Appendix:Dictionary of Mining, Mineral, and Related Terms/B/3

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See: bearers.


Eng. A timber stay or beam in a shaft. See also: bearer. Also spelled byat.


The optical character of crystals belonging to the orthorhombic, monoclinic, and triclinic systems, which exhibit double refraction, but have two directions of single refraction and isotropy, i.e., two optic axes. CF: uniaxial.

biaxial stone

A mineral that has crystallized in the orthorhombic, monoclinic, or triclinic system and hence has two optic axes. CF: uniaxial stone.


An aerial ropeway using stationary track ropes along which carriers are hauled by an endless haulage rope. See also: aerial ropeway.

bicylindroconical drum

A winding drum with a cylindrical middle portion and two conical outer portions; used sometimes where the weight of the winding rope is large compared with the coal or mineral load. The heavily loaded upgoing rope winds on the small diameter, while the downgoing rope winds off the large diameter. The effect is to compensate for the heavy torques due to rope unbalance and acceleration. See also: cylindroconical drum; winding drum.


A monoclinic mineral, CoSO (sub 4) .7H (sub 2) O ; melanterite group; flesh-red to rose-red; esp. in crusts and stalactites. Syn: cobalt vitriol.

bifurcating feeder

One that separates objects moving in a single lane and delivers them to two lanes of movement.

Big Coal D

Nongelatinous permissible explosive; used in coal mining.


N. of Eng. A built-up pillar of stone or other debris in a working place or heading to support the roof; e.g., "bigging the gob" means building a pack in a worked-out place.

big-stone bit

Bits set with diamonds as large or larger than eight stones per carat in size.


A monoclinic and triclinic mineral, LiAlSi (sub 2) O (sub 6) .H (sub 2) O; may be in zeolite group; colorless or white; in granular aggregates with eucryptite in lithia pegmatites.

bilateral transducer

A transducer capable of transmission in either direction between its terminations. Syn: reversible transducer.

Bilharz table

A side-bump table having a surface made of a plane, endless, traveling belt. The Corning, Luhrig, and Stein tables are similar.


A monoclinic mineral, Fe (super 2+) Fe (super 3+) (sub 2) (SO (sub 4) ) (sub 4) .22H (sub 2) O ; hallotrichite group; white to yellowish; in radially fibrous masses.


Aust. A name used in the Clermont district of Queensland for a bed of quartzite that caps the coal measures.

billy coal

Staff. Miners' term for a thin, unworkable coal seam occurring above or below a workable seam.


Generic term for porphyritic rocks in which the minerals occur in two generations.


A container for storing material.

binary alloy

An alloy containing two component elements.

binary cycle

A cycle in which two different media are employed, one superimposed on and augmenting the cycle of the other.

binary explosive

An explosive based on two ingredients, such as nitromethane and ammonium nitrate, which are shipped and stored separately and mixed at the blast site to form an explosive mixture.

binary granite

Two-mica granite.

binary system

A chemical system containing two components, e.g., the MgO-SiO (sub 2) system.


a. Shale or mudstone occurring in coal measures. Obsolete.

b. To prevent normal operation of drill-string equipment in a borehole, such as by constriction or friction created by swelling or caving ground, settlement or balling of cuttings, an obstruction, or an offset or crooked hole, or as the result of insufficient clearance cut by use of undergage bits or reaming shells. c. To cause to cohere; to give consistency to by means of an agent, such as by drilling mud in a loose, sandy, or fragmented formation. d. A British coal miner's term for any fine-grained, well-laminated rock (such as shale, clay, or mudstone, but not sandstone) associated with coal. See also: blaes.


a. A substance used to produce cohesion in loose aggregate, as the crushed stones in a macadam road.

b. A material added to coal or iron ore during the process of briquetting or pelletizing to facilitate adhesion between the particles. c. Corn. Beds of grit in shale, slate, or clay. d. Streak of impurity in a coal seam, usually difficult to remove. e. The material that produces or promotes consolidation in loosely aggregated sediments; e.g., a mineral cement that is precipitated in the pore spaces between grains and that holds them together, or a primary clay matrix that fills the interstices between grains. f. Soil binder. g. A term used in Ireland for a bed of sand in shale, slate, or clay. h. A coal miner's term used in Pembrokeshire, England, for shale.

binderless briquetting

The briquetting of coal by the application of pressure without the addition of a binder.


An isometric mineral, Pb (sub 2) Sb (sub 2) O (sub 6) (O,OH) ; stibiconite group; yellow to reddish-brown; in the oxidation zone of lead-antimony ore deposits.

binding bolt

See: anchor bolt.

bin feeder

A worker who rods or bars ore that sticks as it passes through the bin door.


To put coal in wagons or in stacks at the surface.

bin gate

A device for complete shutoff or control of gravity-impelled flow of materials from a bin, bunker, hopper, or other container. Syn: bucket gate; bunker gate. See also: regulating gate.

Bingham model

One of many rheological models of material behavior. Rheology is the study of change in form and the flow of matter, embracing elasticity, viscosity, and plasticity. A Bingham material is elastic until the yield point is reached; flow occurs beyond the yield point.

bing hole

Derb. A hole or chute through which ore is thrown.

bing ore

The purest lead ore and with the largest crystals of galena.

bing place

Derb. The place where ore is stored for smelting.


A silver-bearing variety of tennantite.


A determination of the concentration of a substance in biological fluids and tissue by analysis of urine, feces, blood, bone, tissue, etc.

biochemical deposit

A precipitated deposit resulting directly or indirectly from vital activities of an organism, such as bacterial iron ore or coralline limestone.

biochemical prospecting

a. See: biogeochemical prospecting.

b. Prospecting by means of vegetation. The root systems of trees are actually powerful sampling mechanisms that represent samples of solutions from a large volume of earth. Much of the mineral content from these solutions is found in the leaves. Analysis of leaves may serve as a guide to prospectors.


Said of rocks consisting of fragmental organic remains.


Said of a rock resulting from the physiological activities of organisms, e.g., a coral reef.

biogeochemical anomaly

An area where the vegetation contains an abnormally high concentration of metals.

biogeochemical prospecting

Geochemical exploration based on the chemical analysis of systematically sampled plants in a region, to detect biological concentrations of elements that might reflect hidden orebodies. The trace-element content of one or more plant organs is most often measured. Syn: biochemical prospecting. CF: geobotanical prospecting.


A branch of geochemistry that deals with the effects of life processes on the distribution and fixation of chemical elements in the biosphere.


A moundlike or circumscribed mass of rock built up by sedentary organisms such as corals, mollusks, and algae. CF: biostrome. Syn: reef knoll.


The catalytic action of bacteria, such as Thiobacillus ferroxidans and Thiobacillus thiooxidans to accelerate chemical oxidation reactions by as much as 10 (super 6) times those of chemical reactions alone; esp. useful in leaching copper and uranium systems.


a. A group name for minerals formed by biologic action.

b. See: biolith. c. An old term for a concretion formed through the action of living organisms.


A rock of organic origin; a biogenic rock.


The emission of visible light by living organisms.

biomechanical deposit

A deposit due to the detrital accumulation of organic material, as in the cases of limestones and coal.


See: ecology.


See: black shale.


a. An element that is required by or found in the bodies of living organisms. The list of such elements includes carbon, hydrogen, oxygen, nitrogen, phosphorus, sulfur, chlorine, iodine, bromine, calcium, magnesium, potassium, sodium, vanadium, iron, manganese, and copper. All may belong also to the chalcophile or lithophile groups.

b. Said of those elements that are the most typical in organisms and organic material. c. Said of those elements that are concentrated in and by living plants and animals.


A tank equipped for temperature, pH, and reagent control used to employ bacteria to oxidize or reduce ores of gold and other metals and render them amenable for metal extraction by leaching.


a. All the area occupied or favorable for occupation by living organisms. It includes parts of the lithosphere, hydrosphere, and atmosphere.

b. All living organisms of the Earth and its atmosphere.


A bedded, blanketlike mass of rock composed mainly of the remains of sedentary organisms; an organic layer, such as a bed of shells or corals, or even a coal seam. CF: bioherm.


a. A monoclinic mineral, K (sub 2) Mg (sub 6) (Si (sub 6) Al (sub 2) O (sub 20) )(OH,F) (sub 2) ; mica group, with Fe (super 2+) replacing Mg and Fe (super 3+) replacing Al; in masses with perfect basal cleavage; dark brown, dark green, black; a common rock-forming mineral in crystalline rocks, either as an original crystal in igneous rocks or as a metamorphic product in gneisses and schists; a detrital constituent of sedimentary rocks.

b. A general term to designate all ferromagnesian micas. Syn: black mica; dark mica; magnesia mica. See also: iron mica.

biotite gneiss

A gneiss in which biotite is the prominent dark mineral.


A jet black igneous rock consisting essentially of biotite. Near Libby, MT, such a rock has been altered to vermiculite by hot waters.

Biot number

The heat-transfer ratio hr/k, where h is the heat-transfer coefficient, r is the distance from the point or plane under consideration to the surface, and k is the thermal conductivity. The Biot number is a useful criterion in assessing thermal-shock resistance.

bipolar electrode

An electrode that is not mechanically connected to a power supply but is placed in an electrolyte, between the anode and the cathode, such that the part nearer the anode becomes cathodic and the part nearer the cathode becomes anodic. Syn: intermediate electrode.


A closed crystal form consisting of a positive and negative pyramid. CF: pyramid.


A geophysical measuring device such as a magnetometer, plus the housing in which it is towed behind an aircraft.


a. Mixed screened anthracite passing a 1/2-in (12.7-mm) screen, but retained on a 1/8-in (3.2-mm) screen. May be subdivided into buckwheat, rice, and barley. See also: anthracite coal sizes; barley; bird's-eye coal.

b. Eng. Applied to various rocks with small spots, in some places to a concretionary slate, and in Guernsey to a spotted variety of diorite or gabbro.

bird's-eye coal

Sometimes applied to anthracite coal when very small fractures are numerous and freshly broken surfaces display rounded or oval eyelike forms, many of which have convex surfaces. See also: anthracite coal sizes; bird's-eye.

bird's-eye limestone

A very fine-grained limestone containing spots or tubes of crystalline calcite.

bird's-eye porphyry

A name given by prospectors and miners to a fine-grained igneous rock having small phenocrysts, particularly if they are quartz, from a fancied resemblance to birds' eyes.

bird's-eye slate

A quarryman's term for slate containing abundant deformed or squeezed concretions.

Bird solid-bowl centrifuge

A fine-coal dewatering machine that consists of a tank or truncated conical shell, which is revolved at the desired speed by means of a drive sheave. A screw conveyor rotates inside the cone or bowl at a slightly lower speed in the same direction of rotation. The feed entrance, in the center of the large end of the truncated cone, is high enough to allow formation of a pool of slurry. Adjustable effluent-discharge parts are so located in the large end of the bowl that the level of liquid is maintained at the desired height. The solids are steadily moved forward by the screw conveyor as fast as they are deposited, being carried above the level of the pool for an interval before leaving the bowl. Discharge of both solids and effluent is continuous.


See: birefringent.


See: birefringent.


a. The numerical difference between the refractive indices of a mineral. This difference results in a display of interference colors when thin sections or small fragments of anisotropic minerals are viewed between crossed polars. Isometric minerals and amorphous materials are isotropic and have the same refractive index in every direction; they have no birefringence and show no interference colors. See also: colors.

b. The property of anisotropic crystals to split a beam of light into two polarized rays that traverse the crystal at different velocities as they pass through it and produce characteristic optical effects that are recognizable with the proper instruments or, in some cases (e.g., calcite), by the eye alone. Syn: double refraction. CF: transmitted light.


Said of a crystalline substance that displays birefringence; such materials have more than one index of refraction. Syn: birefractive; birefracting.


See: boule.


A monoclinic mineral, Na (sub 4) Mn (sub 14) O (sub 27) .9H (sub 2) O ; black or dark-brown, named for Birness, Scotland.

Birtley coal picker

An electric picker that distinguishes between good coal and slate by their different electrical conductivities. It is said to be more accurate than the human slate picker, who, when fatigued, may fail to remove all the impure material.

Birtley contraflow separator

A pneumatic table for dry cleaning coal. It consists of perforated deck plates arranged in a series of lateral steps with a longitudinal inclination. A centrifugal fan provides a constant upward blast of air through the deck. The usual layering takes place, the refuse sinking to the deck plates. The capacity of the table ranges from 6 st/h per foot (17.8 t/h/m) of width for sizes 1-1/2 to 2 in (3.8 to 5.1 cm), down to 2 st/h/ft (5.9 t/h/m) for fines below 1/16 in. They are built in any width up to a maximum of about 8 ft (2.4 m).


A monoclinic mineral, MgCl (sub 2) .6H (sub 2) O .


a. Unglazed ceramic ware that has been fired in a biscuit or bisque oven or film.

b. A small cake of primary metal, such as uranium, made from uranium tetrafluoride and magnesium in a bomb reduction.

bishop's stone

See: amethyst.


In metallurgy, a slag with a silicate degree of 2.


A straw-yellow monoclinic mineral, Bi (sub 2) O (sub 3) ; earthy to powdery; in oxidized parts of bismuth ores. Syn: bismuth ocher.


A tetragonal mineral, BiOCl .


A white crystalline, brittle metal with a pinkish tinge. Symbol, Bi. The most important ores are bismuthinite or bismuth glance (Bi (sub 2) S (sub 3) ) and bismite (Bi (sub 2) O (sub 3) ). Also obtained as a byproduct in refining lead, copper, tin, silver, and gold ores. Forms low-melting alloys that are used in fire detection and extinguishing systems; used as a catalyst for making acrylic fibers and as a carrier for fuel in atomic reactors; extensively used in cosmetics and in medicine.

bismuth blende

See: eulytite.

bismuth glance

See: bismuthinite.

bismuth gold

A pinkish-white native alloy of bismuth and gold, approx. Au (sub 2) Bi ; contains 65.5% gold. See: maldonite.


See: bismuthinite.


An orthorhombic mineral, 4[Bi (sub 2) S (sub 3) ] ; metallic; lead-gray to tin-white with an iridescent tarnish; commonly associated with other ore minerals; a source of bismuth. Syn: bismuth glance; bismuthine.

bismuth ocher

See: bismite.

bismuth selenide

Bi (sub 2) Se (sub 3) ; black; orthorhombic; and melting point, 706 degrees C. Of some interest for thermoelectric applications. Also called bismuth triselenide.

bismuth spar

See: bismutite.

bismuth telluride

Bi (sub 2) Te (sub 2) S ; hexagonal rhombohedral; gray; and a thermoelectric material. Because it loses its semiconducting properties above 100 degrees C, it is of value chiefly in cooling devices. Also called bismuth tritelluride. Syn: tetradymite.


A tetragonal mineral, Bi (sub 2) (CO (sub 3) )O (sub 2) ; earthy or amorphous. Syn: bismuth spar.


An orthorhombic mineral, Bi(Ta,Nb)O (sub 4) .


In crystallography, a form apparently consisting of two sphenoids placed together symmetrically. CF: disphenoid.


Any device that may be attached to, or is, an integral part of a drill string and is used as a cutting tool to bore into or penetrate rock or other materials by utilizing power applied to the bit percussively or by rotation. See also: detachable bit; drag bit.

bit blank

A steel bit in which diamonds or other cutting media may be inset by hand peening or attached by a mechanical process such as casting, sintering, or brazing. Syn: bit shank; blank; blank bit; body; shank.

bit clearance

a. Technically, the difference between the outside diameter of a set bit and the outside set diameter of the reaming shell. Loosely, the term is used to denote the clearing action of a bit, which is a function of the waterways and the mode in which the diamonds or other cutting media are set in the cutting face of the bit, and also the difference between the outside set diameter of a bit and the outside diameter of the bit shank.

b. Incorrectly and loosely used as a syn. for diamond exposure. See also: diamond exposure.

bit contour

The configuration of the crown or cutting face of a bit as seen in cross section.

bit core

The central, removable, and replaceable portion or pilot of a noncoring or other type of bit. CF: core.

bit count

See: diamond count.

bit crown

See: crown.

bit-crown metal

See: diamond matrix.

bit die

See: bit mold.

bit disc

A bit with two or more rolling discs that do the cutting. Used in rotary drilling through certain formations.

bit drag

A bit with serrated teeth used in rotary drilling.

bit face

That part of the bit crown that comes in contact with the bottom of a borehole. It does not include that part of the bit crown that contacts the walls of the borehole.

bit feed

See: feed rate.

bit life

The average number of feet of borehole a bit may be expected to drill in a specific type of rock under normal operating or specified conditions.

bit load

The weight or pressure applied to a bit in drilling operations, expressed as the number of pounds or tons of weight applied. Syn: bit pressure; bit weight; drilling pressure; drilling weight; drill pressure; load.

bit matrix

See: diamond matrix.

bit mold

A steel, carbon, or ceramic die in which the shape of a bit crown is incised and provided with pips, grooves, or holes in which diamonds are set and held by suction or an adhesive. Filling the die with a matrix alloy by a casting or a powder metal-sintering process affixes the shank to a diamond-inset bit crown having a shape conforming to that incised in the die. Syn: bit die; crown die; crown mold.

bit performance

The achievement of a bit as gaged by the overall cost of using a specific bit per a unit measure of borehole drilled, or by the total number of feet of borehole drilled per bit.

bit pressure

See: bit load.

bit reaming shell

Obsolete name for reaming shell.

bit ring

a. See: setting ring.

b. Obsolete name for core bit.

bit shank

a. The threaded part of a bit.

b. Sometimes incorrectly used as a syn. for bit blank.

bitter lake

A salt lake whose waters contain in solution a high content of sodium sulfate and lesser amounts of the carbonates and chlorides ordinarily found in salt lakes; a lake whose water has a bitter taste. Examples include Carson Lake, NV, and the Great Bitter Lake in Egypt.


a. The bitter liquid remaining after seawater has been concentrated by evaporation until most of the sodium chloride has crystallized out.

b. A natural solution, in an evaporite basin, that resembles a saltworks liquor, esp. in its high magnesium content.

bitter salt

See: epsomite.

bitter spar

a. A pure, crystalline dolomite that consists of 1 part or equivalent of calcium carbonate and 1 part of magnesium carbonate. Syn: pearl spar.

b. See: dolomite.

bit thrust

The hydraulic pressure applied to a drill bit when drilling, as shown in pounds per square inch by the pressure gages on the hydraulic-feed cylinders of a diamond drill or the total pressure in pounds as calculated by multiplying the recorded hydraulic pressure by the square-inch area of the piston in the hydraulic-feed cylinder. Syn: drilling thrust.


a. A general name for various solid and semisolid hydrocarbons. In 1912, the term was used by the American Society for Testing and Materials to include all those hydrocarbons that are soluble in carbon disulfide, whether gases, easily mobile liquids, viscous liquids, or solids.

b. A generic term applied to natural flammable substances of variable color, hardness, and volatility, composed principally of a mixture of hydrocarbons substantially free from oxygenated bodies. Bitumens are sometimes associated with mineral matter, the nonmineral constituents being fusible and largely soluble in carbon disulfide, yielding water-insoluble sulfonation products. Petroleums, asphalts, natural mineral waxes, and asphaltites are all considered bitumens.

bitumen cable

A cable notable for its resistance to moisture, but not suitable for high temperatures. The wires are tinned to prevent reaction with the sulfur in the bitumen. Outside the bitumen are layers of tape and jute, and one or two layers of steel armoring; outside each layer of steel armoring are layers of serving compound.


Cannel coal from Torbane, Scotland. See also: torbanite. Also spelled bituminite.

bitumen lapideum

An old name for mineral coal.


Yielding or containing bitumen.


High explosive used in mines.


a. Containing bitumen.

b. Pertaining to bituminous coal. c. Having the odor of bitumen; often applied to minerals. d. Yielding volatile bituminous matter on heating (for example, bituminous coal). e. Containing much organic, or at least carbonaceous, matter, mostly in the form of the tarry hydrocarbons, which are usually described as bitumen.

bituminous coal

a. Coal that ranks between subbituminous coal and anthracite and that contains more than 14% volatile matter (on a dry, ash-free basis) and has a calorific value of more than 11,500 Btu/lb (26.7 MJ/kg) (moist, mineral-matter-free) or more than 10,500 Btu/lb (24.4 MJ/kg) if agglomerating (ASTM). It is dark brown to black in color and burns with a smoky flame. Bituminous coal is the most abundant rank of coal; much is Carboniferous in age. CF: medium-volatile bituminous coal; low volatile bituminous coal. Syn: soft coal.

b. A coal that is high in carbonaceous matter, having between 15% and 50% volatile matter. Soft coal. c. A general term descriptive of coal other than anthracite and low-volatile coal on the one hand and lignite on the other. d. A coal with a relatively high proportion of gaseous constituents; dark brown to black in color and burns with a smoky luminous flame. The coke yield ranges from 50% to 90%. The term does not imply that bitumen or mineral pitch is present. See also: coking coal.

bituminous grout

A mixture of bituminous material and fine sand that will flow into place without mechanical manipulation when heated.

bituminous limestone

A dark, dense limestone containing abundant organic matter, believed to have accumulated under stagnant conditions and emitting a fetid odor when freshly broken or vigorously rubbed; e.g., the Bone Spring Limestone of Permian age in west Texas. Syn: stinkstone; anthraconite. See also: swinestone.

bituminous ores

Iron ores in which the gangue consists principally of coaly matter; e.g., black band ironstone.

bituminous rock

Natural or rock asphalt, but the term is sometimes used to describe a rock in which the percentage of impregnation is comparatively low.

bituminous shale

A shale containing bituminous material; coaly shale. CF: oil shale.

bit wall

That portion of the bit between the crown and the shank of the bit.

bit weight

a. Total weight, in carats, of the diamonds set in a diamond bit.

b. Weight or load applied to a diamond bit during a drilling operation. See also: bit load.


A monoclinic mineral, CaLiAl (sub 2) (AlBeSi (sub 2) O (sub 10) )(OH) (sub 2) ; mica group; perfect basal cleavage.


a. Having a valence of 2.

b. Having two valences; e.g., cobalt has two forms, with valences of 2 and 3, respectively.


A red variety of beryl; in the Wah Wah and Topaz Mountains of Utah.


An isometric mineral, (Mn,Fe) (sub 2) O (sub 3) ; forms black cubes. Formerly called partridgeite and sitaparite.

black alkali

An old term for an alkali soil whose sodium tends to disperse organic matter and give a black color. CF: white alkali.

black amber

A name given to jet that is found with amber. It becomes faintly electric when rubbed. See also: jet; stantienite.

black andradite garnet

See: melanite.

black ash

a. Any of various dark-colored products obtained in industrial processes.

b. A black mass containing chiefly soda in the form of sodium carbonate and usually also sodium sulfide with some carbon, and produced esp. for recovery of its soda content by concentrating and burning black liquor in rotary furnaces.


a. A dark, earthy variety of the mineral siderite, occurring mixed with clay, sand, and considerable carbonaceous matter, and frequently associated with coal. Syn: blackband ore.

b. A thin layer (up to 10 cm in thickness) of blackband interbedded with clays or shales in blackband ironstone. c. See: blackband ironstone.

blackband ironstone

A dark variety of clay ironstone containing sufficient carbonaceous matter (10% to 20%) to make it self-calcining (without the addition of extra fuel). Syn: blackband. See also: clay ironstone.

blackband ore

See: blackband.

black bat

A piece of bituminous shale embedded in the rock immediately over the coal measure and liable to fall of its own weight when the coal beneath it has been removed. CF: kettle bottom.

black body

As applied to heat radiation, this term signifies that the surface in question emits radiant energy at each wavelength at the maximum rate possible for the temperature of the surface and, at the same time, absorbs all incident radiation. Only when a surface is a black body can its temperature be measured accurately by means of an optical pyrometer.

black box

A separate and self-contained electronic unit or element of an electronic device which can be treated as a single package.

black chalk

A bluish-black carbonaceous clay, shale, or slate, used as a pigment or crayon.

black cobalt

See: asbolan.

black concentrate

The mixture of amalgam gold and magnetite obtained from behind the riffles in a gold sluice.

black copper

A name given to the impure metallic copper produced in blast furnaces running on oxide ores or roasted sulfide material; an alloy of copper with one or more other metals generally containing several percent of iron, commonly lead, and many other impurities; also contains 1% to 3% sulfur. See also: tenorite.

black copper ore

An earthy, black, massive, or scaley form of copper oxide, CuO. See also: melaconite; tenorite.

black coral

An intense black to dark brown coral used in beads, bracelets, art objects, etc.

black cotton

In India, soil from 6 to 10 ft (1.8 to 3.0 m) in thickness overlying the coal measures, which, in dry weather, shrinks and produces mud cracks.


Generally applied to carbon dioxide. Strictly speaking, a mixture of nitrogen and carbon dioxide. The average blackdamp contains 10% to 15% carbon dioxide and 85% to 90% nitrogen. It is formed by mine fires and the explosion of combustible gases in mines, and hence forms a part of the afterdamp. An atmosphere depleted of oxygen rather than containing an excess of carbon dioxide. Being heavier than air, it is always found in a layer along the floor of a mine. It extinguishes light and suffocates its victims. Hence, it is sometimes known as chokedamp. See also: afterdamp; damp.

black diamond

a. A variety of crystalline carbon, related to diamond, but showing no crystal form. Highly prized as an abrasive because of its hardness. Occurs only in Brazil. Syn: carbonado.

b. A term frequently applied to coal. c. A black gem diamond. d. Dense black hematite that takes a polish like metal.

black flux

A reducing flux composed of powdered carbon and alkali-metal carbonate.

black garnet

See: andradite.

black gold

a. A slang American term referring to crude oil.

b. Syn: Maldonite. c. Placer gold coated with a black or dark-brown substance (such as a film of manganese oxide) so that the yellow color is not visible until the coating is removed.

black granite

A commercial term for crystalline rock that when polished is dark gray to black. It may be a diabase, diorite, or gabbro.

black gunpowder

A mixture of potassium nitrate (saltpeter), sulfur, and charcoal in varying proportions. A typical composition is 70% to 75% saltpeter, 10% to 14% sulfur, and 14% to 16% charcoal. It is designated according to grain size: mealed; superfine grain (FFG); fine grain (FG); large or coarse grain (LG); large grain for rifles (RLG); and mammoth. Syn: black powder.

black hematite

See: psilomelane.

black iron

Malleable iron, untinned; distinguished from tinned or white iron.

black iron ore

See: magnetite.


a. A thin stratum of coal interbedded with layers of slate; a slaty coal with a high ash content.

b. A syn. of sphalerite, esp. a dark variety. See also: sphalerite.

black lead

a. An obsolete name for graphite, still used in naming lead pencils, which are really made of graphite. Syn: plumbago.

b. Graphite, in impure crystalline form. c. Used for coating patterns and the faces of cast-iron chilling molds.

blacklead ore

An early name for the black variety of cerussite.

black light

a. A prospector's and miner's term for ultraviolet light, used in exploration and evaluation to detect mineral fluorescence.

b. An instrument, usually portable, that produces ultraviolet light for this purpose. See also: lamp.

black liquor

The alkaline spent liquor from the digesters in the manufacture of sulfate or soda wood pulp.

black liquor recovery furnaces

Smelting or recovery furnaces in which evaporated black liquor is burned to a molten chemical smelt.


See: anthracosis.

black magnetic rouge

A polishing material consisting of 99% Fe (sub 3) O (sub 4) . See also: black rouge.

black manganese

a. See: hausmannite.

b. A term applied to dark-colored manganese minerals; e.g., pyrolusite, hausmannite, and psilomelane.

black metal

A black shale associated with coal measures.

black mica

See: biotite.

black muck

Lanc. A dark-brown powdery substance, consisting of silica, alumina, and iron; found in iron mines.

black mud

A mud formed in lagoons, sounds, or bays, in which there is poor circulation or weak tides. The color is black because of iron sulfides and organic matter.

black ocher

See: wad; bog manganese.

black opal

Precious opal with play of color (commonly red or green) displayed against a dark gray (rarely black) body color; e.g., the fine Australian blue opal with flame-colored flashes.

black ore

a. Eng. Partly decomposed pyrite containing copper.

b. In uranium mining, the term may mean ore containing a high proportion of pitchblende, uraninite, coffinite, or vanoxite. c. Cumb. A variety of hematite in hard pieces, some kidney shaped, reaching the size of one's hand, in a moderately soft, dark-red, brown, or nearly black mass of smit clay and manganese oxide, the whole having a most confused appearance.

black oxide of manganese

See: pyrolusite.

black pigment

Lampblack obtained by burning common coal tar.

black powder

A deflagrating or low-explosive granular compound of sulfur, charcoal, and an alkali nitrate, usually potassium or sodium nitrate. Syn: black gunpowder.

black roast

In fluidization roasting (fluosolids process), the conversion of iron sulfide to magnetite.

black rouge

A precipitated black magnetic iron oxide. Used mainly in plate printing inks and in paints, but has small abrasive applications. See also: black magnetic rouge.

black sand

a. An alluvial or beach sand consisting predominantly of grains of heavy, dark minerals or rocks (e.g., magnetite, rutile, garnet, or basaltic glass), concentrated chiefly by wave, current, or surf action. It may yield valuable minerals. See also: beach placer.

b. An asphaltic sand.

black shale

a. A dark, thinly laminated carbonaceous shale, exceptionally rich in organic matter (5% or more carbon content) and sulfide (esp. iron sulfide, usually pyrite), and often containing unusual concentrations of certain trace elements (U, V, Cu, Ni). It is formed by partial anaerobic decay of buried organic matter in a quiet-water, reducing environment (such as in a stagnant marine basin) characterized by restricted circulation and very slow deposition of clastic material. Fossil organisms are preserved as a graphitic or carbonaceous film or as pyrite replacements. Syn: biopelite.

b. Usually a very thin-bedded shale, rich in sulfides (esp. pyrite, which may have replaced fossils) and rich in organic material, deposited under barred basin conditions causing anaerobic accumulation. c. Generally, a fine-grained, finely laminated carbonaceous shale, sometimes canneloid, often found as a roof to a coal, or in place of a coal, resting on a fire clay. Syn: black metal.

black silver

See: stephanite.

black smoker

A hydrothermal vent at the crest of an oceanic ridge; e.g., the East Pacific Rise at the mouth of the Gulf of California. Waters blackened by sulfide precipitates jet out at 1 to 5 m/s at temperatures of at least 350 degrees C. The term refers to uprushing black turbulent suspension. CF: white smoker.

black telluride

See: nagyagite.

black tellurium

a. A rare gray metallic mineral, a sulfotelluride of gold and lead with some antimony.

b. See: nagyagite.

black tin

Eng. Dressed tin ore ready to be smelted; from Cornwall. See also: cassiterite.

black wad

An early name for several minerals, including graphite and the softer manganese oxides.

bladder pump

A positive displacement pump in which compressed air is forced down an input column to squeeze a water-filled bladder, thereby forcing water up a discharge column to the ground surface. The bladder refills by gravity flow at the end of each lifting cycle, because the bladder unit is below the static water lever. See: positive displacement pump.


a. The shape of a solid, as one in which the ratios of breadth to length and thickness to breadth are each less than 2:3.

b. Having the appearance of blades, e.g., flat crystals strongly elongated in one direction.


Decidedly elongated and flattened; descriptive of some minerals.

bladed structure

Consisting of individual minerals flattened like a knife blade.

blade mill

Trommel washer with lifting blades, which aid in disintegration and scrubbing of passing feed.


a. A Scottish term for a gray-blue carbonaceous shale that weathers to a crumbly mass and eventually to a soft clay. See also: bind.

b. A Scottish term for a hard, joint-free sandstone. Syn: blaize.

Blair process

An improved form of the Chenot process for making sponge iron by heating crushed iron oxide and coal in retorts.

Blaisdell excavator

An apparatus for automatically discharging a sand tank having a central bottom opening. It consists of a central vertical shaft carrying four arms fitted with round plow disks. Sand is plowed toward a central opening and discharged on a conveyor belt. Syn: Blaisdell vat excavator.

Blaisdell loading machinery

An apparatus for loading sand tanks. It consists of a rapidly revolving disk with curved radial vanes. The disk is hung on a shaft in the tank center, and the sand dropped on the disk is distributed over the entire tank area.

Blaisdell vat excavator

See: Blaisdell excavator.


See: blaes.

Blake breaker

A jaw breaker or particular kind of jaw crusher.

Blake furnace

A furnace, the hearth of which consists of terraces rising from the outer edge to the center. The hearth is circular and revolves when in operation.


a. Anhydrous ferric tellurite as reddish-brown microcrystalline (cubic?) crusts from Goldfield, NV.

b. Titanozirconate of thorium, uranium, calcium, iron, etc., described as zirkelite from Ceylon [now Sri Lanka], but differing in chemical composition and also apparently in crystalline form from the original zirkelite from Brazil.

Blake jaw crusher

The original crusher of jaw type. A crusher with one fixed jaw plate and one pivoted at the top so as to give the greatest movement on the smallest lump. Motion is imparted to the lower end of the crushing jaw by toggle joint operated by eccentric. This machine, or some modification of it, is used for reducing run-of-mine ore or coal to a size small enough to be taken by the next crusher in the series during the first stage of crushing.

Blake Morscher separator

See: electrostatic separator.


a. An interval in a borehole from which core was not recovered or was lost, or in which no minerals of value were encountered.

b. See: bit blank. c. In powder metallurgy, a pressed, presintered, or fully sintered compact, usually in the unfinished condition and requiring cutting, machining, or some other operation to produce the final shape. d. A quartz plate with approx., or exactly, the correct edge dimensions, but not yet finished to final thickness (frequency). Ordinarily applied to pieces of quartz that are in the process of being machine lapped or that are diced out, but not yet lapped.

blank bit

See: bit blank.


a. A textile material used in ore treatment plants for catching coarse free gold and some associated minerals; e.g., pyrite. The blanket is taken up periodically and washed in a tub to remove the gold concentrate, from which the gold is recovered by amalgamation. CF: tabular.

b. See: blanket deposit; blanket vein. c. Soil or broken rock left or placed over a blast to confine or direct throw of fragments. d. A thin, widespread sedimentary body whose width-thickness ratio is greater than 1,000:1 and may be as great as 50,000:1. Syn: sheet.

blanket deposit

a. A horizontal, tabular orebody; manto; bedded vein.

b. A sedimentary deposit of great areal extent and relatively uniform thickness; esp. a blanket sand and associated limestones. See also: blanket; blanket vein.

blanket feed

A method for charging batch designed to produce an even distribution of batch across the width of the furnace.


a. The material caught upon the blankets used in concentrating gold-bearing sands or slimes; also the process involved.

b. Can. Staking but not recording claims.

blanket sand

A blanket deposit of sand or sandstone of unusually wide distribution, typically an orthoquartzitic sandstone deposited by a transgressive sea advancing for a considerable distance over a stable shelf area; e.g., the St. Peter Sandstone of the East-Central United States. Syn: sheet sand; blanket sandstone.

blanket sandstone

See: blanket sand.

blanket shooting

Applied to a method of blasting on a face not exceeding 30 ft or 35 ft (9.1 m or 10.7 m) in height. It involves leaving at the quarry face a mass of shattered rock several feet in thickness that serves as a buffer, preventing the rock from being thrown far from its source, and also rendering the shot more effective. Syn: buffer shooting; shooting against the bank.

blanket sluice

A sluice in which coarse blankets are laid to catch the fine but heavy particles of gold, amalgam, etc., in the slime passing over them. The blankets are removed and washed from time to time to obtain the precious metal.

blanket strake

A trough over which gold pulp flows. It is lined with a blanket for catching coarse gold and associated minerals. See also: strake.

blanket vein

A horizontal or sheet deposit. See also: blanket; blanket deposit. CF: bed vein.

blanket washer

In ore dressing, smelting, and refining, one who cleans flannel blankets over which a mixture of finely ground gold ore and cyanide solution from Chilean mills is passed to collect free particles of gold not dissolved by the cyanide.

blank hole

a. A borehole in which no minerals or other substances of value were penetrated. Syn: barren hole; dry hole.

b. The uncased portion of a borehole. Syn: bare; barefoot; naked.


To line a specific portion of a borehole with casing or pipe for the purpose of supporting the sidewalls or to prevent ingress of unwanted liquids or gas. Syn: case; case off CF: seal off.

blank pipe

Unperforated pipe or casing set in a borehole.

blank reaming shell

A reaming shell in which no reaming diamonds or other cutting media are inset on the outside surface.

Blanton cam

A device used for locking the cam on the camshaft in a stamp mill.

Blasjo cut

This is a cut with a single V where all the holes on one side are parallel and meet the holes from the other side at an angle that may be as low as 30 degrees .


a. The ignition of a heavy explosive charge. Syn: shot.

b. A miner's term for compressed air underground. c. Scot. A fall of water in the downcast shaft to produce or quicken ventilation. d. A suffix signifying a texture formed entirely by metamorphism. e. The operation of increasing the diamond exposure on a bit face by removing some of the matrix metal through the abrasive action of grains of sand carried in a high-pressure stream of air. Also called sandblast. f. An increase in firing temperature of a kiln immediately before ending the firing operation. g. The period during which a blast furnace is in blast; i.e., in operation.

blast coupling

The degree to which an explosive fills the borehole. Bulk-loaded explosives are completely coupled. Untamped cartridges are decoupled.

blast draft

The draft produced by a blower, as by blowing in air beneath a fire or drawing out the gases from above it. A forced draft.


a. A device for detonating an explosive charge.

b. One who sets off blasts in a mine or quarry. A shot firer. Syn: shooter. c. See: blasting unit.

blast furnace

A shaft furnace in which solid fuel is burned with an airblast to smelt ore in a continuous operation.

blast furnace dust

A dust recovered from blast furnace gases, some of which is valuable for its potash content.

blast furnace gas

A low-grade producer gas, made by the partial combustion of the coke used in the furnace and modified by the partial reduction of iron ore. The gas contains more carbon dioxide and less hydrogen than normal producer gas made from coke and has a lower calorific value.

blast-furnace slag

The nonmetallic product, consisting essentially of silicates and aluminosilicates of lime and of other bases, that is developed simultaneously with iron in a blast furnace. Syn: slag.

blast hearth

A hearth in connection with which a blast is used, as in reducing lead ore.


A hole drilled in a material to be blasted, for the purpose of containing an explosive charge.

blasthole charger

A portable unit consisting of a prilled explosive reserve tank feeding into an air-activated loading tube. The equipment should be grounded to guard against buildup of static electricity and possible accidental explosive detonation. The blasthole charger permits rapid loading of prilled explosives into blastholes drilled in any direction.

blasthole drill

Any rotary, percussive, fusion-piercing, churn, or other type of drilling machine used to produce holes in which an explosive charge is placed. Syn: shothole drill.

blasthole driller

See: churn-drill operator.

blasting agent

An explosive material that meets prescribed criteria for insensitivity to initiation. It is a material or mixture consisting of fuel and oxidizer used in blasting, but not otherwise defined as an explosive. The finished mixture used for shipment or transportation cannot be detonated by a No. 8 test detonator cap when unconfined.

blasting barrel

A piece of iron pipe, usually about 1/2 in (1.3 cm) in diameter, used to provide a smooth passageway through the stemming for the miner's squib. It is recovered after each blast and used until destroyed.

blasting cap

a. A detonator containing an ignition explosive mixture, a primary initiating charge, and a high-explosive base charge, encapsulated in an aluminum or copper shell. Caps are initiated either electrically or nonelectrically. See also: waterproof electric blasting cap.

b. A small sensitive charge placed in the larger explosive charge by which the larger charge is detonated. See also: electric detonator.

blasting cartridge

A cartridge containing an explosive to be used in blasting.

blasting circuit

A shotfiring cord together with connecting wires and electric blasting caps used in preparation for the firing of a blast in mines, quarries, and tunnels.

blasting compounds

Explosive substances used in mining and quarrying.

blasting cord

See: shot-firing blasting cord.

blasting curtain

A screen erected to prevent damage to equipment and supports in the vicinity of the blasting point. See also: curtain; shot-firing curtain. Syn: blasting cord.

blasting fuse

a. A slow-burning fuse used in blasting operations.

b. A fine core of gunpowder enclosed in the center of jute, yarn, etc., for igniting an explosive charge in a shothole. See also: safety fuse.

blasting galvanometer

An instrument that provides a simple means for testing electric blasting circuits, enabling the blaster to locate breaks, short circuits, or faulty connections before an attempt is made to fire the shot. With its use, misfires may be prevented to a great extent. To test a circuit, one wire should be placed on one terminal of the instrument and the other wire on the other terminal. If the needle is not deflected, it indicates that the circuit is broken; if it is an electric blasting cap that is being tested, this should be discarded.

blasting gelatin

A high explosive, consisting of nitroglycerin and nitrocotton. It is a strong explosive, and a rubberlike, elastic substance, unaffected by water. Taken as a standard of explosive power. CF: dynamite.

blasting hole well driller

See: churn-drill operator.

blasting log

A written record of information about a specific blast as may be required by law or regulations.

blasting machine

A portable dynamo that generates enough electric current to detonate electric blasting caps when the machine rack bar or handle is given a quick, downward push. Syn: battery. See also: dynamo exploder; M.E. 6 exploder.

blasting mat

A mat of woven steel wire, rope, scrap tires, or other suitable material or construction to cover blastholes for the purpose of preventing flying rock missiles.

blasting needle

A pointed instrument for piercing the wad or tamp of a charge of explosive, to permit introducing a blasting fuse.

blasting off the solid

Blasting the working face in a coal mine without providing a second free face by cutting or shearing before blasting.

blasting oil

See: nitroglycerin.

blasting reflection mechanism

See: reflection mechanism.

blasting supplies

A term used to include electric blasting caps, ordinary blasting caps, fuse, blasting machines, galvanometers, rheostats, etc., in fact, everything used in blasting, except explosives. CF: blowing tools.

blasting switch

A switch used to connect a power source to a blasting circuit. It is sometimes used to short-circuit the leading wires as a safeguard against premature blasts.

blasting timer

An instrument that utilizes a powerline as a source of electrical current and that closes the circuits of successive blasting caps with a delay time interval. The timer provides for the circuits of 15 charges and affords positive control of the duration of intervals.

blasting tube

A tube of explosives, as nitroglycerin, for blasting.

blasting unit

A portable device including a battery or a hand-operated generator designed to supply electric energy for firing explosive charges in mines, quarries, and tunnels. Syn: blaster; exploder; shot-firing unit. See also: single-shot blasting unit; multiple-shot blasting unit.

blasting vibrations

The energy from a blast that manifests itself in earthborne vibrations that are transmitted through the Earth away from the immediate blast site. Syn: ground vibrations.

blast nozzle

A fixed- or variable-sized outlet of a blast pipe.


A relict texture in a metamorphic rock in which remnants of the original granitic texture remain.


Said of a relict texture in a metamorphic rock in which traces of an original ophitic texture remain.


Said of a relict texture in a metamorphic rock in which traces of an original porphyritic texture remain.

blast pattern

The array of drilled holes on the surface or underground to be loaded and detonated in sequence; a pattern is indicated by the distance between holes in a row (spacing) and between rows (burden).

blast roasting

Roasting conducted in a Dwight-Lloyd machine, in which roasting is accompanied by sintering. The charge is placed in small boxes and ignited; air is then drawn through to burn off sulfur. Syn: Carmichel-Bradford process.

blast site

The area where explosive material is handled during the loading and detonation of blast holes; in surface blasting, it includes 50 ft (15.2 m) in all directions from perimeter holes; underground, it includes 15 ft (4.6 m) of solid rib.

bleaching clay

A clay or earth that, either in its natural state or after chemical activation, has the capacity for adsorbing or removing coloring matter or grease from liquids (esp. oils). Syn: bleaching earth.

bleaching earth

See: bleaching clay.


A small, usually rounded inclusion of one mineral in another; e.g., blebs of olivine poikilitically enclosed in pyroxene.

bled ingot

In steelmaking, an ingot that has lost its molten center while cooling.


a. A connection located at a low place in an air line or gas line, or container, so that by means of a small valve the condensed water or other liquid can be drained or bled off from the line or container without discharging the air or gas.

b. A fine-adjustment valve (needle valve) connected to the bottom end of a hydraulic feed cylinder in the swivel head of a diamond drill. By means of the bleeder, the speed at which the hydraulic piston travels can be minutely controlled. c. A pipe on top of an iron blast furnace through which gas escapes.

bleeder entries

Widely used for draining methane in coal mines in the United States where the room-and-pillar method is employed. They are panel entries driven on a perimeter of a block of coal being mined and maintained as exhaust airways to remove methane promptly from the working faces to prevent buildup of high concentrations either at the face or in the main intake airways. They are maintained, after mining is completed, in preference to sealing the completed workings.

bleeder pipe

A pipe inserted in a seal to relieve gas pressure from a sealed area.


a. The process of giving off oil or gas from pore spaces or fractures; it can be observed in drill cores.

b. The exudation of small amounts of water from coal or a stratum of some other rock.

bleeding surface

Any face, such as the walls of a well or borehole or the sides of a fracture, that traverses a reservoir rock or aquifer, permitting the stored liquid or gas to seep (or to bleed) into the opening.

bleed off

A coal mining term used when feeders or blowers act as the means by which gas is "bled off" or dissipated to the adjoining strata or to the surface.


a. Without specific qualification, it means zincblende or the sulfide of zinc (sphalerite), which has the luster and often the color of common resin and yields a white streak and powder. The darker varieties are called blackjack by English miners. Other minerals having this luster are also called blendes, such as antimony blende, ruby blende, pitchblende, and hornblende. Sphalerite (blende) is often found in brown shining crystals, hence its name among German miners, from the word blenden, meaning to dazzle.

b. A miners' term for sphalerite. c. Various minerals, chiefly metal sulfides, with bright or resinous but nonmetallic luster, e.g., zinc blende (sphalerite), antimony blende (kermesite), bismuth blende (eulytite), cadmium blende (greenockite), pitchblende (uraninite), hornblende.

blended unconformity

An unconformity having no distinct surface of separation or sharp contact, as at an erosion surface that was originally covered by a thick residual soil, which graded downward into the underlying rocks and was partly incorporated in the overlying rocks; e.g., a nonconformity between granite and overlying basal arkosic sediments derived as a product of its disintegration. Syn: graded unconformity.


Mixing in predetermined and controlled quantities to give a uniform product.

blending conveyor

A conveyor running beneath a line of ore bins or stockpiles, and so set that each bin or stockpile can deliver onto the conveyor at a controllable rate from individual feeders. Syn: paddle-type mixing conveyor; screw-type mixing conveyor.


a. To drill with the circulation medium (water or drill mud) escaping into the sidewalls of the borehole and not overflowing the collar of the drill hole.

b. An underground opening not connected with other workings nearby and at about the same elevation. c. Said of a mineral deposit that does not crop out. The term is more appropriate for a deposit that terminates below the surface than for one that is simply hidden by unconsolidated surficial debris. Syn: blind vein.

blind apex

The near-surface end of a mineral deposit, e.g., the upper end of a seam or vein that is truncated by an unconformity. Syn: buried outcrop.

blind bit

See: noncoring bit.

blind borehole process

In the underground gasification of coal, a borehole is drilled to a blind end having no outside connection. A tube of smaller diameter is inserted nearly the full length through which air is passed to supply a gasification reaction at the far end of the hole. The hot gases return around the outside of the tube. See also: underground gasification.

blind drift

A horizontal passage, in a mine, not yet connected with the other workings. See also: blind level.


See: blende.

blind header

A concealed brick header in the interior of a wall, not showing on the faces.

blind hole

A borehole in which the circulating medium carrying the cuttings does not return to the surface.


a. In leaching, reduced permeability of ion-exchange resins due to adherent slimes. In sieving, blocking of screen apertures by particles.

b. A matting of, or stoppage by, fine materials during screening that interferes with or blinds the screen mesh. c. Compacting soil immediately over a tile drain to reduce its tendency to move into the tile.

blind joint

In apparently massive rock that is being quarried, a plane of potential fracture along which the rock may break during excavation.

blind lead

A vein having no outcrop. See also: blind lode; blind vein; lead.

blind level

a. One not yet holed through to connect with other passages. Syn: blind drift.

b. A cul-de-sac or dead end. c. A level for drainage, having a shaft at either end, and acting as an inverted siphon.

blind lode

A lode showing no surface outcrop, and one that cannot be found by any surface indications. See also: blind lead; blind vein.

blind road

Mid. Any underground roadway not in use, having stoppings placed across it. Syn: blind way.

blind roaster

A muffle furnace for roasting ore out of contact with the products of combustion.

blind seams

Incipient joints.

blind shaft

A sublevel shaft, connected to the main (daylight to depth) shaft by a transfer station. A winze.

blind shearing

Scot. A side cutting without undercutting.

blind vein

A vein that does not continue to the surface. See also: blind; blind lode; blind lead.

blind way

See: blind road.

blind zone

See: shadow zone.


Echo trace on radar or sonar indicator screen.

Bliss sandstone

Massive, compact, fine-textured, fossiliferous gray sandstone ranging from almost white to brown. It may be either Cambrian or Ordovician, or both, at any given locality. It represents a period of slow intermittent deposition of sandy material. Found in New Mexico and in Texas.


a. In quarrying, an unconfined charge of explosive used to bring down dangerous ground that cannot be made safe by barring and that is too inaccessible to bore.

b. A protrusion, more or less circular in plan, extending downward into a coal seam. It represents the filling of a streambed pothole worn into the upper surface of the coal-forming material. c. Copper as a smelter product before it is refined. d. A defect in metal, on or near the surface, resulting from the expansion of gas in a subsurface zone. Very small blisters are called pinheads or pepper blisters.

blister bar

A wrought-iron bar impregnated with carbon by heating in charcoal. Used in making crucible steel.

blister copper

An impure intermediate product in the refining of copper, produced by blowing copper matte in a converter.

blistered copper ore

A reniform variety of chalcopyrite.

blister steel

Raw steel that has been cooled very slowly and that has a blistered appearance. The blisters are formed by gas escaping from within the metal.

blister wax

See: blower wax.

bloating phenomena

The expansion of certain nonmetallic materials by heating until the exterior of the particle or shape becomes sufficiently pyroplastic or melted to entrap gases generated on the interior by the decomposition of gas-producing components.


a. A division of a mine, usually bounded by workings but sometimes by survey lines or other arbitrary limits.

b. A short piece of timber placed between the mine roof and the cap of a timber set and directly over the cap support. A wedge driven between the roof and the timber holds the set in place. See also: blocking and wedging. c. A pillar or mass of ore exposed by underground workings. See also: blocking out. d. Portion of an orebody blocked out by drives, raises, or winzes, so that it is completely surrounded by passages and forms a rectangular panel. If its character, volume, and assay grade are thus established beyond reasonable doubt, it ranks as proved ore in the mine's assets. e. The wedging of core or core fragments or the impaction of cuttings inside a bit or core barrel, which prevents further entry of core into the core barrel, thereby producing a condition wherein drilling must be discontinued and the core barrel pulled and emptied to forestall loss of core through grinding or the serious damage of the bit or core barrel. See also: core block; plug. f. An obstruction in a borehole. g. See: sheave.

block caving

A general term that refers to a mass mining system where the extraction of the ore depends largely on the action of gravity. By removing a thin horizontal layer at the mining level of the ore column, using standard mining methods, the vertical support of the ore column above is removed and the ore then caves by gravity. As broken ore is removed from the mining level of the ore column, the ore above continues to break and cave by gravity. The term "block caving" probably originated in the porphyry copper mines, where the area to be mined was divided into rectangular blocks that were mined in a checkerboard sequence with all the ore in a block being removed before an adjacent block was mined. This sequence of mining is no longer widely used. Today most mines use a panel system, mining the panels sequentially or by establishing a large production area and gradually moving it forward as the first area caved becomes exhausted. The term "block caving" is used for all types of gravity caving methods. There are three major systems of block caving, and they are differentiated by the type of production equipment used. (1) The first system based on the original block cave system is the grizzly or gravity system and is a full gravity system wherein the ore from the drawpoints flows directly to the transfer raises after sizing at the grizzly and then is gravity loaded into ore cars. (2) The second system is the slusher system, which uses slusher scrapers for the main production unit. (3) The last system is the rubber-tired system, which uses load-haul-dump (LHD) units for the main production unit. Block caving has the lowest cost of all mine exploitation systems, with the exception of open pit mining or in situ recovery. See also: top slicing.

block caving into chutes

See: chute caving.

block claim

Aust. A square mining claim whose boundaries are marked out by posts.

block diagram

A plane figure representing a block of the Earth's crust (depicting geologic and topographic features) in a three-dimensional perspective, showing a surface area on top and including one or more (generally two) vertical cross sections. The top of the block gives a bird's-eye view of the ground surface, and its sides give the underlying geologic structure.

blocked-out ore

a. Ore, the amount, content, and minability of which have been proven by development work or by drilling developed ore. Syn: developed reserve.

b. A body of ore exposed, explored, and sampled for valuation purposes on all four sides of the panel formed by driving, winzing, and raising. c. See: reserves.

block faulting

A type of normal faulting in which the crust is divided into structural or fault blocks of different elevations and orientations. It is the process by which block mountains are formed.

block field

A thin accumulation of usually angular blocks, lying on bedrock without a cliff or ledge above as apparent source. Block fields occur on high mountain slopes above the tree line. Syn: felsenmeer.

block hole

a. A small hole drilled into a rock or boulder into which an anchor bolt or a small charge or explosive may be placed.

b. Used by drillers, miners, and quarry workers for a method of breaking undesirably large blocks of stone or boulders by the discharge of an explosive loaded into shallow holes drilled into the blocks or boulders. c. A relief hole designed to remove part of the burden from a subsequent shot; used in coal mining.


A person whose duty it is to break up and reduce to safe and convenient size, by blasting or otherwise, any large blocks or pieces of rock that have been blown down by the miners.

block hole shot

See: pop shot.


The breaking of boulders by loading and firing small explosive charges in small-diameter drilled holes.


In a crusher, obstruction of the crushing zone by clayey material or by rock that refuses to break down and pass to discharge. Syn: packing.

blocking and wedging

A method of holding mine timber sets in place. Blocks of wood are set on the caps directly over the post supports and have a grain of block parallel with the top of the cap; wedges are driven tightly between the blocks and the roof. See also: block.

blocking out

a. Exposing an orebody by means of development openings, on at least three sides, in preparation for continuous extraction; the opening of a deep lead deposit. See also: block.

b. As applied to coal reserves, acquiring coal and mining rights in contiguous areas to form a continuous area and in a desirable shape for planned future mining. c. Aust. Laying or staking out gold-bearing gravel deposits in square blocks in order to facilitate systematic washing. d. In economic geology, delimitation of an orebody on three sides in order to develop it, i.e., to make estimates of its tonnage and quality. The part so prepared is an ore block.

block kriging

Estimating the value of a block from a set of nearby sample values using kriging.


Applied to the various processes involved in roofing slate manufacture, which include drilling and wedging, cutting, sawing, etc.

block mica

Mica with a minimum thickness of 0.007 in (0.18 mm) and a minimum usable area of 1 in (super 2) (6.45 cm (super 2) ), full trimmed unless otherwise specified.

block mountain

A mountain that is formed by block faulting. The term is not applied to mountains that are formed by thrust faulting. Syn: fault-block mountain.

block movement

A general failure of the hanging wall. In the gold mines of South Africa and the Michigan copper mines, block movements have been experienced.

block off

a. To fill and seal undesirable openings, fissures, or caving zones in a borehole by cementation or by lining the borehole with pipe or casing. Also called blank off; case off; seal off.

b. To secure a mine opening against the flow or escape of gas, air, or liquid by erecting rock, concrete, steel, wood, or cloth barriers. c. To erect barriers to prevent workers from entering unsafe areas in underground workings.

block out

To delineate the area in which a desirable mineral occurs by systematic core drilling or by underground openings.

block riffles

These consist of timber blocks, 8 to 12 in (20.3 to 30.5 cm) square, set in transverse rows in a sluicebox; they are arranged so that in contiguous rows the joints are staggered to prevent the development of longitudinal cracks. It is usual to separate adjacent rows by means of a strip of ordinary riffle scantling.

block structure

Used in quarrying to describe granite that has three sets of joints occurring at right angles to each other.

block system

a. A pillar mining system in which a series of entries, panel entries, rooms, and crosscuts are driven to divide the coal into blocks of approx. equal size, which are then extracted on retreat. Development openings are most commonly driven between 15 ft and 20 ft (4.6 m and 6.1 m) wide. Pillars are most commonly 40 to 60 ft (12.2 to 18.3 m) wide and from 60 to 100 ft (18.3 to 30.5 m) long.

b. A system of control in which a number of units, for example, powered supports, are operated as a group.

block system of stoping and filling

See: overhand stoping; Brown panel system.

block-tin lining

Copper vessels are lined or coated with tin by the application of molten tin upon clean copper with the aid of fluxing.

blocky rock

Rock ore that breaks into large blocks.


A monoclinic mineral, Na (sub 2) Mg(SO (sub 4) ) (sub 2) .4H (sub 2) O . Also spelled bloedite, blodite. Formerly called astrakhanite. Syn: astrakanite; magnesium blodite.

Bloman tube breathing apparatus

This differs from the smoke helmet in that there is neither helmet nor bellows. Fresh air is passed to the wearer through a corrugated reinforced rubber tube by means of a rotary blower. A mouthpiece having an inhalation valve, an exhalation valve, and a noseclip takes the place of the helmet. It is held in position by straps attached to a head harness. The mouthpiece can be replaced by a full-face mask. This apparatus is fitted with an equalizing device that enables the wearer to continue breathing comfortably, even should the rotary blower stop.


See: priorite.


with small red spots. Used as a gem. Also called heliotrope. CF: plasma.

b. A red variety of quartz.

blooey line

A pipe or flexible tube conducting cuttings-laden air or gas from the collar of a borehole to a point far enough removed from the drill rig to keep the air around the drill dust free.


a. A mineral that is frequently found as an efflorescence, cobalt bloom, for example. Syn: efflorescence.

b. To form an efflorescence; as, salts with which alkali soils are impregnated bloom out on the surface of the Earth in dry weather following rain or irrigation. c. The fluorescence of petroleum or its products. d. A semifinished hot-rolled product, rectangular in cross section, produced on a blooming mill. For iron and steel, the width is not more than twice the thickness, and the cross-sectional area is usually not less than 36 in (super 2) (232 cm (super 2) ). Iron and steel blooms are sometimes made by forging. e. A surface film resulting from attack by the atmosphere or from the deposition of smoke or other vapors. f. A lump or mass of molten glass.


See: blooming mill.


A forge for making wrought iron, usually direct from the ore. Syn: cinder plate; Merrit plate.

blooming mill

The mill or equipment used in reducing steel ingots to blooms.


a. A sudden escape of gas from coal or associated strata into mine workings. See also: outburst.

b. A large outcrop of ore, commonly of low grade. c. To lift: said of a floor that lifts owing to pressure from gas or strata. d. In blasting, a shot that blows part of the unfired explosive out of the hole. See also: blown-out shot. e. To fire shots.

blow count

The number of blows that must be delivered by a specific-weight, freely falling drive hammer dropping a specific distance to force a drive sampler a unit distance into a soil material.


a. A fan employed in forcing air either into a mine or into one portion of a mine. A portable blower, also known as a tubing blower or room blower, is used in ventilating small dead-end places like rooms and entries or gangways.

b. The sudden emission of combustible gases from the coal seam or surrounding rock. Blowers vary considerably in violence and magnitude from small emissions that make a hissing noise to severe outbursts. c. Eng. A worker who blasts or fires shots in a mine, or who drills the holes and charges them, ready for firing.

blower fan

A fan to direct part of an air circuit through a tubing to a particular working face. See also: mine ventilation auxiliary fan.

blower system

A system in which the pressure-generating source is located at the entrance and raises the pressure of the air above atmospheric.

blower wax

A pale yellow, soft variety of ozocerite that is squeezed out of the veins under the influence of pressure of the surrounding rocks. Syn: blister wax.


a. A minute crater formed on the surface of thick lava flows.

b. A hole in a casting or a weld caused by gas entrapped during solidification. See also: gas evolution.

blow in

To put a blast furnace in operation. Syn: blowing in.


a. Oxidation of molten metal or matte in a converter or other smelting furnace, in order to remove carbon and sulfur and to convert impurities to slag.

b. The bursting of pots from too rapid heating.

blowing engine

An engine for forcing air into blast furnaces under pressure, commonly about 1 psi (6.9 kPa).

blowing in

Starting a blast furnace. Syn: blow in.

blowing on taphole

Blowing air through the hole at casting, to clean the hearth of iron and cinder.

blowing road

S. Staff. An intake, or fresh-air road in a mine.

blowing tools

A small set of blasting implements. CF: blasting supplies.

blowing-up furnace

A furnace used for sintering ore and for the volatilization of lead and zinc.

blowing ventilation

Mine ventilation in which the air flows from the fan at the portal toward the working face.

blown metal

Pig iron purified by blowing air through it.

blown-out shot

A shot that dissipates the explosive force by blowing out the stemming instead of breaking down the coal. It may be caused by insufficient stemming, overcharging with explosive, or a burden that is too much for the charge to dislodge. See also: gun; blow. Syn: cannon shot; gunned shot.


a. A large mineralized outcrop beneath which the vein is smaller, e.g., a great mass of quartz that conceals a vein only a few feet wide.

b. A shot or blast that goes off like a gun and does not shatter the rock; a windy shot. c. A large outcrop beneath which the vein is smaller is called a blowout. (slang) d. The high-pressure, sometimes violent, and uncontrolled ejection of water, gas, or oil from a borehole. e. Used by prospectors and miners for any surface exposure of strongly altered discolored rock associated, or thought to be associated, with a mineral deposit. f. Used by miners and prospectors for a large, more or less isolated, usually barren quartz outcrop. Known in Australia as blow. g. To put a blast furnace out of blast, by ceasing to charge fresh materials, and continuing the blast until the contents of the furnace have been smelted. h. To smelt the iron-bearing materials in the furnace, adding domestic coke so that the stockline is about normal. i. A general term for a small saucer-, cup-, or trough-shaped hollow or depression formed by wind erosion on a preexisting dune or other sand deposit, esp. in an area of shifing sand or loose soil, or where protective vegetation is disturbed or destroyed; the adjoining accumulation of sand derived from the depression, where recognizable, is commonly included. Some blowouts may be many kilometers in diameter.

blowout shot

An improperly placed or overcharged shot of black blasting powder in coal (where used), frequently results in a mine explosion.


a. Sand blown by onshore winds across a barrier and deposited on its landward side or as a veneer in the lagoon; e.g., along the Gulf Coast of Texas. CF: washover.

b. The process of forming a blowover.

blowpipe reaction

a. The decomposition of a compound or mineral when heated by the blowpipe, resulting in some characteristic reaction, as a coloring of the flame or a colored crust on a piece of charcoal.

b. A method of analysis in mineralogy.


a. A rapid method for the determination of the approximate composition of minerals and ores. Blowpipe tests are merely qualitative; i.e., they indicate the presence of the different constituents, but not the proportions. A blowpipe consists of a plain brass tube capable of producing a flame of intense heat that may be either oxidizing or reducing. Illuminating gas from a Bunsen burner is the fuel commonly used. The color, nature, and smell of the encrustations suggest the nature of the elements present. See also: bead; borax bead test.

b. The use of a bent tube with a condensation trap and a small hole to direct one's concentrated breath into a small flame from a gas or alcohol lamp to produce intense heat in both oxidizing and reducing flames for the purpose of soldering metals or of performing qualitative analyses on powdered mineral samples. See also: oxidizing flame; reducing flame.


a. Eng. An explosion of combustible gases in a mine.

b. To allow atmospheric air access to certain places in coal mines, so as to generate heat, and ultimately to cause gob fires.

blue annealing

Heating hot-rolled ferrous sheet in an open furnace to a temperature within the transformation range, and then cooling it in air in order to soften the metal. The formation of a bluish oxide on the surface is incidental.

blue asbestos

A name for crocidolite, the asbestiform variety of riebeckite.

blue band

A thin, persistent bed of bluish clay that is found near the base of the No. 6 coal throughout the Illinois-Indiana basin.

blue-black ore

Corvusite, extremely high-grade vanadium ore with blue-black color.

blue brittleness

Brittleness exhibited by some steels after being heated to some temperature within the range of 300 to 650 degrees F (149 to 343 degrees C), particularly if the steel is worked at the elevated temperature.

blue cap

The characteristic blue halo, or tip, of the flame of a safety lamp when combustible gases are present in the air. See also: top; cap.

blue chalcedony

See: sapphirine.

blue chalcocite

See: digenite.

blue copper

See: azurite; covellite.

blue copper ore

See: azurite.

blue earth

See: blue ground.

blue gold

a. A gold-iron alloy containing 25% to 33.3% iron.

b. A bluish collodial solution of gold prepared by reducing a solution of gold chloride with hydrazine hydrate.

blue granite

See: larvikite.

blue ground

Unoxidized slate-blue or blue-green kimberlite, usually a breccia (as in the diamond pipes of South Africa) that is found below the surficial oxidized zone of yellow ground. CF: hardebank. Syn: blue earth.

blue iron earth

See: vivianite.

blue ironstone

A bluish iron-bearing mineral; specif: crocidolite and vivianite.

blue lead

a. A term for metallic lead in the lead industry to distinguish it from lead compounds with color designations, such as white lead, orange lead, and red lead. See also: lead.

b. A synonym of galena, esp. a compact variety with a bluish-gray color. Syn: galena; blue lead ore. c. A bluish, gold-bearing lead or gravel deposit found in Tertiary river channels of the Sierra Nevada, CA. Pronounced "blue leed."

blue lead ore

An old name for a compact variety of galena with a bluish-gray color. Pron: led.

blue malachite

An erroneous name for azurite.

blue metal

A term used in England for a hard bluish-gray shale or mudstone lying at the base of a coalbed and often containing pyrite.

blue mud

a. An ocean-bottom deposit containing up to 75% terrigenous materials of dimensions below 0.03 mm. The depth range occurrence is about 750 to 16,800 ft (229 to 5,120 m). Colors range from reddish to brownish at the surface, but beneath the surface, the colors of the wet muds are gray to blue.

b. A common variety of deep-sea mud having a bluish-gray color due to presence of organic matter and finely divided iron sulfides. Calcium carbonate is present in amounts up to 35%.

blue needles

Applied in the grading of quartz crystals to needlelike imperfections, often definitely oriented, which show up with a bluish-white color under the carbon arc. The color is due to the selective scattering of blue light by the minute imperfections.

blue ocher

See: vivianite.

blue powder

A mixture of finely divided and partly oxidized metallic zinc formed by the condensation of zinc vapor into droplets; also, any similar zinc byproduct (such as dross, skimmings, or sweepings).

blue quartz

See: sapphire quartz.

blue-rock phosphate

The hard, bluish-gray, Ordovician bedded phosphates of central Tennessee.

blue room

The first room in a baghouse.

blue schorl

a. Blue tourmaline.

b. The earliest name for anatase (octahedrite).

blue spar

See: lazulite.


a. A commercial name for a building or paving stone of bluish-gray color; specif. a dense, tough, fine-grained, dark blue-gray or slate-gray feldspathic sandstone that splits easily into thin, smooth slabs and that is extensively quarried near the Hudson River in New York State for use as flagstone. The color is due to the presence of fine black and dark-green minerals, chiefly hornblende and chlorite. The term is applied locally to other rocks, such as dark-blue shale and blue limestone. CF: flagstone.

b. A miners' term for chalcanthite. c. A term applied locally to rocks such as dark-blue shale, blue limestone, and bluish metabasalt (greenstone). d. A highly argillaceous sandstone, of even texture and bedding, formed in a lagoon or lake near the mouth of a stream.

blue tops

Grade stakes whose tops indicate finish grade level.

blue vitriol

See: chalcanthite.

blue-white diamond

A diamond that appears blue or bluish in transmitted white light or against a white background; it reflects white light when viewed edge up at right angles to the table.


Derb. A dark tough vein filling that dulls the drills readily.

Blyth elutriator

Laboratory apparatus in which mineral particles suspended in water are syphoned through vertical tubes of increasing cross section, the fraction failing to rise under determined conditions of upward flow reporting as a subsieve fraction.


See: bench mark.

B.M.A.G.A. apparatus

Used in the United States for obtaining additional information on the yields of coke, tar, and gas that can be expected in high-temperature practice. This is a vertical cylinder of mild steel holding up to 2 hundredweight (91 kg) of coal and operated at temperatures up to 1,000 degrees C.