a drum-type dust container with filter units. The appliance requires special rods and bits. See also: dust trap.


Abbrev. for clinopyroxenes. CF: opx.

crab locomotive

A trolley locomotive fitted with a crab or winch for hauling mine cars from workings where a trolley wire is not installed.

crab operator

In bituminous coal mining, one who maintains and operates a crab (electric motor equipped with a drum and haulage cable mounted on a small truck) to pull loaded mine cars from working places to haulageways in the mine.

crab winch

An iron machine consisting of two triangular uprights between which are two axles, one above the other. These machines are frequently used in connection with pumping gear where mine shafts are not deep. Also called crab.

crackle breccia

An incipient breccia having fragments parted by planes of rupture but showing little or no displacement. It is commonly a chemical deposit.

crackled texture

A concentric texture of ore minerals in which minute cracks have developed by shrinkage during crystallization of the original colloid.

cracks of gas

Puffs or explosions of gas in blast furnaces.

crack wax

A dark-colored variety of ozokerite showing a granular fracture.


a. A wooden box, longer than wide provided with a movable slide and hopper and mounted on two rockers, for washing gold-bearing earths. Also known as rocker cradle.

b. The part of a car dumper in which the car rests when it is dumped. c. The balance platform for the cage at the bottom of some shafts. d. Device by means of which a small diamond or percussive-type drill may be attached to a drill column or arm. Also called saddle. e. The trough-shaped metal support for a mounted pneumatic drill. f. To wash, as gold-bearing gravel in a mining-cradle. g. Mounting for a rock drill.

cradle dump

A tipple that dumps cars with a rocking motion.

Craelius drilling machine

A small, fairly light boring machine for shallow exploratory borings underground. It drills in any direction (downwards, upwards, horizontally, or obliquely) to depths of from 200 to 1,000 m, but usually only 50 m. It uses coring or solid bits, with or without flushing and can be driven either by hand, any oil engine, compressed air, or electricity.


a. A steep precipitous point or eminence of rock, esp. one projecting from the side of a mountain. Syn: craig.

b. An obsolete term for a sharp, rough, detached, or projecting fragment of rock.


See: crag.


a. A contrivance for holding parts of a frame in place during construction. It usually consists of a steel bar along which slide two brackets between which the work is fixed, one of the brackets being pegged into a hole in the bar while the other is adjustable for position by means of a screw.

b. A locking bar of incorrodible metal used to bind together adjacent stones in a course, and having bent ends, one of which is fastened into each stone. Also called a cramp iron.


An appliance for holding stones or other heavy objects that are to be hoisted by crane. It consists of a pair of bars hinged together like scissors, the points of which are bent inwards for gripping the load, while the handles are connected by short lengths of chain to a common hoist ring.


a. A stonecutters' hammer for dressing ashlar. Its head is made up of pointed steel bars of square section wedged in a slot in the end of the iron handle.

b. To dress stone with a crandall.


a. A trigonal mineral, CaAl (sub 3) (PO (sub 4) ) (sub 2) (OH) (sub 5) .H (sub 2) O ; forms compact to cleavable or fibrous masses; formerly called kalkwavellite.

b. The crandallite mineral group of trigonal phosphates and arsenates: arsenocrandallite, arsenoflorencite-(Ce), arsenogorceixite, arsenogoyazite, crandallite, dussertite, eylettersite, florencite-(Ce), florencite-(La), florencite-(Nd), gorceixite, goyazite, lusungite, philipsbornite, plumbogummite, waylandite, and zairite.

crane boom

A long, light boom, usually of lattice construction.

crane ladle

A pot or ladle supported by a chain from a crane; used for pouring molten metals into molds.

crane rope

Wire rope consisting of 6 strands of 37 wires around a hemp center.

crate dam

A dam built of crates filled with stone.


a. A typically bowl-shaped or saucer-shaped pit or depression, generally of considerable size and with steep inner slopes, formed on a surface or in the ground by the explosive release of chemical or kinetic energy; e.g., an impact crater or an explosion crater.

b. A basinlike, rimmed structure that is usually at the summit of a volcanic cone. It may be formed by collapse, by an explosive eruption, or by the gradual accumulation of pyroclastic material into a surrounding rim. CF: caldera. c. The formation of a large funnel-shaped cavity at the top of a well, resulting from a blowout or occasionally from caving. d. In blasting, the funnel of rupture, which in bad rock may have very steep sides and a relatively small volume of broken rock. Syn: lunar crater.

crater cuts

These cuts consist of one or several fully charged holes in which blasting is carried out towards the face of the tunnel, i.e., toward a free surface at right angles to the holes. These represent in principle a completely new type of cut and make use of the crater effect that is obtained in blasting a single hole at a free rock surface. The possibility of a uniform enlargement can be counted on. This means that if the scale is enlarged so that the diameter and depth of hole and length of the charge are all doubled, e.g., a crater of double the depth will be obtained. The number of holes can be increased instead of increasing the diameter of the holes.

crater theory

Crater theory defines an optimum burden or distance to a free face at which a spherical explosive charge is buried and produces the greatest volume of broken and excavatable rock. This distance is unique based on rock type and explosive type. The theory also defines the critical depth or spherical charge buried depth at which surface disturbance is barely detectable, resulting in slight surface mounding and minor cracking.


See: shield.


Of or pertaining to a craton.


A part of the Earth's crust that has attained stability, and has been little deformed for a prolonged period. The term is now restricted to the extensive central areas of the continents.


A piece of a vein left uncut as a support.


One of a pair of an endless chain of plates driven by sprockets and used instead of wheels, by certain power shovels, tractors, bulldozers, drilling machines, etc., as a means of propulsion. Also any machine mounted on such tracks.

crawler track

An endless chain of plates used instead of wheels by certain power shovels, continuous miners, etc.


A low passageway that only permits the passage of a person by crawling. Syn: cat run.


A rusty impure meerschaum.


Sometimes designates a very high-quality drill diamond.


A monoclinic mineral, CuMnO (sub 2) .


A monoclinic mineral, Ca (sub 3) Al (sub 2) (SO (sub 4) )(F,OH) (sub 10) .2H (sub 2) O .

creek claim

A claim that includes the bed of a creek. Under the statute of Oregon, a tract of land 100 yd (91.5 m) square, one side of which abuts on a creek or rather extends to the middle of the stream.

creek placers

Placers in, adjacent to, and at the level of small streams.

creek right

The privilege of diverting water for the purpose of working a creek claim. Syn: river right.


a. The slow and imperceptible movement of finely broken up rock material from higher to lower levels, usually due to alternate freezing and thawing, wetting and drying, or other causes. Also the material that has moved. CF: crown-in. See also: heaving; lift.

b. Slow deformation of a material that results from long application of a stress. Part of the creep is a permanent deformation, while part of the deformation is elastic and the specimen can recover. CF: thrust. c. See: drag. d. A very slow gradual movement of the drill-hoist drum when the brake is worn or not securely set. See also: heave.


An endless chain, with projecting bars at intervals that catch the car axles and haul them up an inclined plane. Creepers are used on the surface and around the pit bottom. They are also used on relatively flat roadways to retard or propel the cars as required.


Eng. The settling or natural subsidence of the surface caused by extensive underground mining.

creep limit

The maximum stress that a material can withstand without observable creep.

creep recovery

The gradual recovery of elastic strain when stress is released. Syn: elastic aftereffect.

creep strength

The load per unit area leading to a specified steady creep strain rate at a given temperature.


Scot. Smooth-faced nodules of shale or bind found occasionally in the roof of some coal seams. Also called greasy blaes.

creeshy clods

Peat which on drying breaks into irregular clods that burn with a clear bright flame like a lump of tallow or grease.


Said of mineral veins that have been deposited by springs. Etymol: Greek for spring. Obsolete.


Small-scale folding (wavelength of a few millimeters) that occurs chiefly in metamorphic rocks. CF: plication.


a. Red-and-white banded jasper from Shasta or San Bernadino County, CA.

b. A silicified rhyolite from Baja California.


As used in wood preservation, a distillate of coal tar produced by high-temperature carbonization of bituminous coal; it consists principally of liquid and solid aromatic hydrocarbons, and contains appreciable quantities of tar acids and tar bases; it is heavier than water; and has a continuous boiling range of at least 125 degrees C beginning at about 200 degrees C. Also called creosote oil; creosote distillate.

crept pillars

Eng. Pillars of coal that have passed through the various stages of creep.


a. The highest point on a given stratum in an anticline. See also: crestal plane; culmination.

b. See: crestline.

crestal plane

The plane formed by joining the crests of all beds in an anticline. See also: crest.


In an anticline, the line connecting the highest points on the same bed in an infinite number of cross sections. See also: crest.


Mixture of cresol isomers. Frother and froth stabilizing agent in flotation process. Emulsion stabilizer.


a. Applied to the third and final period of the Mesozoic Era. Extensive marine chalk beds were deposited during this period.

b. Of the nature of chalk or relating to chalk. c. System of strata deposited in the Cretaceous Period.


a. A wide breach or crack in the bank of a river or canal; esp. one in a natural levee or an artificial bank of the lower Mississippi River. Etymol: American French.

b. A wide, deep break or fissure in the Earth after an earthquake. c. A fissure in the surface of a glacier or icefall.


a. A shallow fissure in the bedrock under a gold placer in which small but highly concentrated deposits of gold may be found.

b. The fissure containing a vein. As employed in the Colorado mining statute relative to a discovery shaft, a crevice is a mineral-bearing vein. An older term.


Collecting gold that is in the crevices of a rock.

crew loader

In bituminous coal mining, one of a crew of loaders who shovels coal, blasting from working face, onto a conveyor that transports it from the underground working place to a point where it is loaded into mine cars.


A construction of timbering made by piling logs or beams horizontally one above another, and spiking or chaining them together, each layer being at right angles to those above and below it. See also: curb.


a. The construction of cribs, or timbers laid at right angles to each other, sometimes filled with earth, as a roof support or as a support for machinery.

b. The close setting of timber supports when shaft sinking through loose ground. The timber is usually square or rectangular and practically no ground is exposed. The method is also used for constructing ore chutes. See also: barring; close timbering; forepoling. c. A method of timbering used primarily to rectify a mistake of removing too great a percentage of the coal on the advance, and has the effect of replacing part of the coal. Some are made by using timbers in pigpen style; first laying timbers one way then placing other timbers across the first. This is continued until the area between the bottom and the roof is filled and wedged tight. Others are made by laying a layer of timbers first in one direction, then another layer across at right angles to the bottom layer. Space between the timbers in a layer varies according to requirements. The hollow type are generally filled with gob. Syn: penning.


A sieve.


Segments of oak to encircle the shaft.


a. A trigonal mineral, (Sr,La,Ce,Y)(Ti,Fe,Mn) (sub 21) O (sub 38) ; formerly misidentified as a variety of ilmenite.

b. The mineral group crichtonite, davidite, landauite, loeveringite, and senaite.


See: loose.


a. Som. See: clay gall.

b. Vertical joints affecting only the lower strata in a quarry. c. Joints in slate with an inclination opposite to the dip of the rock.


a. The flattening made by a crimper near the mouth of a blasting cap for holding the fuse in place.

b. To fix a detonator on blasting fuse by squeezing it with special pliers.


A tool specially made for fastening a cap to a fuse. See also: cap crimper.

crimson night stone

a. Purple fluorite from Idaho.

b. A variety of purple fluorite from Utah.


A small fold, usually a fraction of an inch in wavelength.

crinkled stone

A diamond with a shallowish, wavy, or rough surface.

crinoidal limestone

A marine limestone composed largely of fossil crinoid remains, such as plates, disks, stems, or columns.


A former name for the sagenite variety of quartz.


A mineral: SiO (sub 2) . It is a high-temperature polymorph of quartz and tridymite, and occurs as white octahedrons in the cavities of the fine-grained groundmasses of acidic volcanic rocks. Cristobalite is stable only above 1470 degrees C; it has a tetragonal structure (alpha-cristobalite) at low temperatures and an isometric structure (beta-cristobalite) at higher temperatures. CF: tridymite.


Grahamite, a mineral asphalt, from the Cristo Mine, Huasteca, Mexico.

critical angle

a. See: stalling angle.

b. The least angle of incidence at which there is total reflection when an optic, acoustic, or electromagnetic wave passes from one medium to another medium that is less refractive. CF: total reflection. c. The angle at which a ray of light in passing from a dense medium, such as a gemstone, into a rarer medium, such as air, is refracted at 90 degrees to the normal. Any rays reaching the interface at angles greater than the critical angle are unable to pass into the rarer medium and are totally reflected. d. The angle of incidence at which refracted light just grazes the surface of contact between two different media. e. The angle of refraction r for which sin r = 1/n, where n is the refractive index of a transparent material. CF: law of refraction.

critical area

In prospecting work, an area found to be favorable from geological age and structural considerations. Syn: favorable locality.

critical area of extraction

The area of coal required to be worked to cause a surface point to suffer all the subsidence possible from the extraction of a given seam. See also: subcritical area of extraction.

critical current

As applied to electric blasting caps, the minimum current that can be employed to fire detonators connected in series so that the chance of a misfire will be less than 1 in 100,000.

critical damping

The point at which the damping constant and the undamped frequency of a seismometer or seismograph are equal. After deflection, the moving mass approaches rest position without overswing and the motion is said to be aperiodic. See also: damping.

critical density

The density of a substance at its critical temperature and under its critical pressure; that density of a saturated, granular material below which, under rapid deformation, it will lose strength and above which it will gain strength.

critical diameter

a. For any explosive, the minimum diameter for propagation of a stable detonation. Critical diameter is affected by confinement, temperature, and pressure on the explosive.

b. The minimum explosive diameter which produces the propagation of a detonation wave at a stable velocity. It is affected by conditions of confinement, temperature and pressure on the explosive.

critical distance

In refraction seismic work, that distance at which the direct wave in an upper medium is matched in arrival time by that of the refracted wave from the medium below having greater velocity.

critical height

The maximum height at which a vertical or sloped bank of soil will stand unsupported under a given set of conditions (ASCE, 1958).

critical minerals

a. Minerals essential to the national defense, the procurement of which in war, while difficult, is less serious than those of strategic minerals because they can be either domestically produced or obtained in more adequate quantities or have a lesser degree of essentiality, and for which some degree of conservation and distribution control is necessary. See also: strategic minerals; essential mineral.

b. Minerals or mineral associations that are stable only under the conditions of one given metamorphic facies and will change upon change of facies. For example, in Eskola's greenschist facies, sericite and chlorite, albite and epidote are critical mineral associations because these combinations cannot persist out of the field of the greenschist facies, although any one of the individual minerals may be found in more than one facies.

critical point

A point representing a set of conditions (pressure, temperature, composition) at which two phases become physically indistinguishable; in a system of one component, the temperature and pressure at which a liquid and its vapor become identical in all properties. Syn: decalescence point.

critical pressure

a. The maximum feed pressure that can be applied to a diamond bit without damaging the bit or core barrel. CF: total critical load.

b. The minimum load, in pounds per effective diamond cutting point in a bit face, at which the diamonds cut the rock. Below this load, the diamonds slide on the rock surface without penetrating the rock, and the diamonds polish, become dull, and are rendered unfit for further use in that particular ground unless reset. c. The pressure required to condense a gas at the critical temperature, above which, regardless of pressure, the gas cannot be liquefied.

critical slope

The maximum angle with the horizontal at which a sloped bank of soil or given height of soil will stand unsupported. Syn: angle of repose; angle of rest.

critical temperature

a. The temperature of a system at its critical point; for a one-component system; that temperature above which a substance can exist only in the gaseous state, no matter what pressure is exerted. See also: temperature.

b. Transformation temperature. c. The temperature at which a change takes place in the physical form of a substance; e.g., the change of diamond to the amorphous form of carbon begins at a temperature of 1,800 degrees F (982 degrees C) in the presence of oxygen. d. Synonymous for critical point if the pressure is constant. e. The temperature above which the vapor phase cannot be condensed to liquid by an increase in pressure. See also: temperature.

critical velocity

a. Reynolds' critical velocity is that at which fluid flow changes from laminar to turbulent, and where friction ceases to be proportional to the first power of the velocity and becomes proportional to a higher power.

b. Kennedy's critical velocity is that of fluid flow in open channels that will neither deposit nor pick up silt. c. Belanger's critical velocity is that condition of fluid flow in open channels for which the velocity head equals one-half the mean depth.

critical void ratio

The void ratio corresponding to the critical density.