Appendix:Dictionary of Mining, Mineral, and Related Terms/C/4

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An opaque variety of andalusite containing black carbonaceous impurities arranged in a regular manner so that a section normal to the longer axis of the crystal shows a black Maltese cross. It has long been used for amulets, charms, and other inexpensive novelty jewelry. Syn: cross-stone; crucite; macle.

chiastolite slate

A rock formed by contact metamorphism of carbonaceous shale, characterized by prominent cleavage or schistosity and the presence of conspicuous chiastolite crystals in a fine-grained groundmass.


An Alaskan term for fine gravel 1/2 in (1.27 cm) or less in diameter.

Chiddy Assay

Cupellation assay, for gold content of barren cyanide solution. The gold (and silver) is precipitated together with metallic lead as sponge on aluminum. This metal is cupeled, and the gold prill is weighed.


A timber used in making a crib.


A monoclinic mineral, FeAl(PO (sub 4) )(OH) (sub 2) .H (sub 2) O ; forms a series with eosphorite.

Chilean lapis

A pale- to light-blue lapis lazuli from Chile. See: lazurite; lapis matrix.

Chilean mill

A mill having vertical rollers running in a circular enclosure with a stone or iron base or die. There are two classes: (1) those in which the rollers gyrate around a central axis, rolling upon the die as they go (the true Chile mill), and (2) those in which the enclosure or pan revolves, and the rollers, placed on a fixed axis, are in turn revolved by the pan. It was formerly used as a coarse grinder, but is now used for fine grinding.


An earthy, secondary lead, zinc, and copper vanadate; occurs near Arqueros, Chile; related to psittacinite. See also: mottramite.


An amorphous mixture(?) containing silver and bismuth.

Chile saltpeter

A former name for nitratine.


a. A metal insert imbedded in the surface of a sand mold or core or placed in a mold cavity to increase the cooling rate at that point.

b. White iron occurring on a gray iron casting, such as the chill in a wedge test. c. To harden by suddenly cooling. d. Derb. To test the roof with a tool or bar to determine its safety.

chill casting

Pouring molten metal into molds so made that it comes into contact at desired places with metal; cooling is thus accelerated, and special hardness is imparted.

chill crystal

Small crystal formed by the rapid freezing of molten metal when it comes into contact with the surface of a cold metal mold.

chilled casting

A casting made by contacting it with something that will rapidly conduct the heat from it, such as a cool iron mold, or by sudden cooling by exposure to air or water.

chilled contact

That part of a mass of igneous rock, near its contact with older rocks, that is finer grained than the rest of the mass, because it cooled more rapidly.

chilled dynamite

The condition of dynamite when subjected to a low temperature not sufficient to congeal it, but which seriously affects the strength of the dynamite.

chilled shot

In hard-rock boring with an adamantine or Calyx drill, chilled iron or steel pellets that are driven by the drill bit and do the actual abrasive cutting.

chilled-shot drill

See: shot drill.

chilled-shot drilling

A method of rotary drilling in which chilled steel shot is used as the cutting medium.


a. An ore shoot or pipe. See also: chute.

b. A term used for limestone pinnacles bounding zinc ore deposits. c. A vertical or nearly vertical staple shaft between a lower and an upper coal seam. d. An orebody that is roughly circular or elliptical in horizontal cross section, but may have great vertical extent. e. A restricted section in a lode; rising steeply and unusually rich. See also: pipe. f. A cylindrical vent for volcanic rock.

chimney effect

See: stack effect.

chimney rock

a. A column of rock standing above its surroundings, such as an igneous rock filling a pipe-shaped vent.

b. Gulf States. A local name for any rock soft enough when quarried to be cut or sawn readily and refractory enough for domestic chimneys, which may harden on exposure to the air; e.g., some limestone, siliceous bauxite clay, or soapstone.

chimney work

Mid. A system of working beds of clay ironstone in patches 10 to 30 yd (9.1 to 27.4 m) square and 18 to 20 ft (5.5 to 6.1 m) thick. The bottom beds are first worked out; then miners work the higher ones by standing upon the fallen debris. CF: overhand stoping.

china clay

A commercial term for kaolin obtained from china-clay rock after washing, and suitable for use in the manufacture of chinaware.

china-clay rock

a. Cornwall stone.

b. Granite in its most kaolinized form, in which the feldspar is transformed into kaolinite and the rock is so soft that it is readily broken in the fingers.

chinaman chute

Mine opening over the haulage level through which ore from the stope above is drawn to waiting trucks as planking is removed. Usually, an opening between stulls below the shrinkage stope.

Chinaman pebble

N.Z. A pebble or boulder made from a conglomerate of quartz pebbles cemented by chalcedony. Jaspilite, quartz, and Chinaman pebbles are found in many places.

China metal

a. York. Shale baked to a hard, white, coarse, porcellaneous substance.

b. Porcelain.

china stone

a. Partially kaolinized granite containing quartz, kaolin, and sometimes mica and fluorite. It is harder than china-clay rock and is used as a glaze in the manufacture of china. Syn: petuntze. CF: Cornish stone.

b. A fine-grained, compact carboniferous mudstone or limestone found in England and Wales.


a. Scot. A gravel free from dirt. See also: shingle.

b. That portion of a coal seam stowed away in the goaves to help support the mine roof.


A tetragonal mineral, Na (sub 5) Al (sub 3) F (sub 14) ; massive; granular; occurs with cryolite.


a. Small fragment of a diamond, usually thin and tabular in shape.

b. To break small fragments from the surface of a diamond or other material. c. Small, angular, and generally flat pieces of rock or other materials. d. An imperfection due to breakage of a small fragment out of an otherwise regular surface. e. A small fragment from a crystal; specif. a diamond chip. f. A piece of rock to be cut into a thin section for microscopic examination.

chip blasting

Shallow blasting of ledge rock.

chip breaker

a. A notch or groove in the face of a tool parallel to the cutting edge, to break the continuity of the chips.

b. A step formed by an adjustable component clamped to the face of a cutting tool.


a. When referring to the character of diamond wear, it denotes loss of diamond due to chips and fragments having been broken away from the body of the diamond.

b. A surface pitted by loss of material in the form of chips.


a. Loosening of shallow rock by light blasting or airhammers.

b. The process of handsetting diamond fragments in a bit.


Crushed angular stone fragments ranging from 1/8 to 1 in (0.32 to 2.54 cm) in size. See also: aggregate.

chip sample

A regular series of ore chips or rock chips taken either in a continuous line across an exposure or at uniformly spaced intervals.

chip sampling

a. The taking of small pieces of ore or coal, with a small pick, along a line or at random, across the width of a face exposure. The samples are usually taken daily and often confined to exploration. Reasonable care is taken to chip a weight of material that corresponds to the length of sample line. See also: bulk sample.

b. A variant of channel sampling, in which, owing to extreme hardness of rock, shape of deposit, or other working difficulty, a true channel sample cannot be taken. Often used in preliminary prospecting.


Symmetrical handedness. A mirror or center of symmetry changes the chirality of asymmetric units. CF: improper.


Bat guano.


a. A tool of great variety whose cutting principle is that of the wedge.

b. The steel cutting tool used in percussive boring. It ranges from 6 to 12 in (15.2 to 30.5 cm) in length with variously shaped bits to suit the nature of the ground. The chisel is made to strike a series of blows at the bottom of a borehole. Water or mud is circulated to convert the chippings into sludge and to keep the chisel cool.

chisel bit

a. See: chopping bit.

b. A percussive-type, rock-cutting bit having a single, chisel-shaped cutting edge extending across the diameter and through the center point of the bit face. Also called chisel-edge bit; chisel-point; Swedish bit.

chisel draft

The dressed edge of a stone, which serves as a guide in cutting the rest.


See: shiver.


An orthorhombic mineral, Na (sub 2) BeSi (sub 2) O (sub 6) ; occurs on the Kola Peninsula, Russia.


An arsenic-deficient variety of nickel-skutterudite. Also spelled cloanthite. Syn: white nickel ore.


A trigonal mineral, AlCl (sub 3) .6H (sub 2) O ; occurs in acid fumaroles on Mt. Vesuvius, Italy.


A monoclinic mineral, Ca (sub 5) (PO (sub 4) ) (sub 3) Cl ; apatite group.


An isometric mineral, 4[AgCl] ; sectile; forms waxy white, yellow, or pearl-gray incrustations, darkening to violet on exposure to light; a supergene mineral occurring in silver veins; an important source of silver. Formerly called cerargyrite. Syn: horn silver. CF: iodargyrite.


A mottled green variety of pumpellyite used as a semiprecious stone; forms grains, small nodules, or a radial, fibrous structure in geodes in mafic igneous rocks; resembles prehnite; occurs in the Lake Superior region (esp. on Isle Royale).

chlorate explosive

Explosive with a potassium chlorate base, such as the French cheddite, which contains about 80% potassium chlorate and 5% castor oil, with dinitrotoluene constituting nearly all the remainder. Chlorate explosives are characterized by a hot flame on detonation.

chlorate powder

A substitute for blackpowder in which potassium chlorate is used in place of potassium nitrate.


a. A miner's or prospector's term for an ore containing silver chloride.

b. A compound of chlorine with another element or radical. A salt or ester of hydrochloric acid.


Mining thin veins.


An ore treatment using chlorine to produce a metal chloride.


To convert into chloride; applied to the roasting of silver ores with salt, preparatory to amalgamation.

chloridizing roasting

The roasting of sulfide ores and concentrates, mixed with sodium chloride, to convert the sulfides to chlorides.

chlorination process

The process in which auriferous ores are first roasted to oxidize the base metals; then saturated with chlorine gas; and finally treated with water, which removes the soluble chloride of gold, to be subsequently precipitated and melted into bars.


A machine for feeding either liquid or gaseous chlorine to a stream of water.


A common nonmetallic halogen element, found in the combined state only, chiefly with sodium as common salt (NaCl). Symbol, Cl. A greenish-yellow irritating toxic gas with a disagreeable odor; a respiratory irritant. Used for producing safe drinking water, paper products, dyestuffs, textiles, petroleum products, medicines, antiseptics, insecticides, foodstuffs, solvents, paints, plastics, and many other consumer products.


a. The total amount in grams of chlorine, iodine, and bromine contained in 1 kg of seawater, assuming that the bromine and iodine have been replaced by chlorine.

b. The number giving the chlorinity in grams per kilogram of seawater sample is identical with the number, giving the mass in grams of atomic weight silver just necessary to precipitate the halogens in 0.3285233 kg of the seawater sample.


a. The mineral group chamosite, clinochlore, cookeite, gonyerite, nimite, orthochamosite, pennantite, and sudoite.

b. Chlorites are associated with and resemble micas (the tabular crystals of chlorites cleave into small, thin flakes or scales that are flexible, but not elastic like those of micas); they may also be considered as clay minerals when very fine grained. Chlorites are widely distributed, esp. in low-grade metamorphic rocks, or as alteration products of ferromagnesian minerals.

chlorite schist

A schist in which the main constituent, chlorite, imparts a schistosity by parallel arrangement of its flakes. Quartz, epidote, magnetite, and garnet may be accessories, the last two often as conspicuous porphyroblasts.

chlorite slate

A schistose or slaty rock composed largely of chlorite.

chloritic sand

A sand colored green by sand-size chlorite grains.

chloritic schist

A schist containing chlorite.


The replacement by, conversion into, or introduction of chlorite.


A monoclinic or triclinic mineral, (Fe,Mg,Mn) (sub 2) Al (sub 4) Si (sub 2) O (sub 10) (OH) (sub 4) ; dull green to gray-black; occurs in masses of brittle folia in metamorphosed argillaceous sedimentary rocks. It is related to the brittle micas.


A trigonal mineral, K (sub 4) MnCl (sub 6) ; occurs in yellow rhombohedra.


See: baeumlerite.


a. A dark green, nearly black variety of jadeite.

b. A crystal solution of roughly equal amounts of diopside, jadeite, and acmite.


a. A former name for nontronite.

b. A greenish variety of common opal from Silesia, Poland.


A mineral closely related to chlorite in composition and found in the groundmass of tholeiitic basalts where it occupies interstices between feldspar laths, forms pseudomorphs after olivine, or occurs in veinlets and amygdules. The fresh mineral is pale green, but when weathered, it may be dark green, brown, or red.


A variety of fluorite that exhibits bright-green phosphorescent light if heated. Also called cobra stone.


A monoclinic mineral, (Mn,Mg) (sub 3) Zn (sub 2) (AsO (sub 4) )(OH,O) (sub 6) ; occurs in elongated gray-green crystals at Franklin, NJ.


The yellowing of the leaves of plants, sometimes caused by a deficiency of iron necessary in the formation of chlorophyll. Has been useful as a guide to ore since nickel, copper, cobalt, chromium, zinc, and manganese are all antagonistic to iron in plant metabolism. Also may indicate where such toxins have been added to soil by industrial or other human activity.


The number expressing chlorinity as grams per liter. Obtained by multiplying the chlorinity of a sample by its density at 20 degrees C.


A grass-green variety of spinel containing copper.


An orthorhombic mineral, K (sub 2) Cu(SO (sub 4) )Cl (sub 2) ; occurs in bright-blue crystalline crusts on lava, an alteration product at Mt. Vesuvius, Italy.


A green orthorhombic hydrated arsenate of copper. CF: mixite.


A monoclinic mineral, Pb (sub 3) CuCl (sub 2) (OH) (sub 2) O (sub 2) ; dull-olive or pistachio green.


See: utahlite.


a. A square pillar for supporting the roof; constructed of prop timber laid up in alternate cross-layers, in log-cabin style, the center being filled with waste. Sometimes called crib. See also: cog; hydraulic chock.

b. Type of longwall-mining roof support. c. One of two blocks of hardwood placed across or between rails to prevent tubs, cars, or wagons from running down an incline.

chock and block

Newc. Tightly filled up.

chock block

Piece of wood, square or rectangular in cross section, usually made of oak, ash, or other hardwood. Also used to denote a shaped piece of wood provided with a handle and designed for placing between the rails to hold back a tub or set of tubs.

chock hole

A small depression dug in the earth in which a wheel of a truck-mounted drill rig is set to prevent the drill from moving.


The supporting of undercut coal with short wedges or chocks.


An English term for chocks, or blocks spiked into the corner of a shaft to form a bearing for the side-walling piece, or the blocks used in headings to separate the cap and poling board. See also: collaring.


a. In crushing practice, a stoppage of the downward flow in a rock-crushing chamber. See also: choke point.

b. A point in a cave or at the base of a pitch blocked by the influx of clay, sand, gravel, or similar material.

choke crushing

A recrushing of fine ore due to the fact that the broken material cannot exit a machine before it is again crushed. CF: free crushing.


a. A mine atmosphere that causes choking or suffocation due to insufficient oxygen. As applied to "air" that causes choking, does not mean any single gas or combination of gases.

b. A name sometimes given in England to carbon dioxide. See also: blackdamp; damp.

choke fed

In comminution, rolls are choke fed when fed all of the material that they will take. The product of choke-fed rolls is never so uniform as when free feeding is used. Choke feeding is used only on feed of diameter about 1/4 in (0.6 cm) or less. CF: free fed.

choke feed

A feeding arrangement in which the potential rate of supplying material at the feed point exceeds the rate at which the conveyor will remove material.

choke feeding

As deliberately used in roll crushing of ore, feed at a rate greater than can be discharged at the set of the machine, so that the rolls are sprung apart, the angle of nip is increased, and the product contains oversize.

choke point

Bottleneck of any crusher.


A chain or cable so fastened that it tightens on its load as it is pulled.


Stoppage of flow, due to obstructed discharge, sticky material, packed and compacted fines, or bad control.


A monoclinic mineral, (Mg,Fe) (sub 5) (SiO (sub 4) ) (sub 2) (F,OH) (sub 2) ; humite group; commonly occurs in contact-metamorphosed dolomites. Also spelled condrodite.


An intrusive mass that is so irregular in form and its relationship to the invaded formations is so obscure that it cannot be designated a dike, sill, or laccolith.


a. To break up and drill through boulders, other rock, or lost core encountered in sinking a drivepipe or casing through overburden. It is done by impact produced by lifting and dropping a chopping-bit-tipped string of drill rods.

b. Som. A local term for fault.

chop ahead

To break up boulders and other rock material below the bottom of casing or drivepipe by using a chopping bit attached to drill rods. See also: chop.

chop feeder

A feeder in which a power-operated, swinging quadrant gate delivers material at a predetermined rate. The action is similar to a reciprocating plate feeder.


A term used to describe the digging action of a dragline when excavation takes place with the bucket heel above the line of the cutting lip. This term is usually used when referring to an operating method in which the dragline bucket excavates above the line of the fairlead and fills above tub level.

chopping bit

A steel, chisel-shaped cutting-edged bit designed to be coupled to a string of drill rods and used to fragment, by impact, boulders, hardpan, and lost core in a borehole. Also called chisel bit; chisel-edge bit; chisel-point bit; long-shank chopping bit. CF: cross-chopping bit.

chordal effect

The effect produced by the chain joint centers being forced to follow arcs instead of chords of a sprocket pitch circle.

chordal pitch

The length of one side of the polygon formed by the lines between the joint centers as a chain is wrapped on a sprocket. It is a chord of the sprocket pitch circle and is equal to the chain pitch.


A general term for a group of mixed rocks, which are the result of the injection of the crystallization products of intruding magmas into, and/or the mixture of such material with, the enclosing rocks, sedimentary or metamorphic. There are several varieties. The term is not widely used. CF: migmatite.


See: chews.

C/H ratio

See: carbon-hydrogen ratio.


A butyraceous, greenish-yellow to wax-yellow hydrocarbon from Wettin, Saxony, Germany. It has a specific gravity of less than 1 and is soft at 55 to 60 degrees C.

Christiansen effect

In optical mineralogy, a dispersion phenomenon in which the boundary of a mineral grain (Becke line) immersed in a liquid of the same index of refraction appears blue on one side and red to orange on the other. See also: dispersion.


See: cristobalite.


A salt or ester of chromic acid; a compound containing the radical (CrO (sub 4) ) (super 2-) .

chromatic aberration

In microscope lenses, the splitting of white light to form two images, one red and the other blue. See also: aberration.

chromatic color

A hue, as distinguished from white, black, or any tone of gray. Opposite of achromatic color.


A tetragonal mineral, CaCrO (sub 4) ; forms finely crystalline citron-yellow crusts from clefts in limestones.


An instrument for analyzing gases and vapors from liquids with boiling points up to 300 degrees C. The gas chromatograph often arranges the molecules of a gas in increasing size, and as each group emerges from the column, a detector measures the quantity of each. Since all the molecules of one type emerge after the same time interval, it is possible to identify quickly the constituents present.

chromatographic analysis

Separation of components of mixture into zones, one or more of which can be identified by color, etc.: (1) by adsorption column, adsorbing from solute in a tube packed with cellulose, alumina, lime, etc.; (2) by electrochromatography, passing electricity across a column or paper strip down which solvent mixture is flowing, causing migration to the side of a flow line; (3) by electrophoresis, using electric current to aid migration; and (4) by paper partition, separation into bands as suitable solvent flows past a drop of solution, which contains compounds (qualitative and quantitative analysis).


A chemical process of separating closely related compounds by permitting a solution of them to filter through an absorbent so that the different compounds become absorbed in separate colored layers comprising a chromatogram.


A term commonly used to indicate ore of chromium, consisting esp. of the mineral chromite or chromium-bearing minerals, such as chrome mica or chrome diopside.

chrome antigorite

A variety of antigorite containing some chromium.

chrome brick

A refractory brick manufactured substantially or entirely of chrome ore.

chrome chert

A variety of chert that has replaced the silicate minerals of a chromite peridotite, the more resistant chromite grains remaining unaltered in the siliceous matrix.

chrome diopside

a. A variety of diopside. Dark-green specimens are seldom either transparent or cut as gems.

b. A bright emerald-green variety of diopside containing a small amount of Cr (sub 2) O (sub 3) .

chrome garnet

See: uvarovite.

chrome idocrase

An emerald-green variety of vesuvianite containing chromium; occurs at Black Lake, Quebec, Canada; and Ekaterinburg, Ural Mountains, Russia. Syn: chrome vesuvian.

chrome iron ore

See: chromite.

chrome mica

See: fuchsite.

chrome ocher

A chromiferous clay; specif. a bright-green clay material containing 2% to 10.5% Cr (sub 2) O (sub 3) .

chrome refractory

Refractory consisting essentially of refractory-grade chrome ore bonded chemically or by burning. Chrome refractories are nearly chemically neutral, but may react with strong acids or bases.

chrome spinel

Another name for the mineral picotite, a member of the spinel group. See: chromian spinel.

chrome tourmaline

A variety of tourmaline found in the Ural Mountains, Russia, and Maryland.

chrome vesuvian

See: chrome idocrase.

chromian spinel

A variety of spinel containing chromium, (Mg,Fe)(Al,Cr) (sub 2) O (sub 4). Formerly called picotite. See: chrome spinel.

chromic iron

See: chromite.


An isometric mineral, 8[FeCr (sub 2) O (sub 4) ] ; spinel group; dimorphous with donathite; forms crystal-solution series with magnesiochromite in the chromite series of the spinel group, and with hercynite; rarely occurs as a pure end member. End-member chromite contains 68% Cr (sub 2) O (sub 3) , but natural minerals do not commonly exceed 50%. Occurs in metallic black octahedral crystals; weakly to moderately ferrimagnetic; an accessory in, or layers in, mafic and ultramafic rocks; also in black sands, the major source of chromium. Syn: chrome iron ore.


a. A rock composed chiefly of the mineral chromite.

b. A mixture of chromite with magnetite or hematite.


An isometric mineral, Cr ; rare; occurs in contact zones between ultramafic rocks and marble.

chromium garnet

See: uvarovite.


In mineral identification, a polished section is placed in contact with photographic paper, a current is passed, and ions migrating to the paper are developed so as to produce a color print suitable for microscrutiny. It resembles sulfur printing.


A red variety of wulfenite, containing some chromium.


An apparatus for electrically recording explosion phenomena with a continuous time record.


See: time-stratigraphic unit.

chronolithologic unit

Time-rock unit. See also: time-stratigraphic unit.

chronostratic unit

See: time-stratigraphic unit.

chronostratigraphic unit

See: time-stratigraphic unit.


An orthorhombic mineral, BeAl (sub 2) O (sub 4) ; vitreous; green, brown, yellow, or red (alexandrite variety appears emerald green in sunlight, but red by incandescent light); occurs in granites, granite pegmatites, schists, and alluvial deposits; a gemstone. Gem varieties: alexandrite, chrysopal, cymophane, and golden beryl. Known as cat's-eye when it has chatoyancy. Syn: cymophane. See also: dichroism; beryllium aluminate; chrysopal.


A monoclinic mineral, (Cu,Al) (sub 2) H (sub 2) Si (sub 2) O (sub 5) (OH) (sub 4) .nH (sub 2) O ; cryptocrystalline or amorphous; soft; bluish green to emerald green; forms incrustations and thin seams in oxidized parts of copper-mineral veins; a source of copper and an ornamental stone.

chrysocolla quartz

A translucent chalcedony colored by chrysocolla.


A yellowish-green, sometimes brownish or reddish, iron-magnesium silicate. A common mineral in basalt and diorite. When used as a gem, it is called peridot. The name has at various times been applied to topaz, prehnite, and apatite, but is now used only to mean olivine. See also: olivine.

chrysolite cat's-eye

Chrysoberyl cat's-eye.


A pale yellowish-green variety of beryl.


a. A translucent variety of common opal colored apple green by the presence of nickel.

b. See: chrysoberyl. c. A gemstone trade name for opalescent chrysolite (olivine). See also: prasopal.


a. An apple-green or pale yellowish-green variety of chalcedony containing nickel and valued as a gem. See also: green chalcedony.

b. A misleading name used in the gem trade for a green-dyed chalcedony having a much darker color than natural chrysoprase.


A monoclinic mineral (clinochrysotile), or orthorhombic mineral (orthochrysotile, parachrysotile), [Mg (sub 6) (OH) (sub 8) Si (sub 4) O (sub 10) ] ; serpentine group; forms soft, silky white, yellow, green, or gray flexible fibers as veins in altered ultramafic rocks; the chief asbestos minerals. (Not to be confused with chrysolite.) Syn: Canadian asbestos; serpentine asbestos.

chrysotile asbestos

A fibrous variety of serpentine.


The part of a diamond or rotary drill that grips and holds the drill rods or kelly and by means of which longitudinal and/or rotational movements are transmitted to the drill rods or kelly. See also: three-jaw chuck.

chuck block

In stamp milling, the wooden block or board that is attached to the bottom of the screen so as to raise the depth of the issue and act as a false lip to the mortar.


A device for automatic rerailing of tubs or cars. Also called ramp; rerailer.

chuckie stone

One of the pebbles or cobbles of sedimentary rock or of igneous rock occurring as an inclusion in a coalbed. One explanation for their occurrence is that they were attached to roots of floating trees rafted into the swamp during periods of high water.


Caliche deposit in Chile composed mainly of sodium sulfate.


A triclinic mineral, (Mg,Zn) (sub 5) H (sub 2) (AsO (sub 4) ) (sub 4) .10H (sub 2) O .


An isometric mineral, Ca (sub 3) (Ce,Y)Al (sub 2) (SO (sub 4) )F (sub 13) .10H (sub 2) O ; a rare-earth mineral in the Kara-Oba molybdenite deposit, central Kazakhstan, and the Clara Mine, Oberwolfach, Germany.


Malaysia. Heavy hoe used to stir and loosen a bed when sluicing alluvial tin gravels.


Built up with large lumps of coal to increase the capacity of the car. Also called built-up.

chunker I

In bituminous coal mining, a laborer who hand loads large lumps of coal into cars at working places in a mine.

chunker II

In bituminous coal mining, a laborer who arranges large lumps of coal uniformly on flatcars as they are loaded at the mine surface.


See: mendipite.


A monoclinic mineral, YPO (sub 4) .2H (sub 2) O . Formerly called weinschenkite.


A long iron rod used to hand bore shotholes in soft material, such as coal.

churn drill

a. Portable drilling equipment, usually mounted on four wheels and driven by steam-, diesel-, electric-, or gasoline-powered engines or motors. The drilling is performed by a heavy string of tools tipped with a blunt-edge chisel bit suspended from a flexible manila or steel cable, to which a reciprocating motion is imparted by its suspension from an oscillating beam or sheave, causing the bit to be raised and dropped, thus striking successive blows by means of which the rock is chipped and pulverized and the borehole deepened; also, the act or process of drilling a hole with a churn drill. Also called American system drill; blasthole drill; cable drill; cable-system drill; churn-drill rig; rope-system drill; shothole drill; spudder; spud drill; wet drill. See also: percussion drill. Syn: cable-tool drill.

b. A long iron bar with a cutting end of steel, used in quarrying, and worked by raising and letting it fall. When worked by blows of a hammer or sledge, it is called a jumper or jump drill.

churn-drill operator

In mining and in the quarry industry, one who drills holes with a churn (cable) drill in rock and overlying ground of open-pit mines or quarries to obtain samples, or to provide holes in which explosives are detonated to break up a solid mass. Syn: blasthole driller; blasting hole well driller.

churn-drill rig

See: churn drill.

churn shot drill

A boring rig that combines both churn and shot drillings. The churn drill is used for rapid penetration in barren ground where no core is required. The shot drill is used for taking cores along important rock formations.


a. A channel or shaft underground, or an inclined trough aboveground, through which ore falls or is shot by gravity from a higher to a lower level. Also spelled shoot.

b. A crosscut connecting a gangway with a heading. c. A ditch or inclined timber through which the overflow water or mud from a borehole is conducted from the collar of the hole to the sump. The chute may be fitted with baffles and screens to cause the cuttings to settle before reaching the sump. Syn: canal; ditch. d. A body of ore, usually of elongated form, extending downward within a vein (ore shoot). See also: chimney; shoot. e. A trough operated mechanically in loading coal underground. Syn: rock chute. f. A string of rich ore in a lode (used instead of shoot). g. Stockpile withdrawing system, such as a belt conveyor. h. A metal trough in a breaker, along which the coal slides by gravity. i. A steep, three-sided steel tray for the passage of coal or ore from a conveyor into mine cars. It is designed to minimize degradation and spillage of materials. See also: loading chute. j. Ore pass connecting a stope with the haulage level. k. A high-velocity conduit for conveying to a lower level. Syn: course of ore.

chute boss

In coal mining, a foreperson who supervises the loading and drawing of coal into and out of chutes, esp. where coal is mined from inclined beds.

chute caving

The method involves both overhand stoping and ore caving. A chamber is started as an overhand stope from the head of a chute and is extended up until the back weakens sufficiently to cave. The orebody is worked from the top down in thick slices, each slice being, however, attacked from the bottom and the working extending from the floor of the slice up to an intermediate point. The cover follows down upon the caved ore. Also called caving by raising; block caving into chutes.

chute checker

In metal mining, one who keeps a record of the amount of ore drawn from each raise or chute in an orebody being mined by the caving method (lower part of orebody is mined and developed with a system of chutes so that the remaining ore that sloughs, or caves, from lack of support can be drawn off). Also called tallyman.

chute drawer

See: chute loader.

chute loader

a. In metal and nonmetal mining, a laborer who loads ore or rock into mine cars underground by opening and closing chute gates. Also called chute drawer; chute man; chute puller; chute trammer; chute tapper.

b. In the quarry industry, one who loads crushed rock from bins into trucks or railroad cars by opening and closing the chute or bin gates by hand or by means of a lever. Also called car loader.

chute operator

In the quarry industry, a laborer who loads barges with crushed rock by operating a hand winch to lower a chute through which crushed rock flows from a bin.

chute system

A method of mining by which ore is broken from the surface downward into chutes and removed through passageways below. See also: glory-hole system.

chute trammer

See: chute loader.


A marshy area where the ground is wet because of the presence of seepage or springs, often with standing water and abundant vegetation. The term is commonly applied in arid regions such as the Southwestern United States. Etymol: Spanish cienaga, marsh, bog, miry place.

ciment fondu

A slow-setting, rapid-hardening cement containing 40% lime, 40% alumina, 10% silica, and 10% impurities; used in cementing drill holes. Sometimes called bauxite cement.


A white, grayish, or reddish hydrosilicate of aluminum; soft and claylike or chalklike in appearance.


a. A loose volcanic fragment that may range from 4 to 32 mm in diameter. Such fragments are usually glassy or vesicular.

b. A small (1- to 4-cm), commonly vesicular, fragment of lava projected from an erupting volcano; coarser than volcanic ash but smaller than a volcanic bomb. c. A juvenile vitric pyroclastic fragment that falls to the ground in an essentially solid condition. d. Slag, particularly from an iron blast furnace. e. A scale thrown off in forging metal. CF: lapilli.

cinder block

A block closing the front of a blast furnace and containing the cinder notch.

cinder breakout

The slag within a furnace escaping through the brickwork; caused by erosion, corrosion, or softening of brick by heat.

cinder coal

a. Coal that has been cindered by heat from an igneous intrusion. Many coal seams have been affected in this way in Scotland and in Durham, England. See also: metamorphism.

b. Aust. A very inferior natural coke, little better than ash. See also: natural coke.

cinder cooler

In a blast furnace, a watercooled casting, usually of copper, that is pressed into the cinder notch.

cinder fall

The dam over which the slag from the cinder notch of a furnace flows.

cinder notch

The furnace hole, about 1.5 to 2 m above the iron notch and 1 m below the tuyeres, through which slag is flushed two to three times between casts. See also: cinder tap.

cinder pig

Pig iron made from a charge containing a considerable proportion of slag from puddling or reheating furnaces.

cinder pit

Large pit filled with water into which molten cinder is run and granulated at cast or flush.

cinder plate

See: bloomery.

cinder runner

A trough carrying slag from a skimmer or cinder notch to a pit or ladle. See also: cinder notch.

cinder tap

The hole through which cinder is tapped from a furnace. Also called Lurmann front.

cinder tub

A shallow iron truck with movable sides into which the slag of a furnace flows from the cinder runner.


A trigonal mineral, 3[HgS] ; trimorphous with hypercinnabar and metacinnabar; forms brilliant red acicular crystals and red to brownish-red or gray masses; soft; sp gr, 8.1; occurs in impregnations and vein fillings near recent volcanic rocks and hot springs, alluvial deposits; the chief source of mercury. Syn: cinnabarite. See also: vermillion; vermilion.


See: cinnabar.

cinnabar matrix

A term applicable to various varieties of minerals containing numerous inclusions of cinnabar but esp. to a Mexican variety of jasper.


See: cinnamon stone.

cinnamon stone

a. Grossularite, a lime garnet. See also: essonite; hessonite; hyacinth.

b. See: grossular.


A European term for a marble rich in silicate minerals and characterized by layers rich in micaceous minerals.

CIPW classification

See: norm system.

CIPW system

See: norm system.


a. In the central United States, a nearly circular lead and zinc deposit developed in clayey chert breccias in old sinkholes in Paleozoic limestone or in dolomite (broken ground).

b. In a grader, the rotary table that supports the blade and regulates its angle.

circle cutting drill

a. A pneumatic drill carried on rotating arms. Used to cut grindstones and pulpstones from a quarry.

b. See: ditcher.

circle haul

In strip mining, a haulage system in which the empty units enter the mine over one lateral and leave, loaded, over the lateral nearest the tipple. This system is utilized where laterals are built into the mine from the main road, whether outside the outcrop or on the high-wall side of the mine workings. This system reduces the haul on the coal surface to a minimum, except where there are only two laterals, one at each end of the workings.

circle reverse

The mechanism that changes the angle of a grader blade.

circle spout

Eng. A trough or gutter around the inside of a shaft to catch the water running down the sides; a garland.

circuit breaker

These differ from straight overcurrent relays in that they are primarily used for ground protection. They are designed to measure fault current in one or two sections. Whether faults will cause flow in one or two directions is determined by system conditions. The two-directional relay is used on transmission lines where ground-fault currents flow in either direction. These relays provide directional as well as overcurrent protection. Other directional relays provide phase protection.


Circular galleries made at different levels in a mine that enable empty trucks to be pushed out of the cage on one side while full ones are pushed in on the other side, thus ensuring a more rapid journey of the cage. Circuits also aid air circulation. Syn: roundabouts.

circuit tester

See: blasting galvanometer.

circular arch

A roadway support consisting of an H-section girder of circular form and usually made in three parts. The joints are secured by fishplates and bolts. This type of steel arch is useful for withstanding pressures from roof, sides, and floor. With close lagging between the rings, the finished roadway resembles a tube. See also: steel arch.

circular bin discharger

A revolving cone with feeder fingers around the base periphery connected at the apex through a universal joint to a revolving arch breaker arm.

circular cutting drill

See: ditcher.

circular grading table

See: rotary sorting table.

circular picking table

An apparatus used for the same purpose as a picking belt and consisting of a flat horizontal rotating annular plate. See also: picking belt.

circular shaft

A shaft excavated as a cylinder. The circular shaft is equally strong at all points; convenient for concrete lining and tubbing, both of which can be made relatively watertight; and offers the least resistance to airflow.

circular slip

A type of landslide that may occur in embankments or cuttings in clay or homogeneous earth. See: slip surface of failure.

circular tunnel kiln

The same as a straight tunnel kiln, except that it has a movable, circular platform instead of cars.

circulating fluid

Fluid pumped into a borehole through the drill stem, the flow of which cools the bit, washes away the cuttings from the bit, and transports the cuttings out of the borehole. See also: reverse circulation. Also called circulation fluid; circulation medium; drill fluid; drilling fluid.

circulating head

A casing-to-drill-rod coupling. When attached to the top of the casing, it is used during the process of pumping cement slurries or circulating water through the casing, forcing the fluid to flow out of the casing into the drill hole between the outside of the casing and the walls of the borehole. Also called stuffing box; tight head.

circulating load

a. In mineral processing, use of a closed circuit to check mineral issuing from a specific treatment and to return to the head of the treatment those particles that do not satisfy the maintained conditions for release to the next stage of treatment.

b. In ore dressing, oversize material returned to a ball mill for further grinding.

circulating medium

Medium in circulation in or outside a separating bath, at or about the specific gravity of that in the separating bath.

circulating pump

a. A pump (usually centrifugal) used to circulate water through the condenser of a steamplant.

b. A pump used to circulate water in a coal washer or ore concentration plant. c. A pump used to circulate mud or water through a drilling column. Also called slush pump. Syn: mud pump.

circulating scrap

Scrap arising at steelworks and foundries during the manufacture of finished iron and steel or of castings; consists of the sheared-off ends of rolled and other worked products, rejected material, etc. See also: capital scrap.

circulating water

The water in the water circuit of a preparation plant.


a. The passing of any liquid or gas from the surface to the end of the drill string and back to the surface in the process of drilling a borehole.

b. The movement of air currents through mine openings. c. In rotary drilling, the process of pumping mud-laden or other fluid down the drill pipe, through the drilling bit, and upward to the surface through the annulus between the drill-hole walls and the drill pipe.

circulation fluid

The fluid pumped through and to the end of the drill string and back to the surface in the process of drilling a borehole. CF: drilling mud.

circulation loss

The result of drilling or circulation fluid escaping into one or more formations by way of crevices or porous media.

circulation medium

See: circulating medium.

circulation of air

The controlled flow of air to and from the faces to secure adequate ventilation of all workings and traveling roads. See also: dadding.

circulation velocity

The speed, generally expressed in lineal feet per second, at which a fluid or gas travels upward in a borehole after passing the face of the bit.

circulation volume

The amount of liquid or gas circulated through the drill-string equipment in drilling a borehole. The amount of liquid circulated is expressed in gallons (or liters) per minute, and the amount of a gas, as air, is expressed in cubic feet (or cubic meters) per minute.


A surveyor's compass with diametral projecting arms each carrying a vertical slit sight.


a. A settling tank for liquid slag, pulp, etc.

b. An artificial reservoir or tank for holding water.


Issued by regulatory representatives alleging a specific condition or practice that violates mining, maritime, construction, environmental, or general industry standards.


Not the true topaz of mineralogists, but a yellow variety of quartz, which closely resembles topaz in color though not in other physical characters; it is of much less value than true topaz. Known under a variety of geographical names such as Bohemian topaz, Indian topaz, Madagascar topaz, Madeira topaz, and Spanish topaz. Brazilian topaz is the true mineral. Also called quartz topaz. See also: Scotch topaz; false topaz; smoky quartz.

C-J detonation

A detonation characterized by the equivalence of the detonation velocity to the velocity of sound in the burned gas plus the velocity of flow of the burned gases.

C-J plane

See: Chapman-Jouget plane.


a. A valve part. The hinged, lidlike part of a check, clack, or pump valve. Also called check; flap. See also: flapper.

b. A clack or pump valve.

clack seat

The rim or seat on which the hinged lid or flapper of a clack valve closes.

clack valve

A valve having a lidlike piece hinged on one side within a chamber that permits the flow of a fluid or gas to proceed in one direction only. Usually, the check valve on the pickup end of a drill-pump suction hose is a clack-type valve. Also called chock valve; flap valve; flapper valve; foot valve.

clad metal

A composite metal containing two or three layers that have been bonded together. The bonding may have been accomplished by corolling, welding, casting, heavy chemical deposition, or heavy electroplating.


a. Newc. Adhesive. When coal is tightly joined to the roof, the mine is said to have a claggy top. Also spelled cladgy.

b. Newc. Muddy or clayey dirt.


a. The portion of mining ground held under the Federal and local laws by one claimant or association, by virtue of one location and record. Lode claims, maximum size 600 ft by 1,500 ft (182.9 m by 457.3 m). Placer claims 600 ft by 1,320 ft (182.9 m by 402.4 m). A claim is sometimes called a location. See also: title; mining claim.

b. S. Afr. Land on a mining field to which a miner is legally entitled. A Transvaal claim has an area of 64,025 ft (super 2) (5,947.9 m (super 2) or 60,000 Cape square feet). It is about 155 ft (47.3 m) along the strike of the reef, and 413 ft (125.9 m) across the line, or along the dip of the reef. An area of 1.44 claims is equal to a South African morgen. In Cape feet, the claim is 150 ft by 400 ft (46.2 m by 122.0 m). Mining maps are often designed in squares of 1,000 Cape feet by 1,000 Cape feet (304.9 m by 304.9 m), which, therefore, contain about 16 claims measured horizontally. c. In Australia, a claim is defined as the portion of Crown land that any person or number of persons shall lawfully have taken possession of and be entitled to occupy for mining purposes. No land comprised in any mining lease can be considered to be a claim. A claim is marked out by fixing in the ground posts at each angle of the claim, and it need not be surveyed. A miner is required to hold a miner's right before legally marking out or working a claim.


In the Federal mining law, means locator.

claim jumping

The location of a mining claim on supposedly excess ground within the staked boundaries of an existing location on the theory that the law governing the manner of making the original location has not been complied with.

claims held in common

The phrase "held in common" means a claim whereof there are more owners of a claim than one; the use of the words "claims held in common," on which work done upon one of such claims shall be sufficient, means that there must be more than one claim so held, to make a case where work upon one of them shall answer the statutory requirements as to all of them.

claim system

A system used mainly in the United States that grew up in the early days of mining in the Western United States following the gold rush of 1849, as an outgrowth of the desire of a prospector to develop a mineral deposit discovered on the public lands and to have the claim confirmed by law. The mining laws of the United States are based on this system, whereas most other mining countries follow the concession system. CF: concession system.


a. A clip; a haulage clip; an appliance for attaching mine cars to a rope. See also: clip.

b. A clamshell bucket. c. To mud-in the door of a kiln.


Entrance to an oven.


A twin-jawed bucket without teeth; usually hung from the boom of a crane that can be either crawler or wheel mounted. The bucket is dropped in the open position onto the material to be excavated or handled. It is then closed, encompassing material between the two hinged halves.

clamshell loader

A grab-type loader activated by cables. Used in mucking operations.


A compositional category for classifying igneous rocks; e.g., the rhyolite-granite clan. A clan may be defined either by mineralogical or by chemical composition. Clans are subdivided into families.


In inclined shaft timbering, a joint in which the end pieces are checked into the cap and sill for a distance of approx. 1 in (2.5 cm), with a bevel on the inner side.


The wave pattern established when waves are reflected by a barrier so that the crests and troughs occur alternately in the same places with water particle motion limited to vertical movement, while a quarter wavelength away the particle motion is horizontal (back and forth). This is a standing wave phenomenon.


A coal lithotype characterized macroscopically by semibright, silky luster and sheetlike, irregular fracture. It is distinguished from vitrain by containing fine intercalations of a duller lithotype, durain. Its characteristic microlithotype is clarite. CF: clarite; fusain; vitrain.


a. The cleaning of dirty or turbid liquids by the removal of suspended and colloidal matter. See also: recirculation of water.

b. The concentration and removal of solids from circulating water to reduce the suspended solids to a minimum.


A centrifuge, settling tank, or other device for separating suspended solid matter from a liquid.

clarifying tank

A tank for clarifying cyanide or other solutions; frequently provided with a filtering layer of sand, cotton waste, matting, etc.


a. The major maceral or micropetrological constituent of clarain. It is a heterogeneous material that is generally translucent in thin section, and in which there may be intercalated lenticels of such other ingredients, such as xylinite, fusinite, resinite, suberinite, periblinite, collinite, and ulminite.

b. Strictly, not a maceral, but may be used for repetitive description.


A coal microlithotype that contains a combination of vitrinite and exinite totalling at least 95%. The proportions of these two macerals may vary widely, but each must be greater than the proportion of inertinite, and neither must exceed 95%. Distinction may be made between spore clarite, cuticular clarite, and resinous clarite. Clarite is widely distributed and very common, particularly in clarain-type coals and occurs in fairly thick bands. CF: clarain.


The average abundance of an element in the crust of the Earth. CF: clarke of concentration. Syn: crustal abundance.


A mineral, (Na,Ca,Pb) (sub 2) U (sub 2) (O,OH) (sub 7) ; strongly radioactive; metamict; massive; dense; forms as an alteration product of uraninite. Syn: brown gummite.

clarke of concentration

The concentration of an element in a mineral or rock relative to its crustal abundance. The term is applied to specific as well as average occurrences. CF: clarke.

Clark riffler

A sample-reducing device that splits a batch sample of ground ore into two equal streams as it falls across an assembly of deflecting chutes.


A rock-type coal consisting of the maceral vitrinite (tellenite or collinite) and large quantities of other macerals, mainly micrinite and exinite. Micrinite and exinite are present in larger quantities than vitrinite. Syn: clarodurite. CF: duroclarain.


The term clarodurain was introduced by G.H. Cady in 1942, and in the modified form, clarodurite was adopted by the Nomenclature Subcommittee of the International Committee for Coal Petrology in 1956 to designate the microlithotype with maceral composition between that of clarite and durite, but closer to durite than to clarite. It occurs in fairly thick bands; is widely distributed; and, like duroclarite, is a common constituent of most humic coal. Syn: clarodurain.


A rock-type coal consisting of the macerals fusinite and vitrinite and may contain all other macerals. Fusinite is present in a larger quantity than in fusoclarain. CF: fusoclarain.


A rock-type coal consisting of the maceral vitrinite (collinite or telinite) with smaller amounts of other macerals. CF: vitroclarain.


See: clastic rock.


A division of igneous rocks based on the relative proportions of the salic (siliceous and aluminous minerals, quartz, feldspars, and feldspathoids) and femic (ferromagnesian minerals, pyroxene, amphibole, etc.) standard normative minerals as calculated from chemical analyses.

Class 1.1 explosive

Explosive that has a mass explosion hazard or one that will affect almost the entire load instantaneously; previously designated by the U.S. Department of Transportation as a Class A explosive and including, but not limited to, dynamite, nitroglycerin, lead azide, blasting caps and detonating primers.

Class 1.2 explosive

Explosive that has a projection hazard but not a mass explosion hazard; previously designated by the U.S. Department of Transportation as a Class A or B explosive.

Class 1.3 explosive

Explosive that has a fire hazard and either a minor blast hazard or a minor projection hazard or both, but not a mass explosion hazard; previously designated by the U.S. Department of Transportation as a Class B explosive and defined as possessing a flammable hazard, such as, but not limited to, propellant explosives, photographic flash powders, and some special fireworks.

Class 1.4 explosive

Explosive that presents a minor explosive hazard, and explosive effects are confined to the package; no projection of fragments of appreciable size or range is to be expected. An external fire must not cause virtually an instantaneous explosion of almost the entire contents of the package; previously designated by the U.S. Department of Transportation as a Class C explosive and defined as containing Class A or Class B explosives, or both, as components but in restricted quantities.

Class 1.5 explosive

Very insensitive explosive that has a mass explosive hazard but is so insensitive that there is very little probability of initiation or of transition from burning to detonating under normal conditions of transport; large quantities, however, have a higher probability of detonation subsequent to burning; previously designated by the U.S. Department of Transportation as a blasting agent.

Class 5.1 substance

A material that yields oxygen and causes or enhances the combustion of other materials; previously designated by the U.S. Department of Transportation as an oxidizer.

classical washout

A belt of barren ground or thin coal produced by the erosion of a seam by rivers that flowed during or soon after the deposition of the coal. These erosion channels are now filled with sandy sediment. See also: rock roll.


a. The process of separating particles of various sizes, densities, and shapes by allowing them to settle in a fluid.

b. Grading of particles too small to be screened in accordance with their size, shape, and density by control of their settling rate through a fluid medium (water, slurry, or air). c. The evaluation and segregation of trimmed sheet mica according to grades and qualities. d. In powder metallurgy, separation of a powder into fractions according to particle size.

classification of crystals

Of 32 crystal classes (based on 32 point groups, the possible combinations of symmetry elements intersecting at a point) assigned to 7 crystal systems, only 11 are found in common minerals. Each system may be described in terms of three noncoplanar vectors (crystallographic axes) that are generally nonorthogonal as well. Although mineral assignment to a crystal system may require only examination of external crystal morphology, assignment of crystal class commonly requires X-ray diffraction analysis. The crystal systems are triclinic, monoclinic, orthorhombic, tetragonal, trigonal, hexagonal, and isometric. See also: crystallographic axes; crystal systems.

classification of minerals

Each mineral species is a unique, naturally occurring combination of chemical composition and crystal system; e.g., graphite is hexagonal carbon and diamond is isometric carbon, and halite is isometric sodium chloride. (a) Thus, minerals may be classified according to their crystal system. (b) Minerals may be classified chemically according to Dana as (1) native elements and alloys; (2) sulfides, selenides, tellurides, arsenides, and antimonides; (3) sulfosalts, sulfarsenides, sulfantimonides, and sulfobismuthides; (4) halides; (5) oxides; (6) oxygen salts, carbonates, silicates, borates, etc.; (7) salts of organic acids; and (8) hydrocarbon compounds. Silicates are subdivided according to the structural arrangements of their (SiO (sub 4) ) (super 4-) tetrahedral groups and the number of corner oxygen ions shared between them (degree of polymerism). (c) Additionally, minerals may be classified into isostructural groups; e.g., spinel group, garnet group, mica group, pyroxene group, and zeolite group. (Structural classification is not entirely congruent with chemical classification, since some structural groups may contain more than one chemical group; e.g., the apatite group has mainly phosphates, but some arsenates, vanadates, and silicates have the apatite structure.) (d) Rutley classifies minerals according to group in accordance with the periodic table as regards dominant economic constituents. (e) Optically, minerals are classified as opaque (metallic luster) and nonopaque (transmit light in thin section). (f) Economically, minerals are classified as metallics if they are the source of metal from ores and nonmetallics if their products are not metals. See also: classification of crystals.

classified sand fill

Mechanically separated sand or the sand portion of mill tails used as backfill in underground openings. Usually conveyed hydraulically. Also spelled classified sandfill. See also: backfill; sand fill; classifier.


a. A machine or device for separating the constituents of a material according to relative sizes and densities, thus facilitating concentration and treatment. Classifiers may be hydraulic or surface-current box classifiers (spitzkasten).

b. The term classifier is used in particular where an upward current of water is used to remove fine particles from coarser material. See also: centrifugal separation. c. In mineral beneficiation, the classifier is a device that takes the ball-mill discharge and separates it into two portions--the finished product, which is ground as fine as desired, and oversize material. See also: undersize.

classifier dredge

A dredge in which the gravel goes from the trommel to a classifier and then to jigs.


Sorting ore according to its quality.


Consisting of fragments of minerals, rocks, or organic structures that have been moved individually from their places of origin. Syn: detrital; fragmental.

clastic deformation

A process of metamorphism that involves the fracture, rupture, and rolling out of rock and mineral particles. In some instances, the crystal structure may be preserved, but the orientation of the fragments becomes confused. In other instances, the rock may be thoroughly pulverized.

clastic dike

A tabular body of clastic material transecting the bedding of a sedimentary formation, representing extraneous material that has invaded the containing formation along a crack, either from below or from above. See also: sandstone dike; pebble dike.

clastic rock

A consolidated sedimentary rock composed principally of broken fragments that are derived from preexisting rocks (of any origin) or from the solid products formed during chemical weathering of such rocks, and that have been transported mechanically to their places of deposition; e.g., a sandstone, conglomerate, or shale; or a limestone consisting of particles derived from a preexisting limestone. Syn: fragmental rock; clasolite.


A texture found chiefly in leucite rocks, in which the leucite crystals are surrounded by tangential augite crystals in such a way as to suggest a net or a section of a sponge, the felted mass of augite prismoids representing the threads or walls, and the clear, round leucite crystals, the holes.


A monoclinic mineral, As (sub 2) O (sub 3) ; dimorphous with arsenolite.


a. Eng. A tool for cleaning blast holes. Also called clanger.

b. Derb. A piece of stone that has a joint in back of it, which becomes loose and falls when a tunnel has been driven past it.


An isometric mineral, PbSe ; forms a crystal-solution series with galena, which it resembles. Syn: lead selenide.


An extremely fine-grained natural earthy material composed primarily of hydrous aluminum silicates. It may be a mixture of clay minerals and small amounts of nonclay materials or it may be predominantly one clay mineral. The type is determined by the predominant clay mineral. Clay is plastic when sufficiently pulverized and wetted, rigid when dry, and vitreous when fired to a sufficiently high temperature. See also: clay mineral; fireclay; bentonite.

clay back

A back slip in a coal seam containing a clayey deposit. See also: back slip.

clay band

A light-colored, argillaceous layer in clay ironstone. Also spelled clayband.

clay barrel

See: triple-tube core barrel.

clay bit

A mud auger; a mud bit; also, a bit designed for use on a clay barrel. See also: clay-boring bit.

clay book tile

Structural clay tile with tongue and groove edges resembling a book in shape.

clay-boring bit

A special coring bit used to split inner-tube core barrels. The thickness of the bit face is reduced and the inside shoulder is not inset with diamonds to allow a sharp-edged inner barrel to extend through and project a short distance beyond the face of the bit. Also called clay bit; mud bit.

clay course

A clay seam or clay gouge found along the sides of some veins.


Weathered argillaceous material forming a layer immediately overlying bedrock.

clay cutter

Cutting ring at the entry to a pipe feeding into a suction cutter dredge. Set of cutting blades in dredge trommel used to break clay brought up by dredge buckets.

clay dauber

One who seals kiln doors before burning and kiln fireboxes after burning and assists other workers in knocking out doors and in unsealing fireboxes after cooling. Also called dauber; plaster man.


See: argillaceous.

clayey soil

A soil in which clay is the basic constituent. The clay contributes to strength by cohesion, but detracts from stability by volume change and by plastic flow under load.

clay gall

a. Mud curl or cylinder formed by drying and cracking of thin layers of coherent mud; commonly rolled or blown into sand and buried; flattened upon wetting forming a lenticular bleb of clay or shale.

b. Eng. Clay gall pellet of clay or mudstone, often ocherous, sometimes hollow, found esp. in false-bedded oolitic limestones such as forest marble.

clay gouge

a. A clayey deposit in a fault zone. See also: fault gouge.

b. A thin seam of clay separating masses of ore, or separating ore from country rock. See also: gouge.

clay gun

Equipment used to fire a ball of fire clay into the tap hole of a blast furnace. See also: mud gun.

clay hole

See: clay pocket.


Lining a borehole with clay, to keep explosives dry.

claying bar

A rod or tool for lining a newly made coal shot hole with clay to seal up any breaks in the walls of the hole. The hole is filled with clay to about one-third of its length. The claying bar is driven in by hammer to the limit and rotated by a tommy bar in the eyelet at the outer end of the bar. See also: clay iron; bull; scraper and break detector.

clay iron

An iron rod used for ramming clay into wet drill holes. See also: bull; claying bar.

clay ironstone

a. A compact hard, dark, gray or brown, fine-grained sedimentary rock consisting of a mixture of argillaceous material (up to 30%) and iron carbonate (siderite), occurring in layers of nodules or concretions or as relatively continuous irregular thin beds, and usually associated with carbonaceous strata, esp. overlying a coal seam in the coal measures of the United States or Great Britain; a clayey iron carbonate, or an impure siderite ore occurring admixed with clays. The term has also been applied to an argillaceous rock containing iron oxide (such as hematite or limonite). See also: blackband ironstone.

b. A sideritic concretion or nodule occurring in clay ironstone and other argillaceous rocks, often displaying septarian structure. c. See: ironstone; iron clay.

clay loam

a. A fine-textured soil that breaks into clods or lumps that are hard when dry. When the moist soil is pinched between the thumb and finger, it will form a thin ribbon that will break readily, barely sustaining its own weight. The moist soil is plastic and will form a cast that will bear much handling. When kneaded in the hand, it does not crumble readily but tends to work into a heavy compact mass.

b. A soil containing 27% to 40% clay, 20% to 45% sand, and the remainder silt.

clay maker

One who blends and mixes various clays, as shipped from a mine, into a thin, semiliquid form by operating a blunger (mixing machine). Also called blunger machine operator; clay mixer; clay washer; slip maker; slip mixer; wet mixer.

clay marl

A chalky clay, or a marl in which clay largely predominates.

clay mineral

a. A colloidal-size, crystalline, hydroxyl silicate having a crystal structure of the two-layer (7 Aa) type (kaolinite), or of the three-layer (14 Aa) type (smectite), in which layers of silicon and aluminum ions have tetrahedral coordination with respect to oxygen, while layers of aluminum, ferrous and ferric iron, magnesium, chromium, lithium, manganese, and other cations have octahedral coordination with respect to oxygen and to hydroxyl ions. Exchangeable cations may attach to the silicate layers in an amount determined by the excess negative charge within the composite layers. These cations commonly are calcium and sodium, but may also be potassium, magnesium, hydronium, aluminum, or others. The most common clay minerals belong to the kaolinite, smectite, attapulgite, and illite (hydromica) groups. Mixed-layer clay minerals are either randomly or regularly interstratified intergrowths of two or more clay minerals. See also: clay.

b. Any mineral found in the clay fraction (less than 4 mu m) of a soil or sediment; e.g., rock flour comminuted by glacial grinding. c. Any kandite mineral of the kaolinite-serpentine group.


a. A playa formed by deflation of alluvial topsoils in a desert, in which water collects after a rain.

b. A term used in Australia for a shallow depression containing clayey and silty sediment, and having a hard, sun-baked surface. c. See: hardpan.

clay parting

a. Clayey material bound between a vein and its wall. Also called casing; parting.

b. Seams of hardened carbonaceous clay between or in beds of coal.


a. A sump in which a drilling mud is mixed and stored.

b. A pit or sump in which the return fluid from a borehole is collected and stored for recirculation. c. A pit where clay is dug.

clay pocket

A clay-filled cavity in rock; a mass of clay in rock or gravel. Syn: clay hole.

clay rock

See: claystone.

clay sapropel

Clay deposit containing sapropel.

clay shale

a. A consolidated sediment consisting of no more than 10% sand and having a silt to clay ratio of less than 1:2 (Folk, 1954, p. 350); a fissile claystone.

b. A shale that consists chiefly of clayey material and that becomes clay on weathering.

clay size

Said of that portion of soil or sediment that is finer than 2 to 5 mu m.

clay slate

a. A low-grade, essentially unreconstituted slate, as distinguished from the more micaceous varieties that border on phyllite.

b. A slate derived from an argillaceous rock, such as shale, rather than from volcanic ash; a metamorphosed clay, with cleavage developed by shearing or pressure, as distinguished from mica slate.

clay stains

Yellowish-brown or rust-colored films from deposits of clay minerals.


a. A term applicable to indurated clay in the same sense as sandstone is applicable to indurated or cemented sand. Syn: clay rock. See also: mudstone; siltstone.

b. One of the concretionary masses of clay frequently found in alluvial deposits, in the form of flat rounded disks either simple or variously united so as to give rise to curious shapes.

clay temperer

See: wet-pan operator.

clay vein

A body of clay, usually roughly tabular in form like an ore vein, that fills a crevice in a coal seam. It is believed to have originated where the pressure was high enough to force clay from the roof or floor into small fissures and in many instances, to alter and to enlarge them. Also called horseback.

clay wash

a. A deposit of clay transported and deposited by water.

b. The agitation of an oil with fuller's earth or some other clay to improve the color or odor of the oil. c. A thin emulsion of clay and water, sometimes used to strengthen the face of a mold. d. Clay thinned with water and used for coating gaggers and flasks.

clay washer

See: clay maker.


a. Free from combustible gases or other noxious gases.

b. A coal seam free from dirt partings. c. A diamond or other gem stone free from interior flaws. d. A borehole free of cave or other obstructing material. e. A mineral virtually free of undesirable nonore or waste rock material. f. Free of foreign material. In reference to sand or gravel, it means lack of binder

Clean Air Act

U.S. law: 42 USC Sections 7401-7428 (1979) and resulting regulations in 40 CFR51, administered by USEPA. Its objective is to reduce atmospheric pollution to acceptable limits. Inter alia, it empowers local authorities to declare smoke control areas in which the emission of any smoke from chimneys will constitute an offense. The act became part of Great Britain's national legislation in July 1956, although its main provisions did not become effective until June 1, 1958. See also: coal smoke; smoke.

clean cutting

A rock formation, the cuttings of which do not tend to mud up on the face of a diamond or other bit.

clean cuttings

a. Rock cuttings that do not ball or adhere to the walls of a borehole.

b. Rock cuttings not contaminated by cave material or drill-mud ingredients.

cleaned coal

Coal produced by a mechanical cleaning process (wet or dry).


Scot. A scraper for cleaning out a shothole.

cleaner cell

Secondary cell for the retreatment of the concentrate from a primary cell.#WORD �9� �22� recleaner cell �5362� �5363� Syn: recleaner cell.

clean hole

A borehole free of cave or other obstructing material.


a. A general term for the methods and processes of separating dirt from coal or gangue from mineral. See also: coal-preparation plant; roughing.

b. The retreatment of the rough flotation concentrate to improve its quality.

cleaning plant

See: coal washer; preparation plant.


a. To remove cave or other obstructing material from a borehole.

b. A port or opening provided in the body or base of a machine or other mechanism through which accumulated debris may be removed.

cleanout auger

See: cleanout jet auger.

cleanout jet auger

An auger equipped with water-jet orifices designed to clean out collected material inside a driven pipe or casing before taking soil samples from strata below the bottom of the casing. Also called cleanout auger; M.P.F.M. jet auger.


a. The operation of collecting all the valuable product of a given period of operation in a stamp mill, or in a hydraulic or placer mine.

b. The valuable material resulting from a cleanup. c. To load all the coal a miner has broken. d. The cleanup of sluices in placer mining is a similar process that occurs daily or more often. The gold, tin, or other concentrate is shoveled out for further treatment. e. To police and tidy up a drill rig and the surrounding area.

cleanup barrel

A barrel used to batch grind and then amalgamate gold-bearing concentrates and residues.


a. Translucent diamond with few visible spots or flaws.

b. Water that has not been recirculated in drilling and hence is free of drill cuttings and sludge. Also applied to return water when it contains little or no entrained cuttings or sludge. c. A safe working place. d. Transparent, such as in clear quartz, clear glass.


a. The space between the top or side of a car and the mine roof or wall.

b. Technically, the annular space between downhole drill-string equipment, such as bits, core barrels, casing, etc., and the walls of the borehole with the downhole equipment centered in the hole. Loosely, the term is commonly and incorrectly used as a syn. for exposure. See also: exposure; inside clearance. c. The amount of open space around a drill or piece of mining equipment in an underground workplace.

clearance space

A space in pumps of the piston and ram types, usually quite small, between the cylinder end and the piston at the end of its stroke. The height to which water can be raised on the suction side is influenced by the volume of this space.

clear clay

A clay such as kaolin that is free from organic matter and so does not give rise to bubbles if used in a vitreous enamel; such clays are used in enamels when good gloss and clear colors are required.


A reservoir (in saltmaking) into which brine is conveyed.


The removal of all standing growth, whether bushes or trees.

clearing and grubbing

Removal of tree stumps before excavation starts on a construction site.

clearing hole

A hole drilled to a slightly larger diameter than the bolt passing through it. The clearance for black bolts is normally 1/16 in (1.6 mm).

clear mica

Transparent muscovite without stains and with a smooth surface in reflected light.

clear span

The clear unobstructed distance between the inner extremities of the two supports of a beam. This dimension is always less than the effective span. See also: effective span.


a. Term applied to systems of joints, cleavage planes, or planes of weakness found in coal seams along which the coal fractures. See also: facing; face cleat; bord; butt cleat. Also spelled cleet.

b. Main joint in a coal seam along which it breaks most easily. Runs in two directions, along and across the seam. c. Joints in coal more or less normal to the bedding planes. d. An attachment fastened to a conveying medium to help propel material along the path of travel.

cleat spar

York. Crystalline mineral matter, often ankerite, occurring in the cleat cracks of coal.


a. The breaking of a mineral along its crystallographic planes, thus reflecting crystal structure. CF: parting.

b. The property or tendency of a rock to split along secondary, aligned fractures or other closely spaced planes or textures, produced by deformation or metamorphism. c. In quarrying, the cleavage of rocks is often called the rift.

cleavage banding

A compositional banding that is parallel to the cleavage rather than to the bedding. It results from the mechanical movement of incompetent material, such as argillaceous rocks, into the cleavage planes in a more competent rock, such as sandstone. Ordinarily, the argillaceous bands are only a few millimeters thick. See also: segregation banding.

cleavage plane

The plane along which cleavage takes place.


As used by the diamond-cutting and diamond-bit-setting industries, the more or less flat diamond fragments produced by splitting a crystalline diamond along the octahedral plane. Such fragments are used primarily as a material from which special-shaped, diamond-pointed cutting tools are produced. See also: melee.


To split a crystalline substance, such as a diamond, along a cleavage plane.


A white, lamellar, or leaflike variety of albite, having an almost pure Ab content and commonly forming fan-shaped aggregates of tabular crystals that show mosaic development and appear as though bent; formed as a late-stage mineral in pegmatites, replacing other minerals. Also spelled clevelandite.


Splitting a crystal along a cleavage plane.

cleaving way

Corn. A direction parallel to the bedding planes of a rock. CF: roughway; quartering way.


a. Scot. To load cages at the shaft bottom or at midworkings.

b. Scot. See: haulage clip.


An abrupt chasm, cut, breach, or other sharp opening, such as a craggy fissure in a rock, a wave-cut gully in a cliff, a trench on the ocean bottom, a notch in the rim of a volcanic crater, or a narrow recess in a cave floor. Obsolete syn: clift.

Clerici solution

A molecular mixture of thallium malonate and thallium formate. Used as a heavy solution for the separation of minerals. The solution has a maximum density of 4.25 g/cm (super 3) at 20 degrees C. It is prepared by adding formic acid to one of two equal quantities of thallium carbonate, and adding malonic acid to the other until each is neutralized. The two solutions are then mixed, filtered, and evaporated until almandite floats. CF: Sonstadt solution; Klein solution; bromoform; methylene iodide.


A variety of uraninite containing a large percentage of UO (sub 3) ; also rich in helium. Contains about 10% of the yttrium earths.


a. In coal mining, a spring hook or snap hook used to attach the hoisting rope to the bucket. Also called clivvy.

b. A U-shaped iron hook used with an iron pin for connecting ropes to the drawbars of cars or, when used with iron links, for coupling cars together. Also used as a connecting link between chains or lines or to hang a sheave in a drill tripod or derrick.