Appendix:Dictionary of Mining, Mineral, and Related Terms/B/5

Definition from Wiktionary, the free dictionary
Jump to: navigation, search


A platform or landing at the top of a shaft. The upper brace is the platform built in the headgear above the shaft collar.

brace head

A cross handle attached at the top of a column of drill rods by means of which the rods and attached bit are turned after each drop in chop-and-wash operations while sinking a borehole through overburden. Also called brace key.

brachy axis

The shorter lateral axis in the crystals of the orthorhombic, monoclinic, and triclinic systems.


a. A pinacoid parallel to the vertical axis and the brachydiagonal.

b. The pinacoid 010 intersecting the brachy-axis in orthorhombic and triclinic systems (obsolete). CF: pinacoid.


In crystallography, comparatively short.


a. Diagonal or horizontal members used to prevent swaying of structures, i.e., conveyor-supporting structures.

b. Eng. See also: lacing.


A monoclinic mineral, Pb (sub 2) (Mn,Fe)(VO (sub 4) ) (sub 2) .H (sub 2) O.

Brackelsberg process

A process by which fine ores are moistened with water to which a binding medium is added, and the wet mass, without any heating, is rotated in a drum until it forms into spherical lumps of varying size. The moisture is then dried out by evaporation, and the product remains in the form of hard, very porous balls of ore, which are of great reducibility as compared with sintered ore or briquettes.


A platform over a shaft entrance.

brackish water

Water in which salinity values range from approx. 0.50 to 17.00 parts per thousand.

Bradford breaker

A machine that combines coal crushing and screening. It consists of a revolving cylindrical screen 8 to 14 ft (2.4 to 4.3 m) in diameter and 13 to 22 ft (4.0 to 6.7 m) in length. It breaks the coal by gravity impact. On reaching the desired size, the coal is discharged through the plates. It can deal with run-of-mine coal up to 12 in (30.5 cm) at a rate of 500 to 600 st/h (454 to 544 t/h), to give a product size of below 1-1/2 in (3.8 cm); other sizes can be produced, depending on the screen plates used. See also: screen.


A monoclinic mineral, Na (sub 3) Mg(PO (sub 4) )(CO (sub 3) ) ; in veryfine grains in saline oil shale in Wyoming.


A long-continued, extremely slow vertical instability of the crust, as in the volcanic district west of Naples, Italy, where the Phlegraean bradyseism has involved up-and-down movements between 6 m below sea level and 6 m above over more than 2,000 yr (Casertano). Etymol: Greek "bradys" (slow) + "seismos" (earthquake).


Insufficiently charred wood, as in charcoal burning.

Bragg angle

The angle, theta , at which X-rays diffract in crystalline materials. It satisfies the relationship n lambda = 2 d sin theta , where d is the distance between diffraction planes of atomic particles in a crystal structure, lambda is the wavelength of the X-rays, and n is the order of diffraction when a crystal is placed in an X-ray beam.

Bragg indices

The index numbers assigned to a diffracted X-ray beam. They have the same values as Miller indices but are written without closures. Diffraction order may be factored into Bragg indices, e.g., 111, 222, 333... represent n = 1, 2, 3... for diffraction from atomic planes parallel to 111 . CF: Miller indices.


A tetragonal mineral (Pt,Pd,Ni)S : steel gray, minute grains in concentrates from the Bushveld norite of the Transvaal, South Africa. A source of platinum and palladium.

braided stream

A stream that divides into an interlacing or tangled network of several small branching and reuniting shallow channels separated from each other by branch islands or channel bars, resembling in plan the strands of a complex braid. Such an anastomosing stream is generally believed to indicate an inability to carry all of its load, such as an overloaded and aggrading stream flowing in a wide channel on a flood plain.


a. A device (as a block or band applied to the rim of a wheel) to arrest the motion of a vehicle, a machine, or other mechanism and usually employing some form of friction.

b. A device, either hand- or power-operated, for applying resistance to the drum or pulley and thus controlling the movement of mine cars or cages. A common form is a brakeshoe, lined with friction material, which is applied to the surface of a wheel or drum, and thus retards or even stops its movement. See also: winder brake. Syn: haulage brake. c. Eng. A stout, wooden lever to which boring rods are attached. It is worked by one or more people. d. N. Staff. To lower trams on dips by means of a wheel and rope.


A rotating cylinder with a machined inner or outer surface upon which a brake band or brakeshoe presses.

brake incline

a. An incline in which the full trucks descend by gravity and pull up the empty ones. See also: gravity haulage.

b. Gravity plane.


a. Person who attends to a brake or brakes, as on a railroad car.

b. Eng. The person in charge of a winding (hoisting) engine for a mine. "Brakeman" is usually used in the United States; "brakesman" is the British usage. The person in charge of hoisting engines, esp. in the United States, is usually called a hoisting engineer. c. In mining, a laborer who rides on trains or trips of cars hauled by locomotive or hoisting cable or chain, and assists in their transportation to surface or shaft bottom for hoisting; operates or throws switches; couples and uncouples cars, or attaches and detaches cars to and from the cable; opens and closes ventilation doors in mines; directs movement of the train by signaling motorman. May be designated according to type of hauling machine, such as dinkey operator helper. Also called brake holder, car rider, conductor, dukey rider, gang rider, motorman helper, nipper, patcher, rider, rope conductor, rope rider, set rider, snapper, tailend rider, trailer, train conductor, trainman, transfer car helper, trip rider, tub rider. Syn: conductor.

brake sieve

A jigger operated by a hand lever.

brake wheel

a. A hand wheel for operating a brake, as on a vehicle.

b. A wheel or pulley on which a friction brake acts. c. A heavy wheel provided with cams for controlling the movement of a triphammer.

braking distance

Tbe distance the haulage unit (i.e., train) will travel after the application of the brakes, depending on the speed, the weight of locomotive and train, and the gradient.


A micaceous mineral differing from illite because it contains soda in excess of potash. Found in crevices in coal measure shales from Llandebie, South Wales. Syn: sodium illite.


See: brasses.


a. An underground road or heading driven in coal measures; also, a roadway turned from a level, etc. Syn: branch hole.

b. A small vein departing from the main lode. CF: main hole.

branch fault

A minor fault that branches from a larger fault.

branch headings

Headings that are turned off the main level at intervals for development purposes. They may proceed to the rise or dip and are adopted in longwall and pillar methods of working. See also: opening out.

branch hole

See: branch.


A variety of hydrocarbon found in lignite. According to Hintz it is identical with hartite.


Clintonite found as monoclinic hexagonal-shaped prisms in metamorphosed limestone.


A monoclinic mineral, (U,Ca,Y,Ce)(Ti,Fe) (sub 2) O (sub 6) ; radioactive; commonly metamict; in placers of the Stanley Basin, UT.


Brittle shale (the coal miner's "slate") interbedded with thin coalbeds; also, the roof of the Pittsburgh coal in western Maryland. See also: rashings.


A paste made by mixing powdered charcoal, coal, or coke with clay, molasses, tar, or other suitable substance. Used for lining hearths, crucibles, etc. Syn: steep.

brasqued crucible

A crucible lined with charcoal or lampblack, and used for the reduction of oxides of metals to the metallic state. The crucible is prepared by ramming it full of lampblack or charcoal, and then excavating a portion of its contents and polishing the lining with a burnisher.

brass balls

Nodular pyrite.


Mineral impurities in coal, of yellow metallic appearance, consisting mainly of iron sulfides. Syn: brances; brassyn.

brassfounder's disease

A disease affecting the general system, characterized by chronic poisoning from inhalation of metallic fumes, with symptoms like those of malarial fever.

brass furnace

One of two kinds of furnaces for the making and founding of brass: (1) a reverberatory furnace for producing large quantities of the alloy, or (2) a crucible furnace for producing small quantities.

brass ore

a. An early name for a mixture of sphalerite and chalcopyrite.

b. An old name for aurichalcite.


See: brasses.

brassy top

Aust. The top part of the Greta coal seam, in which there are large quantities of sulfide of iron.


a. Ventilating partition, usually of coated fabric, used to direct air to various faces to remove gas and dust.

b. A board or plank lining, or other partition, in any mine passage to confine the air and force it into the working places. Its object is to keep the intake air from finding its way by a short route into the return airway. Temporary brattices are often made of cloth. Also spelled braddish; brettice; brettis; brattish. See also: brattice cloth. c. An airtight partition in a mine shaft to separate intake from return air. See also: screen. d. Used as jumpers for removing gas from a roof cavity. e. To provide with a brattice for separation or support; often used with up. Syn: brattice up.

brattice cloth

a. Fire-resistant fabric, usually coated, used to erect a brattice.

b. A heavy canvas, often covered with some waterproofing material, for temporarily forcing the air into the face of a breast or heading; also used in place of doors on gangways; then known as "sheets." Syn: brettice cloth. See also: brattice; brattice sheeting.

brattice man

In mining, a worker who builds doors, stoppings and curtains (ventilation walls or partitions in active workplaces) of burlap, canvas, and wood. Also called airman; braddisher; braddish man; canvasman; doorman; ventilation man.

brattice road

A road through the goaf supported by chocks or timber packs.

brattice sheeting

A curtain or screen of flexible material used to direct or control the flow of ventilating air. See also: brattice cloth; sheets.

brattice up

See: brattice.

brattice worker

See: airman.


See: brattice.


A tetragonal mineral, Mn (super 2+) Mn (super 3+) (sub 6) SiO (sub 12) ; brittle; may contain appreciable iron.


Ger. See: brown coal.


A former name for a micaceous clay later shown to be a mixture of montmorillonite and illite.

Bravais lattice

One of 14 ways points may be arrayed periodically in space such that each point is in an identical point environment. Every crystal structure has associated with it a Bravais lattice. Syn: space lattice; crystal lattice. CF: direct lattice; space group.

Bravais law

See: Bravais rule.

Bravais-Miller indices

See: Miller-Bravais indices.

Bravais rule

The most prominent faces of a crystal are those parallel to internal planes having the greatest density of lattice points. Syn: Bravais law.


A nickeloan variety of pyrite.


To solder with brass or other hard alloys.


A monoclinic mineral, NaAl (sub 3) (PO (sub 4) ) (sub 2) (OH) (sub 4) ; yellow-green; also spelled brasilianite, brasilianita.

Brazilian pebble

A colorless transparent quartz, such as is used for optical purposes.

Brazilian test

A method for the determination of the tensile strength of rock, concrete, ceramic, or other material by applying a load vertically at the highest point of a test cylinder or disk (the axis of which is horizontal), which is itself supported on a horizontal plane. The method was first used in Brazil for testing concrete rollers on which an old church was being moved to a new site.


a. A mixture of baddeleyite, zircon, and altered zircon.

b. A fibrous variety of baddeleyite. c. An oil shale.

Brazil twin

A type of twin found in quartz in which the two crystalline individuals are of opposite kinds, one being right-handed, the other left-handed, with a face of the trigonal prism of the second order as twinning plane. Since one is not derivable from the other by any rotation, there is no twinning axis.


a. Joining metals by flowing a thin layer (capillary thickness) of nonferrous filler metal into the space between them. Bonding results from the intimate contact produced by the dissolution of a small amount of base metal in the molten filler metal, without fusion of the base metal. Sometimes the filler metal is put in place as a thin solid sheet or as a clad layer, and the composite is heated as in furnace brazing.

b. In joining metals, the term "brazing" is used where the temperature exceeds some arbitrary value, such as 800 degrees F (427 degrees C); the term "soldering" is used for temperatures lower than the arbitrary value.


a. An opening made by breaking down a portion of a solid body, as a wall, a dike, or a riverbank; a break; a gap.

b. The face of a level or drift. c. A large cave hole caused by undermining.

breached anticline

An anticline whose crest has been deeply eroded, so that it is flanked by inward-facing erosional scarps. CF: bald-headed anticline.


The breaking through of a bar.


N. Staff. A set of coal pillars formed by rearer workings.


a. A plane of discontinuity in the coal seam such as a slip, fracture, joint, or cleat. The surfaces are in contact or slightly separated. See also: break detector.

b. A fracture or crack in the roof beds as a result of mining operations. See also: breakes; induced fracture. c. To separate core from solid rock at the bottom of a borehole by a tensional pull applied to the drill string. d. In mineral processing, optimum mesh of grind (m.o.g.), the practical size range to which ore is reduced before concentration. Not synonymous with liberation mesh. e. In drilling, to unscrew, as rods, casing, drill pipe, etc.


a. Voluntary or involuntary division of a solid.

b. Small material produced by involuntary breakage during mechanical handling or processing.

breakage clause

Eng. A clause inserted in some mining leases providing for an abatement of royalty or allowance on weight for certain weight of small coal or breakage sent out in every ton of large coal, for example, 120 lb (54.5 kg) in every collier's ton of 2,640 lb (1,200 kg).

breakage of coal

See: degradation.

breakaway chain

A chain that holds a tractor and a towed unit together if the regular fastening opens or breaks. Syn: safety chain.


The fractures caused by the shattering of a solid rock ledge back of the drill holes in which the charge is placed.

break detector

A scraper capable of detecting breaks in a shothole. See also: break; stemmer.


Of an emulsion, the reunion of the finely dispersed particles and their separation from the medium in which they form an emulsion. Syn: hoedown.

breakdown voltage

The voltage at which an insulator or dielectric ruptures; or the voltage at which ionization and conduction begin in a gas or vapor.

breaker capacity

The ability of a switch, in a particular situation, to clear safely the heaviest fault current that can flow; it depends upon the amount of power available in the system, size of cables, transformers, etc. CF: breaking capacity.

breaker props

Props, or props and cribs, set to break the roof off at a prearranged line during retreat mining, or when blasting down roof.


The row of drill holes above the mining holes in a tunnel face.

breaker zone

See: surf zone.


Eng. Fissures in old coal workings. See also: break.

break-even point

a. Production level at which total cost equals revenue.

b. Value or selling price of ore, metal, or mined material that just balances total cost of operations; conversely, maximum unit costs above which there is no profit at given market values.


To start drilling operations with a new bit by rotating the bit slowly under a light load for a short time before full speed and load are applied to the bit.


Size reduction of large particles. Also called cracking.

breaking capacity

The capacity of a switch, circuit breaker, or other similar device to break an electric circuit under certain specified conditions. CF: breaker capacity.

breaking-down rolls

A rolling mill unit used for breaking-down operations; a rolling mill used for reducing sectional dimensions, mainly thickness--of ingots, billets, and other rough, semifinished products--as a preliminary step to subsequent rolling operations.

breaking ground

a. The breaking and loosening of rock as a preparatory step to its loading and removal. See also: excavation.

b. Attrition of an ore deposit by hand, explosive, or mechanical breaking methods to reduce it to pieces of ore suitable for transport and treatment.

breaking in

N. of Eng. See: hewing.

breaking-in shot

a. The first borehole fired in "blasting off the solid" to provide a space into which material from subsequent shots may be thrown. Also called opening shot; buster shot.

b. In blasting a solid face, the first hole or group of holes of a round to be fired simultaneously. See also: burn cut.

breaking lag

As applied to an electric blasting cap, the time elapsing between the bridge wire receiving the firing impulse and the breaking of the circuit.

breaking point

In rock crushers, a deliberate weak link that yields if excessive strain is developed. May be a scarfed toggle, weak cap bolts on a pitman, a shearpin in drive, or a clutch designed to fail at a given load.

breaking prop

Arkansas. One of a row of props of sufficient strength to cause the rock above the coal to break and so limit the area of top brought down by a brushing shot.


Inferior ores arranged ready for crushing.

breaking stress

See: fracture stress.

break in lode

A fault.

break line

a. The line in which the roof of a coal mine is expected to break.

b. The line of complete extraction of coal. c. A line roughly following the rear edges of the pillars that are being drawn or mined. See also: rib line.


Providing a crack indication by striking small slits in the longitudinal direction of a row of drill holes in quarries.


a. To pull drill rods or casings from a borehole and unscrew them at points where they are joined by threaded couplings to form lengths that can be stacked in the drill tripod or derrick.

b. An accidental flow of metal through a hole in a furnace lining.


A row of timbers erected for the purpose of breaking the roof in pillar mining.


a. A passage cut through a pillar to allow the ventilating current to pass from one room to another. Larger than a doghole. Also called room crosscut. Syn: cut-through; crosscut.

b. The point at which a drill bit leaves the rock and enters either a natural or a constructed opening. c. An opening made, either accidentally or deliberately, between two underground workings. d. In an ion-exchange column used in leaching, the arrival of traces of uranium in the final column during the loading (adsorption) cycle. e. See: stenton.

break thrust

A thrust fault that cuts across one limb of a fold.


a. Eng. An excavation commenced from the bottom of a tunnel heading and carried upward, so as to form two interior working faces.

b. Mid. To cut away and remove the floor of an entry or other opening.

breakup value

On exhaustion of an ore deposit or cessation of an exploitation, the value of its onsite buildings, equipment, stockpiles, untouched remnants of ore concentrates, etc.; in foundations of plant; and any other assets still having value apart from their original use.


An offshore structure (such as a mole, wall, or jetty) that, by breaking the force of the waves, protects a harbor, anchorage, beach, or shore area.


a. In a coal mine, a chamber driven in the seam from the gangway, for the extraction of coal; the face of a working.

b. In Italy, a stall in a steep seam from 12 to 18 yd (11 to 16.5 m) wide. The stalls are carried one above another from the lowest level to the rise. c. Leic. To take down or get a buttock (face) of coal end on. d. The end, in unmined rock, of an underground excavation, sometimes called the face; the vertical end surface of a block. See also: before breast. e. A place where anthracite coal is mined; in the soft coal regions, it is called a room. f. The face of a working. g. That part of the bedplate that is back of the crossheads in engines of the Corliss type. h. The side of the hearth containing the taphole in a blast furnace; the rammed material in which the taphole is installed in a cupola.


Pennsylvania. A system of working anthracite coal by bords 10 yd (9.1 m) in width, with narrow pillars 5 yd (4.6 m) wide between them, holed through at certain intervals. The breasts are worked from the dip to the rise. See also: bord-and-pillar.

breast auger

An auger supported by a breastplate against a miner's body. Used for drilling holes in soft coal.

breast board

a. Planking placed between the last set of timbers and the face of a gangway or heading which is in quicksand or loose ground.

b. The timber or boards placed horizontally across the face of an excavation, or heading, to prevent the inflow of gravel or other loose or flowing material.

breast bore

Scot. A borehole put in parallel with the seam, that is made and kept in advance of a working place for the purpose of ascertaining the position of old works, tapping water, letting off gas, etc.

breast coal

The face of the middle or main layer of coal in a composite seam.

breast drill

A small, portable hand drill customarily used by handsetters to drill the holes in bit blanks in which diamonds are to be set. The upper end of the drill is provided with a plate against which the breast of the operator is pressed to force the bit into the work. CF: brace.


In tunnel blasting, holes that parallel the tunnel alignment drilled between the cut and the perimeter holes.

breast eye

Lanc. Opening leading from a working face to the surface.

breast hole

In driving a tunnel, a hole blasted after the bottom cut.


a. N. Staff. A short leading stall, worked at right angles to, and forming the face of, the main level.

b. A wide heading or level. c. Eng. Taking ore from the face or head of a drift. d. In drift mining, breaking down the gravel underground, and retreating towards the crosscut from which the drifts were driven. e. Cumb. A place driven to open out a longwall face.

breast machine

A machine used for undercutting coal in which the main frame and carriage are held stationary by roof jacks while the cutter frame advances into the kerf during the cutting operation. Since cuts do not exceed 44 in (1.1 m) along the face, it is necessary to relocate the machine several times before the entire face can be cut.


A slightly curved iron plate fastened to the end of a coal auger to enable a miner to press the auger forward using body pressure.

breast stoping

A method of stoping employed on veins where the dip is not sufficient for the broken ore to be removed by gravity. The ore remains close to the working face and must be loaded into cars at that point. See also: overhand stoping.

breast timber

A leaning brace from the floor of an excavation to a wall support.

breast wall

A wall designed to withstand the force of a natural bank of earth, such as of timber used to support the face of a tunnel. Syn: jamb wall.


Alternate expansion and contraction of air in breaks that allows fresh oxygen to be drawn in and oxidation to proceed.

breathing apparatus

a. A filter self-rescuer (FSR) is a respiratory protective device that filters ambient air of carbon monoxide, converting it to carbon dioxide. Exhaled air is vented back to ambient. Also called a gas mask. Duration of protection is limited, usually, by water contamination of the chemical bed. Used for escape from underground mines in the event of a fire or explosion. Requirement specified in 30 CFR 75.1714-2(e)(2). Apparatus must be certified as providing at least one hour of respiratory protection. Apparatus available in the United States are the Draeger 910 and the MSA W-65, both certified for one hour.

b. A self-contained self-rescuer (SCSR) is a respiratory protective device that provides breathing gas independent of the ambient atmosphere, containing its own oxygen source. Also called an oxygen self-rescuer. Air is exchanged between the user's lungs and a breathing bag. Oxygen consumed by the user is replaced by the apparatus from its oxygen source, stored either in chemical or compressed form. Carbon dioxide produced by the user is removed by a chemical absorbent in the apparatus breathing circuit. Duration of protection is determined by both quantity of stored oxygen and carbon dioxide absorption capacity. SCSRs differ from rescue breathing apparatus in that the breathing bag is not protected by a rigid cover in order to reduce size and weight. Used for escape from underground mines in the event of a fire or explosion. Requirement specified in 30 CFR 75.1714. Apparatus must be certified as providing at least one hour of respiratory protection. Apparatus available in the United States are the CSE SR-100, the Draeger OXY K plus, the MSA Portal-Pack, the Ocenco EBA 6.5, all certified for one hour. c. A rescue breathing apparatus (RBA) is a respiratory protective device that provides breathing gas independent of the ambient atmosphere, containing its own oxygen source. Air is exchanged between the user's lungs and a breathing bag. Oxygen consumed by the user is replaced by the apparatus from its oxygen source, stored in compressed form in most apparatus. Carbon dioxide produced by the user is removed by a chemical absorbent in the apparatus breathing circuit. Duration of protection is determined by both quantity of stored oxygen and carbon dioxide absorption capacity. RBAs differ from self-contained self-rescuers in that the breathing bag is protected by a rigid cover in order to prevent accidental puncture or tear. Used for entry into underground mines after a fire or explosion in order to reestablish the ventilation system, rescue trapped miners, and put out fires. Requirement specified in 30 CFR 49.1. Apparatus must be certified as providing at least two hours of respiratory protection. Apparatus available in the United States are the Biomarine BioPak 240 and the Draeger BG-174A, both certified for four hours.

breathing cave

a. A cave in which air is alternately blown out and sucked in at the entrance.

b. A narrow part in a passage through which air blows.


A coarse-grained clastic rock, composed of angular broken rock fragments held together by a mineral cement or in a fine-grained matrix; it differs from conglomerate in that the fragments have sharp edges and unworn corners. Breccia may originate as a result of talus accumulation, explosive igneous processes, collapse of rock material, or faulting. Etymol: Italian, broken stones, rubble. Syn: rubblerock. Adj: brecciated. CF: conglomerate; loose ground.


Converted into, characterized by, or resembling a breccia; esp. said of a rock structure marked by an accumulation of angular fragments, or of an ore texture showing mineral fragments without notable rounding.


An orthorhombic mineral, Ca (sub 7) Mg(SiO (sub 4) ) (sub 4) ; pseudohexagonal. CF: larnite.


Mid. Drawing loaded trams downhill underground. Syn: britching.


See: breeze.


a. Coke of small size; the undersize remaining after separating the smallest size of graded coke. Also spelled breese.

b. The dust from coke or coal. c. An indefinite term that usually means clinker, but that may refer to coke breeze. d. Scot. Fine or slack coal.

breeze concrete

A concrete made of 3 parts coke breeze, 1 part sand, and 1 part portland cement. It has poor fire-resisting qualities but it is cheap and nails can be driven into it.

breeze oven

a. An oven for the manufacture of small coke.

b. A furnace designed to consume breeze or coal dust.


Nickel antimonide, NiSb. See also: niccolite.


See: brimstone.

Breton pan

Large steel mortar in which a heavy steel pestle rolls. Once used in grinding and amalgamation of gold ores.

brettice cloth

A variation of brattice cloth. See also: brattice cloth.

brettis way

Derb. A road in a coal mine, supported by brattices built on each side after the coal has been worked out. See also: brattice.


A ferroan variety of magnesite used in the manufacture of magnesia bricks.


A monoclinic mineral, (Sr,Ba,Ca)Al (sub 2) Si (sub 6) O (sub 16) .5H (sub 2) O ; zeolite group.


Liquid plus vapor CO (sub 2) in cavities in minerals; e.g., quartz, topaz, and chrysoberyl. The meniscus vanishes under the warmth of the hand.

Brewster's law

a. The index of refraction of a crystalline substance is equal to the tangent of its angle of polarization.

b. In optics, where light is reflected from a smooth, transparent, nonconducting surface, it is plane polarized parallel to the reflecting surface. The angle of incidence for maximum polarization is that angle whose tangent is the index of refraction of the reflecting substance. This angle is also called the "Brewster angle."

brick clay

An impure clay, containing iron and other ingredients. In industry the term is applied to any clay, loam, or earth suitable for the manufacture of bricks or coarse pottery. Syn: brick earth.

brick coal

Eng. Small, dirty coal suitable for brick kilns and similar purposes.

brick earth

Earth, clay, or loam suitable for making bricks; specif. a fine-grained brownish deposit consisting of quartz and flint sand mixed with ferruginous clay; found on river terraces as a result of reworking by water of windblown material, such as that overlying the gravels on certain terraces of the Thames River in England. Syn: brick clay.

brick fuel

In Wales, patent fuel. See also: briquette.


The walling or casing of a shaft.

bricking curb

A curb set in a circular shaft to support the brick walling. See also: curb.

bricking scaffold

A staging or platform suspended in a sinking shaft on which masons stand when building brick walling. Syn: walling scaffold.

brick walling

A permanent support for circular shafts. On reaching the rockhead, a firm ledge is prepared to receive the first bricking curb or ring. The curb is fixed correctly with reference to the centerline of the shaft. The bricks are then built upwards from the curb, the space behind being firmly packed to the rock sides with bricks and mortar. Concrete is replacing brickwork as a shaft lining. See also: lining; permanent shaft support.


Staff. A contrivance used in coal mining to prevent cars from overturning upon steep inclined planes having a rise of 1 ft in 3 ft or 4 ft (1 m in 3 m or 4 m).

bride cake

A black, highly carbonaceous slickensided shale with Carbonicola shells, in the Adwalton stone or Flockton thick coal; also, dirty smudgy coal in the roof of the Stanley Main in the Snydale-don Pedro area. Syn: bright cake.


a. A rock fragment, cavings, or other obstruction that lodges (either accidentally or intentionally) part way down in a drill hole (such as in an oil well).

b. Debris that plugs a borehole at a point above the bottom. Between the underside of the bridge and the bottom of the drill hole, the borehole is free of debris. c. To deliberately plug a borehole at a point some distance above its bottom. d. To form a bridge in a drill hole. e. In a cave, a solutional remnant of rock that spans a passage from wall to wall. f. A device to measure the resistance of a wire or other conductor forming a part of an electric circuit. g. A piece of timber held above the cap of a set by blocks and used to facilitate the driving of spiling in soft or running ground. h. Refers to the overburden used for spanning the natural gap between the highwall and the spoil, when such is required to establish a temporary machine surface standing area closer to the disposal area than that provided by the virgin ground. i. In an electric blasting cap, the wire that is heated by electric current so as to ignite the charge. j. Sometimes, the shunt connection between the cap wires. k. A plankway or elevator used in ironworking to convey fuel or ore to the mouth of a furnace. l. A refractory bar, or member, or fire clay placed across the surface of the batch in a tank furnace near the working end to hold back the scum, or gall. m. The structure formed by the end walls of the adjacent melter and refiner compartments of a tank and the covers spanning the gap between the end walls. n. See: air crossing.

bridge break

The time that elapses between the application of current and the fusion of the bridge wire when using instantaneous blasting caps.

bridge conveyor

A conveyor that is supported at one end by a loading unit and at the other end in such a way as to permit changes in the position of either end without interrupting the operation of the loading unit.


A borehole plugged by debris lodged at some point above the bottom of a hole. The hole may be bridged deliberately by introducing foreign material into the hole or accidentally by rock fragments sloughing off the sidewalls of the borehole.

bridge over

Collapse of a well bore around the drill stem.

bridge the hole

Deliberate plugging of a borehole at a point some distance above the bottom by introduction of some type of foreign material or a plug. See also: bridge.

bridge tramway

Consists of two steel bridge trusses braced together so as to form between them a runway on which a bucket-carrying trolley runs.

bridge wall

A low separating wall, usually made of firebrick, in a furnace.


A resistance wire connecting the ends of the leg wire inside an electric detonator and which is embedded in the ignition charge of the detonator.


a. In crushing practice, the obstruction of the receiving opening by two or more pieces wedged together, each of which could easily pass through.

b. Formation of arches of keyed or jammed particles across the direction of flow (of rock through apertures or of small particles through filter pores). c. Arching of the charge across the shaft in a blast furnace or cupola. d. Premature solidification of metal across a mold section before the metal below or beyond solidifies. e. Solidification of slag within the cupola at or just above the tuyeres. f. Welding or mechanical locking of the charge in a downfeed melting or smelting furnace. g. Closing of a section of a drill hole by loose blocks of rock or by squeezing of plastic shale, etc.

Bridgman sampler

A mechanical device that automatically selects two samples as the ore passes through.

bridle bar

See: bridle rod.

bridle cable

An anchor cable that is at right angles to the line of pull.

bridle chain

a. One of the chains used for supporting a cage from the winding rope.

b. One of the safety chains used to support the cage if the shackle should break or to protect a train of cars on a slope should the shackle or drawbar fail.

bridle hitch

A connection between a bridle cable and a cable or sheave block.

bridle rod

A steel tie bar used to join the ends of two point rails to hold them to gage in the proper position. Syn: bridle bar.


N. of Eng. A beam or girder fixed across a shaft top.

Briggs clinophone

An instrument used in measuring borehole deviation which transmits electrical signals, communicating to the surface the position of a plumb bob fitted with a needle relative to four electrodes arranged N.,S.,E., and W.--the needle and electrodes being immersed in the electrolyte. Signals are matched with a similar arrangement of needle and electrodes at the surface, and the needle then indicates the deviation and the direction of deviation.

Briggs equalizer

This consists of a head harness, mouthpiece, and noseclip, corrugated breathing tube, Briggs equalizing device, 120 ft (36.58 m) of reinforced air tubes, and a strainer and spike. It has neither bellows nor rotary blower but depends entirely on the action of the equalizer for comfortabIe respiration. The resistance to breathing is so low that reasonably hard work can be done by the wearer over a period of 2 h or more. The air supply tube is attached to the waist by a strong leather body belt.

bright attritus

A field term to denote the degree of luster of attrital coal compared with the brilliant luster of associated vitrain. CF: dull attritus.

bright cake

See: bride cake.

bright coal

a. A type of banded coal defined microscopically as consisting of more than 5% of anthraxylon and less than 20% of opaque matter; banded coal in which translucent matter predominates. Bright coal corresponds to the microlithotypes vitrite and clarite and in part to duroclarite and vitrinerite. CF: dull coal. Syn: brights.

b. The constituent of banded coal that is of a jet black, pitchy appearance, more compact than dull coal, and breaking with a conchoidal fracture when viewed macroscopically, and that in thin section always shows preserved cell structure of woody plant tissue, either of stem, branch, or root. Same as anthraxylon. c. A coal composed of anthraxylon and attritus, in which the translucent cell-wall degradation matter or translucent humic matter predominates. d. A type of banded coal containing from 100% to 81% pure bright ingredients (vitrain, clarain, and fusain), the remainder consisting of clarodurain and durain.

bright head

a. York. A smooth parting or joint in coal; a plane of cleavage.

b. The principal cleat in coal.


The candlepower of a light source divided by the area of the source, and expressed in candles per square inch or candles per square foot.

brightness meter

Visual-type portable photometer operated by visual comparison of brightness. So named because it can be calibrated to indicate the photometric brightness of the object viewed in the sighting telescope.


a. Coal that reflects a large part of incident light, either in a definite beam or by scattering. Two kinds of bright coal are distinguished: vitrain, which reflects an incident beam in a definite direction and consequently appears light or dark according to whether the beam is or is not reflected into the eye; and clarain, which scatters the light and shows a silky luster at whatever angle it is viewed.

b. A commercial term for the larger sizes of bright coal.

bright sulfur

Crude sulfur free of discoloring impurities and bright yellow in color.


A common name for sulfur. Syn: brenston.


a. Water saturated or strongly impregnated with common salt.

b. Sea water containing a higher concentration of dissolved salt than that of the ordinary ocean. CF: artificial brine.

brine field

A section of land under which quantities of rock salt or natural brine of usable strength have been discovered and a well, or any number of wells, has been bored for raising the brine.

Brinell hardness test

A test for determining the hardness of a material by forcing a hard steel or carbide ball of specified diameter into it under a specified load. The result is expressed as the Brinell hardness number, which is the value obtained by dividing the applied load in kilograms by the surface area of the resulting impression in square millimeters. CF: Vickers hardness test.

Brinell hardness tester

a. In heat treating, one who determines the hardness of pieces of metal by the Brinell hardness test. Also called Brinell operator.

b. The machine or instrument used to determine hardness.

brine pit

A salt well, or an opening at the mouth of a salt spring, from which water is taken to be evaporated for making salt.

brine well

A cased drill hole penetrating a salt formation through which water is introduced and brine pumped to the surface.

bring in

Can. Develop a mine from prospect stage.


A block of compressed coal dust, used as fuel; also, a slab or block of artificial stone. Syn: brick fuel; coalette; eggette. Also called boulet; carbonet. Also spelled briquet. See also: solid smokeless fuel.

Briska detonator

A process by which coke breeze, coal dust, iron ore, or any other pulverized mineral is bound together into briquettes, under pressure, with or without a binding agent such as asphalt, and thus made conveniently available for further processing or for commercial markets. Y� ��� p�� ܟ� � � g�DICTIONARY TERMS:Briska detonator An aluminum tube containing a main An aluminum tube containing a main charge of tetryl (tetranitromethylaniline). On top of this are initiating charges of lead azide and lead styphnate, which are more sensitive than the tetryl. A safety fuse fitted into an open space at the top is used to set off the detonator. Syn: aluminum detonator.

Britannia cell

In mineral processing, a pneumatic flotation cell 7 to 9 ft (2.1 to 2.7 m) deep. See also: southwestern cell.


Scot. See: breeching.

British equivalent temperature

See: equivalent temperature.

British thermal unit

Heat needed to raise 1 lb (0.45 kg) of water 1 degrees F (5/9 degrees C) (equal to 252 cal or 1,054 J). Symbol, Btu. CF: heat unit.

brittle material

A nonductile material that fails catastrophically under dynamic loading conditions. Ceramics are an example of a class of brittle materials.

brittle mica

Group of micas having brittle laminae. Chief member is chloritoid, a basic silicate of aluminum, iron, and magnesium, Fe (super 2+) ,Mg,Mn) (sub 2) Al (sub 4) Si (sub 2) O (sub 10) (OH) (sub 4) . See also: mica; margarite.


a. Of minerals, proneness to fracture under low stress. A quality affecting behavior during comminution of ore, whereby one species fractures more readily than others in the material being crushed. See also: toughness.

b. The quality of a material that leads to crack propagation without appreciable plastic deformation.

brittle silver ore

See: stephanite.


a. To restore the diameter of a borehole by reaming.

b. To break down the walls between two contiguous drill holes. c. A sharp-pointed chisel, used for rough dressing stone. d. The perpendicular grooves machined into the bit mold in which inside and outside gage stones are set.


a. Trimming or straightening a mine working.

b. A method of rock excavation employed where it is important that the adjacent rock formation should not be shattered by explosive. A line of closely spaced holes is drilled along the required line of breakage. The rock between the holes is knocked out with a broach and removed with the aid of wedges. See also: channeler. c. Removing metal stock from a workpiece with a broach.

broaching bit

A tool used to restore the dimensions of a borehole that has been contracted by the swelling of the marl or clay walls; also used to break down the intervening rock between two contiguous drill holes. A reamer.

broad coke oven

A special design of oven, used mainly for coking certain grades of coal.


Eng. A main working.

broad lode

Where two or more mining claims longitudinally bisect or divide the apex of a vein, the senior claim takes the entire width of the vein on its dip, if it is in other respects so located as to give the right to pursue the vein downward outside of the sideline. In other words, a broad lode bisected by the division sidelines between two mining claims belongs to the claim having the prior location. The term lode has become extensively used in the classification of ore deposits that are not comprehended by the definition of a vein. Such an occurrence is called a broad lode or zone. See also: broad vein.

broadside shooting

A type of refraction seismic shooting used to determine the structure across the strike. The broadside lines are ordinarily laid out in conjunction with the standard-type profiles that run along the strike. The shot points and detector spreads are laid out along parallel lines, which are generally across the strike. The distance between each line of shots and the receiving line is chosen so that it will always be greater than the double offset distance for the refractor being followed. Generally the distance should be only slightly greater so that the primary refracted event will be received as a second arrival. When this spacing is used, the refracting point associated with the shot will be very close to that associated with the detector, and each delay time will be approx. half the intercept time. A single depth point (based on half the intercept time) is then plotted midway between shot and receiver. All depth points are thus placed along the "control lines" that are located halfway between the shooting line and the receiving line.


A paving slab, so called because it is raised broad and thin from the quarries, not more than 2 to 3 in (5.08 to 7.62 cm) thick.

broad vein

Where a broad vein apexes so that the boundary line between two claims splits the apex, the extralateral rights go to the senior locator, who takes the entire width of the vein on the dip; i.e., a broad lode that is bisected by the division side line between two mining claims belongs to the claim having the prior location. See also: broad lode.


A monoclinic mineral, Cu (sub 4) (SO (sub 4) )(OH) (sub 6) ; has one good cleavage; occurs in the oxidation zone of copper sulfide deposits; a source of copper. Formerly called blanchardite, kamarezite. Syn: waringtonite.


A hexagonal mineral, (Ca,Th,Ce)(PO (sub 4) ).H (sub 2) O ; rhabdophane group.


A thorian variety of uraninite. Also spelled broggerite.


a. A variety of asphalt from Peru.

b. A variety of anthraxolite.


An old Cornish mining term referring to a collection of loose rock fragments usually discolored by oxidation, and indicating the presence of a mineral vein beneath the outcrop or gossan. Also spelled bryle; broyl.

broken charge

A charge of explosive in a drill hole divided into two or more parts that are separated by stemming.

broken coal

In anthracite only; coal that is small enough to pass through a 3-3/8- to 4-in (8.57- to 10.16-cm) square aperture, but too large to pass through a 2-3/4-in or 2-1/2-in (6.99-cm or 6.35-cm) mesh. Smaller than steamboat, and larger than egg coal. See also: anthracite coal sizes.

broken ground

a. A shattered rock formation or a formation crisscrossed with numerous, closely spaced, uncemented joints and cracks. CF: loose ground; breccia.

b. Rock or mineral formations fragmented by blasting with explosives, such as the broken material in a shrinkage stope. Syn: broken rock.

broken rock

See: broken ground.


a. Eng. The removal or extraction of pillars previously formed in bord and pillar working. In Durham and Northumberland, the terms robbery and robbing pillars imply incomplete extraction of the pillars.

b. Robbery. c. Robbing pillars.

broken stone

a. A diamond that has been shattered in use, or lost a portion of its size by cleaving.

b. See: crushed stone.

broken working

The working away or removal of blocks or pillars of coal formed by whole workings. See also: working the broken.


An isometric mineral, 4[AgBr] ; yellow, in surface oxidation deposits of silver ores in arid climates. Formerly called bromyrite. CF: iodargyrite.


A beryllium oxide with dihexagonal-pyramidal crystals from Langban, Sweden. See: beryllium oxide.


A member of the halogen group of elements and the only liquid nonmetallic element. A heavy, reddish-brown liquid that volatilizes readily at room temperature to a poisonous, red vapor with a strong disagreeable odor. Symbol, Br. Obtained from natural brines from wells; little bromine is extracted today from seawater. Used in antiknock gasoline, fumigants, flameproofing agents, water purification compounds, dyes, medicinals, and sanitizers.


An alternate spelling of bromyrite. See also: bromargyrite.


A former name for alstonite.

bromocyanide process

Recovering values from refractory or special gold ores, in which cyanogen bromide (CNBr), or a chemical mixture forming it, is used for treating the ore.


A colorless, heavy liquid; CHBr (sub 3) ; odor and taste similar to those of chloroform; sp gr, 2.8887. Used in mineralogic analysis and in assaying. CF: methylene iodide; Clerici solution; Sonstadt solution. Syn: methenyl tribromide; tribromomethane.


A former name for bromargyrite.


A lead-silver sulfantimonide with 26.2% silver, some of which is apparently diaphorite and some canfieldite. Also spelled brongniartite.


An alloy composed mainly of copper and tin. Various other elements may be added in small amounts for certain specific purposes. A number of copper alloys are referred to as bronzes, although they contain no tin. The American Society for Testing and Materials has classified all copper-based alloys on a basis of composition ranges of the principal alloying elements.

bronze mica

See: phlogopite.


a. A mineral consisting of a ferriferous variety of enstatite, often having a luster like that of bronze; (Mg,Fe (super +2) ) (sub 2) Si (sub 2) O (sub 6) ; orthorhombic.

b. It is often used as a prefix to the names of rocks containing the mineral. Rocks of the gabbro family are the most common ones having the prefix. c. A name for an orthopyroxene between enstatite and hypersthene in composition; brown or green; commonly has a bronzelike or pearly metallic luster.


A pyroxenite composed almost entirely of bronzite.


a. Impurities as extracted with ore.

b. Corn. The heavier kinds of waste in tin and copper ores. A mixture of tin and copper ore.

Brookfield viscometer

An electrically operated, rotating-cylinder viscometer in which the drag is recorded directly on a dial; it has been used in the testing of vitreous-enamel slips.


An orthorhombic mineral, 8[TiO (sub 2) ] ; trimorphous with anatase and rutile; a common accessory mineral in igneous and metamorphic rocks, and placers. See: titanium dioxide.


The crushing and spreading of the head of a timber pile not fitted with a driving band when driven into hard ground.


Derb. A sort of coarse stopping, made of small boughs of trees, and placed in back of shaft timbers to prevent rock from falling.


a. Lanc. An underground roadway leading to a working place, driven either to the rise or to the dip.

b. A low place in the roof of a mine, giving insufficient headroom. c. A fault plane. d. Top of a mine shaft. Also called pit brow. e. The projecting upper part or margin of a steep slope just below the crest; the edge of the top of a hill or mountain, or the place at which a gentle slope becomes abrupt. See also: apex.

brow bar

Mid. A massive curb or beam of timber fixed in the wall of the shaft across the top of an inset or station. Also called browpiece.

brow bin

An ore bin made by cutting away the floor of the station close to the shaft.

Brown agitator

See: Pachuca tank.

brown clay

a. York. Hessle boulder clay.

b. See: red clay.

brown coal

a. A low-rank coal which is brown or brownish-black, but rarely black. It commonly retains the structures of the original wood. It is high in moisture, low in heat value, and checks badly upon drying.

b. A light-brown to seal-brown substance intermediate between peat and bituminous coal; usually regarded as a variety of lignite, other varieties being darker or black. It may be distinguished from peat by three rough criteria: (1) many tissues and fibers can be recognized in peat, but only a few fibers or none in brown coal; (2) water can be squeezed out of fresh peat by manual pressure, but not from brown coal; and (3) peat can be cut, but brown coal cannot. Actually, there is no sharp distinction between peat and coal. Some have attempted to assign it a higher rank by defining lignite as containing at least 20% water, brown coal between 10% and 20% water, and bituminous coal less than 10% water. c. A type of low-rank coal intermediate between bituminous coal and peat, and comparatively high in water content. In English-speaking countries, the terms "brown coal" and "lignite" are synonymous; in Germany and other parts of Europe, brown coal is restricted to megascopically compact structural varieties, and lignite is restricted to individual pieces of wood enclosed in brown coal. It may be subdivided into low-grade brown coal, consisting of visible vegetable remains, and high-grade brown coal, a compact, homogeneous, and tough rock. Syn: braunkohle. d. Coal of the lowest rank, soft and friable, and having a high inherent moisture content. e. Unconsolidated lignitic coal having less than 8,300 Btu (8.76 MJ), (moist, mineral-matter-free).

brown-coal gel

See: dopplerite.

brown gummite

See: clarkeite.

brown hematite

A misnomer; the mineral bearing this name is limonite, a hydrous mixture of minerals, whereas true hematite is an anhydrous oxide mineral. Syn: limonite; brown iron ore. CF: red hematite.

Brown horseshoe furnace

An annular turret-type furnace for calcining sulfide ores.

brown iron ore

a. Its approximate formula is 2Fe (sub 2) O (sub 3) .3H (sub 2) O , equivalent to about 59.8% iron. Probably a mixture of hydrous oxides. See also: bog ore.

b. See: limonite; brown hematite.

brown ironstone clay

See: limonite.

brown matter

Brown matter is found in varying amounts in the attrital matter of all splint and semisplint coals; it is occasionally present in the attritus of bright coals. It consists of cell-wall degradation matter and the contents of cells, which in thin sections are brown and semitranslucent. The term has no exact equivalent in the Stopes-Heerlen nomenclature. Constituents with a reflectance between that of vitrinite and fusinite may correspond in part to brown matter. Some brown matter is identical with semifusinite and massive micrinite.

brown mica

See: phlogopite.

brown millerite

See: celite.


A mineral, Ca (sub 2) (Al,Fe) (sub 2) O (sub 5) ; a constituent of Portland cement. Syn: celite.

Brown muffle furnace

A mechanically raked, roasting, straight-line-type furnace with a series of longitudinal combustion flues placed under the hearth.

brown ocher

See: limonite.

Brown-O'Hara furnace

A long, horizontal, double-hearth furnace for the treatment of lead ores.

Brown panel system

a. See: pillar-and-breast.

b. Coal mining by long rooms opened on the upper side of the gangway. The breasts are usually 5 to 12 yd (4.6 to 11.0 m) wide and are separated by pillars (solid walls of coal broken by crossheadings for ventilation) 5 to 12 yd thick. The pillars are robbed by mining from them until the roof comes down and prevents further working. Syn: block system of stoping and filling.

brown rock

Tenn. Dark brown to black phosphorite resulting from the weathering of phosphatic limestone. See also: phosphorite.

brown spar

Any light-colored crystalline carbonate mineral that is colored brown by the presence of iron; e.g., ankerite, dolomite, magnesite, or siderite.


A brown or reddish-brown sandstone with grains generally coated with iron oxide; specif. a dark, reddish-brown, ferruginous quartz sandstone of Triassic age.

Brown tank

A cylindrical tank or vat, tall in proportion to its diameter, with the bottom ending in a 60 degrees cone. Within the tank is a hollow column extending from the bottom to within about 8 in (20.32 cm) from the top. The apparatus works on the airlift principle, the aerated pulp in the tube flowing upward and discharging at the top, while more pulp flows in at the bottom to take its place. Syn: Brown agitator; Pachuca tank.

brown tongs

A long-handled, plierlike device similar to a certain type of blacksmith tongs used to handle wash or drill rods in place of a safety clamp in shallow borehole drilling. Also called adjustable pipe tongs; extension tongs; lowering tongs.

brown umber

A brown earthy variety of limonite. See also: limonite.


A heavy, upright timber used for underpinning in opening a station for a level in a mine. See also: brow bar.


Ore imperfectly smelted, mixed with cinder and clay.


Lanc. An inclined roadway driven to the rise. Also called brow; up-brow.


a. A trigonal mineral, Mg(OH) (sub 2) ; brucite group; perfect basal cleavage; an alteration product of periclase in contact-metamorphosed limestone; a magnesia refractory raw material.

b. The mineral group amakinite, brucite, pyrochroite, and theophrastite.

Bruckner cylinder

Pac. A form of revolving roasting furnace. See also: Bruckner furnace.

Bruckner furnace

Horizontal cylindrical furnace revolving on end trunnions. See also: Bruckner cylinder.


A Canadian term used to describe a windfall of dead trees and brush. Syn: slash.

Brunauer, Emmett, and Teller method

A procedure for the determination of the total surface area of a powder or of a porous solid by measurement of the volume of gas (usually N (sub 2) ) adsorbed on the surface of a known weight of the sample. The mathematical basis of the method was developed by S. Brunauer, P. H. Emmett, and E. Teller--hence the usual name, B.E.T. method.

Brunton compass

A compact pocket instrument that consists of an ordinary compass, folding open sights, a mirror, and a rectangular spirit-level clinometer, which can be used in the hand or on a staff or light rod for reading horizontal and vertical angles, for leveling, and for reading the magnetic bearing of a line. It is used in sketching mine workings, and in preliminary topographic and geologic surveys on the surface, e.g., in determining elevations, stratigraphic thickness, and strike and dip. Syn: pocket transit.

Brunton sampler

A mechanical sampling device that automatically selects 1/625 part of the ore passing through the sampler, by means of an oscillating deflector placed in a falling stream of the ore.


a. To remove rock from the roof or floor of an opening to increase the height of working (coal mines). See also: brushing.

b. In a coal mine, a road through the goaf, gob, or worked-out areas packed with waste. c. To clean up fine coal from the floor. d. Forest of Dean. A rich brown hematite. e. Mixed load of large and small coal into a colliery tub. f. Mid. To mix gas with air in a mine by buffeting it with a jacket. g. To rip; to enlarge. h. To remove bisque in a definite pattern by means of a brush. See also: bolt-hole brush.

brush cleaner

A device consisting of bristles set in a suitable backing used for cleaning a conveyor belt. It is usually of the rotary type.

brush discharge

In high-intensity electrical fields, discharge from sharp points along a conductor. Electricity concentrates at these points and charges ambient molecules of air, which are then repelled, carrying away charge. The phenomenon is exploited in mineral processing in high-tension separation.

brush hook

A short, stout, heavy hooked blade with a sharpened iron edge, attached to an axe handle; typically used by surveyors for cutting brush.


a. Scot. That part of the roof or floor of a seam removed to form roadways.

b. Digging up the bottom or taking down the top of an entry or room, where the seam of coal is too thin or shallow for the purpose of admitting cars. See also: brush. c. Cutting or blasting down the roof of a coal seam. d. Ripping; normally enlarging a road by taking down the roof, but extended to sides and floor as well. Also called canch. e. Removal of dry enamel by brushing through a stencil or along an edge to produce a design or edging.

brushing bed

Scot. The stratum brushed or rippled. See also: brush.

brushing shot

a. A charge fired in the air of a mine to blow out obnoxious gases or to start an air current.

b. A shot so placed as to remove a portion of the roof to increase the height of a haulageway. See also: brush.


A monoclinic mineral, CaHPO (sub 4) .2H (sub 2) O ; generally massive or in slender crystals. Syn: metabrushite.

brush rake

A rake blade having a high top and light construction.

brush treatment

A method of treating mine timber in which the timber is painted with a preservative or is merely dipped into a tank of preservative. Preservatives used are creosote, zinc chloride, sodium fluoride, and other chemicals. See also: timber preservation.


Mid. Lump of coal weighing about 1 lb.


See: broil.

bubble chamber

A device that marks the paths of charged particles by photographing the train of bubbles they produce as they move through certain superheated liquids. See also: cloud chamber; spark chamber.

bubble pickup

Method of testing small grains of minerals to ascertain their response to flotation collector agents. A bubble of air is pressed down on particles under water, and then raised and examined to find whether it has lifted any grains. This is often done by using a single bubble device for determining fundamental aspects of the mineral-bubble interaction.

bubble pipe

Tube inserted in pulp at regulated depth, through which compressed air is gently bubbled. The air pressure indicates the pulp density and provides a means of control.

bubble pulse

A pulsation attributable to the bubble produced by a seismic charge fired in deep water. The bubble pulsates several times with a period proportional to the cube root of the charge, each oscillation producing an identical unwanted seismic effect.


Air introduced near the bottom of a flotation cell containing pulped ore forms coursing bubbles, which rise through the liquid and emerge as mineralized bubbles forming a semistable froth column. This depends for its continuity partly on the surface-active reagents borne by the mineral in the air-water interphase of each bubble and partly on the aid of frothing reagents.


A resin resembling amber but insoluble in alcohol and yielding no succinic acid.

Buchner funnel

A porcelain filter shaped to support filter paper on a flat perforated disk.


a. A large quartz reef in which there is little or no gold. See also: bull quartz.

b. To push coal down a chute toward a mine car. c. To break up or pulverize, as to buck ore samples. d. To bring or carry, as to buck water.

bucker helper

One who breaks ore.


a. See: bailer; calyx.

b. Tubular container equipped with auger or other-type cutting edges used to make borings in earthy or soft formation by rotary methods. c. An open-top can, equipped with a bail, used to hoist broken rock or water and to lower supplies and equipment to workers in a mine shaft or other underground opening. d. One of the conveying units on a bucket conveyor that lifts the material from a boot or bin when passing over the lower sprocket and is dumped on passing over the upper sprocket. The bucket is often made of perforated metal so that water entrapped will pass through the perforations and back to the boot. e. A part of an excavator that digs, lifts, and carries dirt. f. The dipper or scoop at the end of the arm of a bucket dredge.

bucket auger

A short helical auger incorporating a steel tube to help hold the cuttings on the auger during withdrawal from the drill hole. See also: auger.

bucket conveyor

A conveyor consisting of a continuous line of buckets attached by pivots to two endless roller chains running on tracks and driven by sprockets. The buckets are so pivoted that they remain in an upright position at all times except when tilted into a dumping position by a cam or other device placed at any required position on the track. See also: bucket elevator; gravity-discharge conveyor elevator; pivoted-bucket conveyor.

bucket dredge

A dredge having two pontoons, between which passes a chain of digging buckets. These buckets excavate material at the bottom of the pond (paddock) in which the dredge floats, and deposit it in concentrating devices on the decks.

bucket drill

Originally developed as an aid in making excavations for cesspools and septic tanks; now used mostly in drilling holes for concrete piers on construction jobs. Also called bucket drilling.

bucket elevator

a. An appliance for elevating material, consisting of steel buckets fastened to an endless belt or chain. It is usually set at steep angles, around 70 degrees . The load is picked up by discharge from a chute or by a dredging action in a boot. Its best application is in a plant where space is restricted and the size of the material is less than 2 in (5.1 cm). Syn: chain elevator.

b. See also: centrifugal discharge bucket elevator; continuous-bucket elevator; double-leg bucket elevator; elevator; gravity-discharge conveyor elevator; internal-discharge bucket elevator; positive-discharge bucket elevator; pivoted-bucket conveyor; grit collector.

bucket elevator belt

A belt fabricated for bucket elevator use, to which an elevator bucket is attached.

bucket factor

See: fill factor.

bucket gate

See: bin gate.

bucket-ladder dredge

a. A dredge with a digging mechanism consisting of a ladderlike truss on the periphery of which is attached an endless chain that rides on sprocket wheels and on which buckets are attached.

b. A mechanical dredge that uses a chain of heavy buckets rotating over the dredging arm or ladder to excavate and lift material to the dredging platform. Syn: bucket-line dredge; ladder-bucket dredge. See also: dredger.

bucket-ladder excavator

A mechanical excavator working on the same principle as a bucket-ladder dredge, but adapted for use on land. See also: trench excavator.

bucket lift

The discharge pipe of a lifting pump in a mine.

bucket line

An endless line of digging buckets on a dredger or on a bucket elevator.

bucket-line dredge

See: bucket-ladder dredge.

bucket loader

a. A form of portable, self-feeding, inclined bucket elevator for loading bulk materials into cars, trucks, or other conveyors. See also: bucket elevator; portable conveyor.

b. A machine having a digging and gathering rotor and a set of chain-mounted buckets to elevate the material to a dumping point.

bucket pump

a. An iron or wooden receptacle for hoisting ore, or for raising rock in shaft sinking.

b. A reciprocating lift pump formerly much used in shafts and sinkings.

bucket rig

See: rotary bucket drill.

bucket sheave

A pulley attached to a shovel bucket, through which the hoist or drag cable is reeved.

bucket temperature

The surface temperature of the sea as measured by a bucket thermometer or by immersing a surface thermometer in a freshly drawn bucket of water.

bucket thermometer

A water-temperature thermometer provided with an insulated container around the bulb. It is lowered into the sea on a line until it has had time to reach the temperature of the surface water, then withdrawn and read. The insulated water surrounding the bulb preserves the temperature reading and is available as a salinity sample.

bucket tripper

A device that tilts or turns the buckets of a pivoted bucket conveyor, causing them to discharge. It may be fixed or movable.

bucket-wheel dredge

An hydraulic cutter dredge that uses a bucket wheel excavator in place of the traditional rotary cutter. The bucket wheel is characterized by its high cutting torque in both directions and by a positive feed of the excavated material into the mouth of the dredge pipe.

bucket-wheel excavator

A continuous digging machine originally designed and used in large-scale stripping and mining of brown coal deposits in eastern Germany. Its digging mechanism is essentially a boom on which is mounted a rotating vertical wheel having buckets on its periphery. As the rotating wheel is pressed into the material to be dug, the buckets cut, gather, and discharge the material onto a conveyor belt where it is moved to the mined materials transport system.

bucking hammer

A rectangular piece of cast iron 5 to 6 in (12.7 to 15.24 cm) across, usually rounded fore and aft with an eye on the back and with a wooden handle; used for grinding ore on a cast-iron bucking board.

bucking iron

An iron plate on which ore is ground by hand by means of a bucking hammer. Used extensively for the final reduction of ore samples for assaying. See also: muller.


a. A black variety of epidote containing iron and having nearly symmetrical crystals.

b. A former name for allanite.


a. A bend in a piece of drill-stem equipment induced by excessive feed pressure.

b. Deformation of component members of a drill derrick, tripod, or mast, caused by attempting to hoist too heavy a load or by applying excessive strain when pulling on stuck casing, etc.

buckling length

The length of drill rod that will withstand flexure or bending when subjected to a specific feed pressure or compressional load.

buckling load

The maximum load that can be imposed on a string of drill rods, casing, or pipe, or on a drill tripod, derrick, or mast without the string buckling; also, a part being bent or buckled.

buck quartz

See: bull quartz.

buck reef

A barren vein.

buckshot cinder

Cinder from an iron blast furnace, containing grains of iron.

buck up

a. To screw two threaded members, such as drill rods, together tightly.

b. To shore up with lagging; to brace.


Coal size designation, used for anthracite only. Buckwheat is divided into four sizes: No. 1, or buckwheat; No. 2, or rice; No. 3, or barley; No. 4, or barley No. 2 or silt (sometimes also called culm or slush). Buckwheat No. 1 passes through a 1/2-in (12.7-mm) woven wire screen and over a 5/16-in (7.9-mm) woven wire screen, and through a 9/16-in (14.3-mm) round punched plate and over a 3/8-in (9.5-mm) round punched plate. The American Institute of Mechanical Engineers has recommended that buckwheat No. 1 shall pass through 9/16-in holes and over 5/16-in holes, a screen with circular holes being used. See also: anthracite coal sizes.


a. Circular arrangement in which finely divided ore, in water, is delivered from a central point and flows gently to the perimeter. The heaviest and coarsest particles settle, while the lightest overflow. Several variants include concave buddle, with peripheral feed and central discharge; and continuous buddles, as differentiated from those that are periodically stopped and cleaned up.

b. To separate ore from slime or stamp work by means of a buddle.


A shortwall coal cutter designed for light duty on longwall power-loaded faces and for subsidiary developments.

buddy system

In scuba diving, divers with few exceptions should work in pairs. This is probably the greatest single aid toward scuba safety, esp. under unfavorable conditions. The divers should remain in sight of each other. In poor visibility, they should use a buddy line 6 to 10 ft (1.8 to 3.0 m) long.


a. A pile of blasted rock left against or near a face to improve fragmentation and reduce scattering from the next blast.

b. A substance whose purpose is to maintain a constant hydrogen-ion concentration in water solutions, even when acid or alkalies are added.

buffer shooting

See: blanket shooting.


a. A bullet or go-devil. See also: bullet.

b. Syn. for vug and bug hole (slang).

bug dust

a. The fine coal or other material resulting from a boring or cutting of a drill, a mining machine, or even a pick.

b. Fine, dry, dustlike particles of rock ejected from a borehole by a current of pressurized air when compressed air, instead of a liquid, is used as a cuttings removal agent. Syn: cuttings. See also: nickings. c. Fine coal or rock material resulting from dry boring, drilling, or the use of other cutting machines in underground work places.

bug dusting

Removing bug dust from an undercut.


Pennsylvania. Said of coal moved underground in a small car.


a. A four-wheeled steel car used for hauling coal to and from chutes.

b. A mine car of small dimensions, sometimes used in thin beds. c. Slang for a shuttle car. d. See: bug dust.

bug hole

See: vug.

bug light

Slang for a miner's electric cap lamp.


a. A stone disk mill, with an upper horizontal disk rotating above a fixed lower one. Grist is fed centrally and discharged peripherally. Stones are dressed periodically, channels being cut to facilitate passage. Also applied to other rubbing mills; e.g., conical porcelain or steel ones in which a grooved cone rotates in a close fit in a fixed casing. Also spelled: burrmill.

b. A stone mill, consisting of one stationary stone and one revolving stone, for grinding pigment pastes.


a. A siliceous rock suitable for use as millstones; e.g., an open-textured, porous but tough, fine-grained sandstone, or a silicified fossiliferous limestone. In some sandstones, the cement is calcareous. Syn: millstone.

b. A millstone cut from buhrstone. Also spelled burrstone; burstone. Syn: burr.

buhrstone mill

A grinding mill with two horizontal circular stones, one revolving upon the other, such as in an old-fashioned grain mill.

building stone

A general, nongeneric term for any rock suitable for use in construction. Whether igneous, metamorphic, or sedimentary, a building stone is chosen for its properties of durability, attractiveness, and economy. See also: dimension stone.


Brist. Run-of-mine coal in large quantities.

bulk density

a. The weight of an object or material divided by its volume, including the volume of its pore spaces; specif. the weight per unit volume of a soil mass that has been oven-dried to a constant weight at 105 degrees C. CF: apparent density.

b. The ratio of the weight of a collection of discrete particles to the volume that it occupies. c. The weight of a material, on being compacted in a defined way, per unit volume (including voids). d. The weight per unit volume of any material, including water; the weight in pounds per cubic foot (kg/m (super 3) ). See also: apparent density; density; loading weight.

bulk explosives

Explosives not individually packaged in a form usable in the field. Includes ammonium nitrate-fuel oil, slurries, water gels, and other similar blasting agents; often loaded directly into blast holes from a bulk delivery truck.


a. A watertight dam containing some form of door or removable plate. See also: dam.

b. A tight partition of wood, rock, and mud or concrete in mines for protection against gas, fire, and water. c. A masonry diaphragm built across a subaqueous tunnel, where compressed air is used as a precaution, and to prevent the flooding of an entire tunnel in case of an accident. It is usually kept some distance in the rear of the working face and is provided with two air locks; one of them is an emergency lock near the roof. d. A stone, steel, wood, or concrete wall-like structure primarily designed to resist earth or water pressure, such as a retaining wall holding back the ground from sliding into a channel, or a partition preventing water from entering a working area in a mine. e. A timber chock in metal mines. f. The end of a flume, whence water is carried in iron pipes to hydraulic workings. g. A solid crib used to support a very heavy roof. See also: cog; chock. h. A panel of brick of lesser cross-sectional thickness built into a wall for ease of replacement or for entrance to the walled chamber.


a. The increase in volume of a material due to manipulation. Rock bulks upon being excavated; damp sand bulks if loosely deposited, such as by dumping, because the apparent cohesion prevents movement of the soil particles to form a reduced volume.

b. The difference in volume of a given mass of sand or other fine material in moist and dry conditions; it is expressed as a percentage of the volume in a dry condition.

bulking agent

Chemically inert materials for increasing the volume of a composition; e.g., clay. Also called a filler.

bulk mining

A method of mining in which large quantities of low-grade ore are mined without attempt to segregate the high-grade portions. CF: selective mining.

bulk mix

A mass of explosive material prepared for use in bulk form without packaging.

bulk modulus

The number that expresses a material's resistance to elastic changes in volume; e.g., the number of pounds per square inch necessary to cause a specified change in volume. See also: modulus of elasticity; modulus of rigidity.

bulk modulus of elasticity

The ratio of a tensile or compressive stress, triaxial and equal in all directions (e.g., hydrostatic pressure), to the relative change it produces in volume.

bulk oil flotation

a. A flotation process in which large amounts of oil are used.

b. In this process the separation of mineral from gangue is accomplished by virtue of the fact that minerals of metallic luster, such as sulfides, or hydrocarbons, such as coal and graphite, are wetted preferentially by oil in the presence of water and consequently pass into the interface between oil and water, while gangue or rock is wetted by water and remains in the medium. See also: flotation.

bulk oil separation

A concentration process based on selective wetting of minerals by oil in the presence of water and in the absence of air.

bulk pit excavation

Primarily excavation of considerable length as well as of substantial volume or bulk that must be hauled from the site of operations. Also called enbankment digging.

bulk sample

One of the large samples of a few hundredweight or more taken at regular, though widely spaced, intervals. In the case of coal, a car load may be taken at intervals for size analysis and dirt content.

bulk sampling

The taking of large samples, which may consist of large-diameter drill core, the contents of a trench or mine working, or a car or train load of ore material, for metallurgical testing in mine evaluation.

bulk specific gravity

Ratio of the weight in air of a given volume of permeable material (including both permeable and impermeable voids normal to the material) at a stated temperature to the weight in air of an equal volume of distilled water at a stated temperature. Also called specific mass gravity.

bulk strength

The strength per unit volume of an explosive calculated from its weight strength and density. See also: cartridge strength; absolute bulk strength.

bulk volume

A term used relative to the density and volume of a porous solid, such as a refractory brick. It is defined as the volume of the solid material plus the volume of the sealed and open pores present.

bulk wide-area excavation

In this kind of excavation, there is complete access to the site from many directions, and the excavation banks can be sloped flatly on two or more sides. Usually shallower in depth than bulk pit excavations but larger in area. CF: bulk pit excavation.


a. An iron rod used in ramming clay to line a shothole. See also: clay iron.

b. Aust. See: drag; backstay. c. N.S.W. To enlarge the bottom of a drilled hole to increase the explosive charge.

Bullard Dunn Process

Electrolytic method of descaling iron and steel and coating the surface with a protective layer of tin.

bull clam

A bulldozer fitted with a curved bowl hinged to the top of the front of the blade.


a. A type of drill-rod-foot safety clamp built somewhat like a spider and slips, but differing by having the slips or movable jaws attached to, and actuated by, a foot-operated lever.

b. A general term applied to rod and/or casing safety clamps having both fixed and movable serrated jaws that contact and securely grip the rods or casing. c. A fishing tool consisting of a steel body, tapered at the top, on which slide two or more wedge-shaped, serrated-face segments. Lowered into a tubular piece of lost equipment, such as casing, the serrated segments are pushed upward toward the narrow part of the body; when the tool is raised, the segments are forced outward, securely gripping the lost equipment. Also called bulldog spear; casing dog; casing spear. d. To pull or move a drill machine or auxiliary equipment by means of a block and tackle or by power derived from a rope used on the drill cathead or hoist drum. Also called cat; snake.


a. To level or excavate an earth surface by means of a heavy, adjustable steel blade attached to the front end of a tractor or a wheeled vehicle.

b. To reduce broken rock by the use of explosives to a size handy for raising to the surface. See also: adobe charge; mudcap; secondary blasting.


a. In nonmetal mining, a laborer who breaks up large stones with a sledge hammer or pneumatic drill so they will pass through grizzly (grating) in a limestone mine.

b. A horizontal machine, usually mechanical, having two bull gears with eccentric pins, two connecting links to a ram, and dies to perform bending, forming, and punching of narrow plate and bars. c. A cleaning blade that follows the wheel or ladder of a ditching machine. d. A tractor on the front end of which is mounted a vertically curved steel blade held at a fixed distance by arms secured on a pivot or shaft near the horizontal center of the tractor. The blade can be lowered or tilted vertically by cables or hydraulic rams. It is a highly versatile piece of earth excavating and moving equipment esp. useful in land clearing and leveling work, in stripping topsoil, in road and ramp building, and in floor or bench cleanup and gathering operations. Also called dozer.

bulled hole

A quarry blasting hole, the bottom of which has been enlarged or chambered to receive a heavy explosive charge. See also: chambering.


a. A small, lustrous, nearly spherical industrial diamond.

b. A conical-nosed, cylindrical weight, attached to a wire rope or line, either notched or seated to engage and attach itself to the upper end of the inner tube of a wire-line core barrel or other retrievable or retractable device placed in a borehole. Syn: bug; go-devil; overshot. c. A bullet-shaped weight or small explosive charge dropped to explode a charge of nitroglycerin placed in a borehole.

bull gear

a. A toothed driving wheel that is the largest or strongest in the mechanism.

b. A gear or sprocket that is much larger than the others in the same power train.


Trade name for an International (formerly Bucyrus-Erie) angling bulldozer.


Fragments of country rock enclosed in a mineral vein.


The firing of explosive charges in the cracks of loosened rock. The clay stemming is forced around the charge by a bulling bar. See also: bulled hole.

bulling shovel

A triangular, sharp-pointed shovel used in ore dressing. Also called vanning shovel.


a. A concretion found in some types of coal; composed of carbonate or silica stained by brown humic derivatives; often a well-preserved plant structure forms the nucleus. Also called coal ball.

b. Lanc. Nodule of clay ironstone, pyrite, shale, etc., that generally enclose a fossil. c. Refined gold or silver, uncoined, in the shape of bars, ingots, or comparable masses.

bullion bar

Refined gold or silver in the form of bars of convenient sizes and weights for handling and storage.

bullion content

Bullion (gold or silver) weight in a parcel of mineral or metal changing hands. The major value is that of the carrier (e.g., argentiferous lead), but payment is made both for this and for the precious metal.

bull ladle

Usually the largest ladle in a foundry.

bull mica

Large clusters of diversely oriented and partially intergrown crystals of muscovite with a little interstitial albite and quartz.

bullnose bit

A noncoring bit having a convex, half-hemispherical-shaped crown or face. Also called wedge bit; wedge reaming bit; wedging bit. See also: plug bit. CF: taper bit.

bull pup

A worthless mining claim.

bull quartz

White massive quartz, essentially free of accessory minerals and valueless as ore. Syn: bastard quartz; buck quartz.


A nodule of pyrite in roofing slate.

bull's-eye tuyere

A tuyere discharging in the center of a hemispherical plate.

bull shaker

A shaking chute where large coal from the dump is cleaned by hand.

bull wheel

a. The large winding drum on which the drill cable or bull rope of a churn or cable-tool drill is wound.

b. Large sheave at the top of the mineshaft headframe over which the cage- or skip-hoist rope passes. c. An underground sheave wheel; particularly, the wheel around which the tail rope is passed beyond each terminal of a tail-rope haulage system. d. The pulley that rotates the camshaft of a stamp battery.


A developing heading driven to the dip, usually the full dip of the coal seam; worked by rope haulage.


See: springing.


A small boat equipped with a hoist and used for handling dredge lines and anchors.


a. Any dull, hollow sound produced in a coal seam or associated strata as a result of mining operations. See also: outburst; crump; rock bump; rock burst.

b. Sudden failure of the floor or walls of a mine opening, generally accompanied by a loud report and a sharp shock or jar. c. An earth tremor occasioned by a rock failure, when that failure causes no damage to the workings. d. A noise caused by a break in the roof underground. e. The actual movement due to the roof break. f. A sudden floor uplift due to a break in the floor. g. In coal mining, shock due to the movement of coal, floor, or roof strata, with sufficient violence to be heard and to shake the workings. h. Rebound caused by a sudden release of tension on the drill stem when a core breaks or snaps free of the bottom of the borehole. i. A sharp, upward blow applied to the drivepipe, casing, or drill stem with a drive hammer.


a. A worker who pushes loaded cars or cans into a station for the hooker and removes the empties.

b. A device used to loosen the tools when drilling is carried on without jars. c. A fender for lessening the jar caused by the collision of cars or other moving equipment. d. See: catch. e. A machine used for packing molding sand in a flask by repeated jarring or jolting.

bumper block

An impeding device at dumping locations where there is a hazard of vehicle overtravel.

bumper post

Barrier of heavy steel construction anchored at a track ending to stop rolling railroad cars and prevent their being thrown off center or derailed.

bumping table

See: shaking table.

bumping trough

An appliance for handling broken rock in flat mine stopes. A sheet-steel trough is hung from chains and arrested at one end of its swing by a bump stop, so that the ore slides forward.


Sudden, violent expulsion of coal from one or more pillars, accompanied by loud reports and earth tremors. Bumps occur in coal mines where a strong, thick, massive sandstone roof rests directly on the coal with no cushioning layer of shale between. The breaking of this strong roof as the seam is mined causes violent bumps and the crushing and bursting of pillars left for support. There are two distinctive types of bumps: (1) pressure bumps, which appear to be due to the unit loading of a pillar being too great for its bearing strength, and where the coal roof and floor are strong, the pillar is ruptured suddenly and with violence; and (2) shock bumps, which are thought to be due to the breaking of thick, massive, rigid strata somewhere above the coalbed, which causes a great hammerlike blow to be given to the immediate roof, which it transmits as a shock wave to the coal pillar or pillars.

bunched seismometers

Group of seismometers located at short intervals at the same seismometer station and electrically interconnected. Syn: multiple seismometers.


a. An orebody containing small scattered masses of bunches of ore.

b. A mine that is sometimes rich and at other times poor.


Any artificial embankment used to control the flow of water in a river or on irrigated land. The term is applied extensively in India to large low dams and dikes and also to the small ridges between rice fields. Also, an embanked causeway or thoroughfare along a river or the sea.


A vessel for the storage of materials; the lowermost portion is usually constructed in the form of a hopper. Also called bin. See also: surge bunker; underground bunker.

bunker coal

Applied to coal consumed by ocean steamers, tugs, ferryboats, or other steam watercraft. Also called bunkers.

bunker conveyor

A high-capacity conveyor that takes peaks of production from another conveyor and retains and/or discharges the material when production drops. Such a conveyor may be laid under or alongside a trunk belt near its discharge end. The floor of the bunker comprises a slow-moving steel plate conveyor operated by hydraulic or other power. A movable plow plate, situated over the trunk belt, diverts the material sideways into the bunker conveyor. See also: underground bunker.

bunker gate

See: bin gate.

bunkering capacity

The capacity of anything. It may be expressed as a tonnage or as so many hours of normal production. Bunkering capacity may be provided at the surface and at critical points underground.


a. A mass of ore not lying in a regular vein. Also spelled bunny, bonny, bonney.

b. Corn. An isolated body of ore.


See: bunney.


A pistachio-green isometric mineral, NiO, of the periclase group.

Bunsen photometer

A visual photometer in which a simple mirror system enables both sides of the test plate, consisting of a screen of opaque-white paper on which is a grease spot, to be viewed at the same time. That portion of the screen on which the grease lies is translucent to light, so that there is a difference in brightness between the grease spot and the surrounding ungreased paper. When comparing sources, one on either side of the photometric bench, the point of balance is such that, as seen in the mirror, both sides of the screen show equality of contrast between the grease spot and its white surroundings.


a. A steel or timber element in the lining of a rectangular shaft. Buntons may be 6 in by 5 in or 6 in (15.2 cm by 12.7 cm or 15.2 cm) square and extend across the shaft at intervals of 4 ft to 8 ft (1.2 m to 2.4 m). They serve to reinforce the barring and also carry the cage guides. Rolled steel joists are now generally used as buntons. See also: divider; wallplate.

b. A timber placed horizontally across a shaft. It serves to brace the wallplates of the shaft lining and also, by means of planks nailed to them, to form separate compartments for hoisting or ladderways.

bunton racking

Timber pieces used in the support of rectangular shafts. See also: wallplate.

buoyant weight

The apparent weight of a string of drill tools suspended in a liquid-filled borehole. The apparent weight is the weight of the drill string in air less the weight of the liquid displaced by the drill string when suspended in a liquid-filled borehole.


An aurichalcite containing calcium monoxide, probably as a mechanical admixture.


A hexagonal mineral, (Na,Ca) (sub 3) (Sr,Ba,Ce) (sub 3) (CO (sub 3) ) (sub 5) .


a. The distance from the borehole and the nearest free face or distance between boreholes measured perpendicular to the spacing (usually perpendicular to the free face).

b. All types of rock or earthy materials overlying bedrock. See also: cover; mantle; overburden. c. Valueless material overlying ore, esp. that removed by stripping. Frequently called overburden. d. The resistance that an explosive charge must overcome in breaking the rock adjacent to a drill hole in mining. e. The tonnage or cubic yards of rock, ore, or coal that an explosive charge is expected to break. f. The distance between the charge and the free face of the material to be blasted. g. See: line of least resistance. h. The charge of a blast furnace exclusive of the fuel; also, the ratio of the ore to the total charge.

burdening the furnace

Determining the proper proportions of ore, coke, and limestone for a blast furnace charge.


Small coal suitable for furnaces or engines.

Burgers vector

In crystal structures, dislocations locally alter coordination polyhedra with the result that regular polyhedra several atomic diameters distant are offset from their regular positions. The Burgers vector is a measure of that offset, being normal to edge dislocations and parallel to screw dislocations.

buried hill

A hill of resistant older rock over which later sediments were deposited. The overlying sedimentary beds have the form of an anticline as the result of original dip, unequal compaction, etc. The term was first applied to the underlying beds of the Healdton Field, OK.

buried outcrop

See: blind apex.

buried placer

a. Old placer deposit that has been buried beneath a lava flow or other strata.

b. See: deep lead.


An orthorhombic mineral, Na (sub 6) (CO (sub 3) )(SO (sub 4) ) (sub 2) ; in small flat crystals, twins, and nodules; at Searles Lake, CA. Syn: teepleite.


An oolith or nodule in fireclay. It may have a high content of alumina or iron oxide.


A miner's term for any heavy two-person drill. The Burleigh was the first successful machine rock drill.

burley clay

A clay containing burls; specif. a diaspore-bearing clay in Missouri, usually averaging 45% to 65% alumina. See also: diaspore clay.


a. To permit a bit to become overheated in use.

b. To calcine. c. To pulverize with very heavy explosive charges.

burn cut

Type of parallel hole or holes cut for tunnel blasting; centrally located and not containing explosives. Outer loaded holes are designed to break the cut.


Said of slate or other impurity that adheres tightly to coal. Similarly, coal is said to be "burned to the roof" when it is hard to separate the roof rock from the coal.

burned bit

As a result of high-speed, excessive pressure, and poor water circulation, sufficient heat may be generated at the bottom of a borehole to cause a diamond crown to soften, resulting in displacement of diamonds and a ruined bit.

burned cut

A cut made in the face of a heading for which three or four holes are drilled normal to the face and in a triangle or square, 12 to 18 in (30.48 to 45.72 cm) on a side, with another hole in the center. One, two, or three holes are loaded and shot; the others relieve the pressure and induce breaking. A cavity is formed to which other shots in the face readily break. Used for esp. tough ground. Also called Michigan cut; woodchuck cut.

burned lime

Calcium oxide (quicklime) formed from limestone, or other forms of calcium carbonate, which has been calcined at high temperature to drive off the carbon dioxide. See also: burnt lime.

burn in

a. To run a bit with too little coolant until the heat generated by the bit fuses the cuttings, core, bit, and the bottom of the borehole.

b. To deliberately run a bit with reduced amount of coolant until the core is jammed inside the bit.

burning house

A furnace in which sulfide ores are calcined to form gaseous SO (sub 2) and leave the metal oxide, or in the case of noble metals, the metal itself.

burning oil

A common name for kerosine.

burning out

A loose term, usually used to describe the wearing away of furnace linings without a known reason.

burno man

A laborer who gets ore ready for a mechanical shovel or a hand shoveler.


A situation encountered in coal seams, usually near the outcrop, where the coal has undergone combustion and burned. Initiation sources could include lightning, forest fires, etc.

burn out

To salvage diamonds from a used bit by dissolving the matrix alloy with an acid or by use of an electrolytic process.

Burnside boring machine

This machine has been specially developed for boring in all types of ground, and incorporates a very important feature, that of controlling the water immediately if it is tapped. In boring, the hole is first prepared for the reception of a special rubber ring, two iron plates, and two wedges. When these are properly adjusted, the rubber washer is compressed and powerfully gripped on the sides of the borehole to effect a sound and reliable joint. If during boring operations water should rush out and the bore rods cannot be withdrawn, the two handwheels are screwed in; this presses india-rubber plugs onto the bore rods and effects a watertight joint.

burnt alum

Alum that has been dried at 200 degrees C, and powdered; AINH (sub 4) (SO (sub 4) ) (sub 2) or AIK(SO (sub 4) ) (sub 2) . A caustic. Syn: dried alum; exsiccated alum.

burnt iron

a. Iron which by long exposure to heat has suffered a change of structure and become brittle. It can be restored by careful forging at welding heat.

b. In the Bessemer and open-hearth processes, iron that has been exposed to oxidation until all of its carbon is gone, and an oxide of iron has been formed in the mass.

burnt lime

Calcitic lime, CaO, or dolomitic lime, CaO.MgO. See also: burned lime.

burnt metal

Metal that has become oxidized by overheating, and so is rendered useless for engineering purposes.

burnt stone

a. An antique carnelian, such as is sometimes found in ancient ruins and has apparently been acted on by fire.

b. A gemstone with color changed by heating; e.g., amethyst, which changes from purple to clear; or tiger-eye, which changes from yellowish-brown to reddish brown. Syn: heat-treated stone. CF: stained stone. See also: heated stone.


a. A term used in England for a rough or hard stone, such as a compact siliceous sandstone esp. hard to drill. Also spelled bur.

b. A knob, boss, nodule, or other hard mass of siliceous rock in a softer rock; a hard lump of ore in a softer vein. c. See: buhrstone.

burr rock

An aggregate of muscovite books and quartz.


See: buhrstone.


An explosive breaking of coal or rock in a mine due to pressure. In coal mines bursts may or may not be accompanied by a copious discharge of methane, carbon dioxide, or coal dust. Also called outburst; bounce; bump. See also: rock burst.


a. A hydraulic mechanism that, when inserted into a large-diameter shothole, breaks down the strata by means of pistons operating transversely.

b. Scot. A shot in a coal seam that has not been sheared or undercut. Equivalent to "shot off the solid." Also called bursting shot.


The phenomenon sometimes exhibited by refractories containing chrome ore, when exposed to iron oxide at high temperature, of having the exposed face swell and grow until it breaks away from the brick mass.

bursting charge

A small charge of fine powder placed in contact with a charge of coarse powder to ensure the ignition of the latter.

bursting time

The time between the application of an electric current and the setting off of an explosive charge. In seismic prospecting, it may be necessary to take into account the maximum difference in time lag between the bursting of the earliest and latest detonators in a series. In a series firing current of over 1 A direct current, the maximum difference with submarine seismic detonators is always less than 1 ms.

Burt filter

A stationary, intermittent filter in which the leaves are suspended vertically in a cylindrical vessel set on a considerable incline. The leaves are therefore ellipses. The slime cake is discharged by introducing air and water into the interior of the leaf. There is also a Burt filter of the continuous-rotating-drum type.


Any of several arrangements of hoisting tackle; usually one with a single and a double block.

Bushveld Complex

A great intrusive igneous body in the Transvaal, South Africa, that has undergone remarkable magmatic differentiation. It is by far the largest layered intrusion known. The Bushveld is the leading source of chromite.

Buss table

Shaking table for treatment of ore sands, comprising a deck supported by a Ferraris truss moved by eccentric.


A triclinic mineral, (Mn,Ca)Si (sub 3) O (sub 9) .

buster shot

See: breaking-in shot.

bus wire

Expendable heavy-gage bare copper wire used to connect detonators or series of detonators in parallel in underground blasting.


Scot. Outward; toward the shaft; outbye.


a. A flammable gaseous hydrocarbon, commonly bottled for use as fuel.

b. A gaseous flammable paraffin hydrocarbon, C (sub 4) H (sub 10) , occurring in either of two isometric forms: n-butane, CH (sub 3) CH (sub 2) CH (sub 2) CH (sub 3) ; or isobutane, CH (sub 3) CH(CH (sub 3) ) (sub 2) . The butanes occur in petroleum and natural gas.

butane flame methanometer

An instrument giving a continuous record of the methane concentration in mine air. It uses a small flame burning butane in a gauze-protected enclosure. Instead of observing the cap, thermocouples are used to show the increased temperature above the flame, and the resulting signal is displayed on a recording milliammeter. The instrument runs for at least a week and is accurate to about 0.05% methane. See also: methane tester type S.3.

Butchart table

A shaking table, toggle-actuated, with its deck supported in slipper bearings, and carrying curved riffles.


Arg. A monoclinic mineral occurring as oriented intergrowths with parabutlerite. A hydrous sulfate of iron.


A trigonal mineral, K (sub 2) Ca(CO (sub 3) ) (sub 2) ; dimorphous with fairchildite. Also spelled buetschliite.


a. Opposite of face, coal exposed at right angles to the face, and in contrast to the face, generally having a rough surface. Also called end in Scotland.

b. The butt of a slate quarry is where the overlying rock comes in contact with an inclined stratum of slate rock.

butt cleat

The minor cleat system, or jointing, in a coal seam, usually at right angles to the face cleat. Syn: end cleat. See also: cleat; butt joint.


a. A conspicuous hill or small mountain with relatively steep slopes or precipitous cliffs, often capped with a resistant layer of rock, and representing an erosion remnant carved from flat-lying rocks. The summit is smaller in extent than that of a mesa; many buttes in the arid and semiarid regions of the Western United States result from the wastage of mesas. Syn: mesa-butte.

b. An isolated hill having steep sides and a craggy, rounded, pointed, or otherwise irregular summit; e.g., a volcanic cone (such as Mount Shasta, CA, formerly known as Shasta Butte) or a volcanic butte. Etymol: French, knoll, hillock, inconspicuous rounded hill; rising ground. Pron: bewt.

butt entry

a. An entry driven at right angles to the butt.

b. The gallery driven at right angles with the butt cleat. An end-on entry. c. A gallery driven parallel with the main cleat of the coal seam. See also: entry.


A clear-yellow, rounded segregation of very pure carnotite found in the soft sandstone of Temple Rock, San Rafael Swell, UT.

Butters and Mein distributor

A turbo distributor that spreads sand evenly around a circular leaching tank in gold cyanidation.


A hexagonal mineral, Cu (sub 19) Cl (sub 4) (NO (sub 3) ) (sub 2) (OH) (sub 32) .2H (sub 2) O .

butt heading

See: butt entry.

butt joint

a. A joint between two abutting members lying approx. in the same plane. A welded butt joint may contain a variety of grooves.

b. See: butt cleat.


a. A corner formed by two coal faces more or less at right angles, such as the end of a working face; the fast side; any short piece of coal approx. at right angles to the face; a rib; the rib side. See also: rib.

b. Eng. That portion of a working face of coal, next to be taken down. c. The rib of coal exposed at one or both ends of a longwall face, to enable a cutter loader to commence its run; the coal removed by a cutter loader. See also: stable; web. d. Coal that has been undercut and is ready to be broken.


a. A globule of metal remaining in an assaying crucible or cupel after fusion has been completed.

b. That part of a weld that tears out in the destructive testing of spot-seam or projection-welded specimens. c. Globule of lead formed during fire assay of gold or silver ore.

button balance

A small, very delicate balance used for weighing assay buttons.

button fusion test

See: button test.

button rope conveyor

See: rope and button conveyor.

button test

A test designed to determine relative fusibility of frit or powder. So called because the completed specimens resemble buttons.

butt shot

In coal mining, a charge placed so that the face or burden is nearly parallel with the borehole.

butt side

The side of the working face of a coalbed in which the joints or cleats are least pronounced, as distinguished from the face side in which the joints are most pronounced.

butt weld

A weld made between two abutting unscarfed ends or edges without overlapping. Both the pin- and box-thread portions of petroleum drill pipe generally are butt-welded electrically to upset end tubing to form a complete section of drill pipe or rod.

butt-welded tube

A tube made by drawing mild steel strip through a bell, so that the strip is coiled into a tube, the edges being then pressed together and welded.

butyl rubber

Synthetic material, copolymer of butadiene and isobutane.

Buxton test

One of a set of tests carried out in a gallery at the Safety in Mines Research Station at Buxton, England. The tests are made to determine the likelihood or limits at which an explosive will ignite gas or coal dust, before it can be placed on the official permitted list. See also: permitted explosive.


Letter name specifying the dimensions of bits, core barrels, and drill rods in the B-size and W-group wireline diamond drilling system having a core diameter of 42 mm and a hole diameter of 60 mm. Syn: BX.


Letter name specifying the dimensions of core, core barrels, and casing in the B-size and X-series wireline diamond drilling system having a core diameter of 42 mm and a hole diameter of 60 mm. The BX designation for coring bits has been replaced by the BW designation. Syn: BW.

bye water

See: bank water.


a. A short passage used to get by or around a place it is not advisable to cross; e.g., a mine shaft. Also spelled byepass.

b. To pass to the side of an obstruction in a borehole by deflecting the hole. Syn: drill by. See also: wedge off. c. An alternative path, in a duct or pipe, for a fluid to flow from one point to another, with the direction determined by the opening or closing of valves or dampers in the main line as well as in the bypass. d. An arrangement of screens and chutes, or of piping, allowing material to be passed around a given part of a flow line. Much used to avoid feeding fine ore through a relatively coarse crusher, thus reducing load, wear, and chance of blockage. e. A small passage to permit equalization of the pressure on the two sides of a large valve so that it may be readily opened or closed.


Scot. A pit nearer the outcrop than the engine pit; an air pit.


A secondary or additional product; e.g., gallium is commercially recovered from the processing of bauxite to alumina. See also: coproduct.

byproduct oven

A coke oven consisting of a series of long, narrow chambers arranged in rows, and heated by flues in which are burned a portion of the combustible gases generated by the coking of the coal. All of the volatile products are saved and collected as ammonia, tar, gas, etc.

byproducts of coal

The products obtained from coal by destructive distillation and other processes.


An olive-green asbestiform variety of tremolite-actinolite. The term is used in the gem trade for a variety of quartz-containing, greenish, fibrous inclusions of actinolite or asbestos.


a. A tetragonal mineral, MgSb (sub 2) O (sub 6) .

b. A former name for a monoclinic polymorph of pyrrhotite. Also spelled bystromite.


A triclinic mineral, (Ca,Na)[Al,Si)AlSi (sub 2) O (sub 8) ] having 90 to 70 mol % Ca and 10 to 30 mol % Na; of the plagioclase series of the feldspar group; prismatic cleavage; white to gray; forms phenocrysts in some basalts and layered mafic-ultramafic intrusions


A channel or spillway designed to carry surplus water from a dam, reservoir, or aqueduct in order to prevent overflow.