Mining terminology

A
Abutment - In coalmining, (1) the weight of the rocks above a narrow roadway is
transferred to the solid coal along the sides, which act as abutments of the arch of
strata spanning the roadway; and (2) the weight of the rocks over a longwall face is
transferred to the front abutment, that is, the solid coal ahead of the face and the
back abutment, that is, the settled packs behind the face.
Acid deposition or acid rain – Refers loosely to a mixture of wet and dry
"deposition" (deposited material) from the atmosphere containing higher than
"normal" amount of nitric and sulfuric acids. The precursors orchemical
forerunners of acid rain formation result from both natural sources, such as
volcanoes and decaying vegetation, and man-made sources, primarily emissions of
sulfur and nitrogen oxides resulting from fossil fuel combustion.
Acid mine water- Mine water that contains free sulfuric acid, mainly due to the
weathering of iron pyrites.
Active workings - Any place in a mine where miners are normally required to
work or travel and which are ventilated and inspected regularly.
Adit - A nearly horizontal passagefrom the surface by which a mine is entered and
dewatered. A blind horizontal opening into a mountain, with only one entrance.
Advance - Mining in the same direction, or order of sequence; first mining as
distinguished from retreat.
Air split - The division of a current of air into two or more parts.
Airway - Any passagethrough which air is carried. Also known as an air course.
Anemometer - Instrument for measuring air velocity.
Angle of dip - The angle at which strata or mineral deposits are inclined to the
horizontal plane.
Angle of draw - In coal mine subsidence, this angle is assumed to bisect the angle
between the vertical and the angle of repose of the material and is 20° for flat
seams. For dipping seams, the angle of break increases, being 35.8° from the
vertical for a 40° dip. The main break occurs over the seam at an angle from the
vertical equal to half the dip.

Angle of repose - The maximum angle from horizontal at which a given material
will rest on a given surface without sliding or rolling.
Anticline - An upward fold or arch of rock strata.
Aquifer - A water-bearing bed of porous rock, often sandstone.
Arching - Fracture processesaround a mine opening, leading to stabilization by an
arching effect.
Area (of an airway) - Average width multiplied by average height of airway,
expressed in square feet.
Auger - A rotary drill that uses a screw device to penetrate, break, and then
transport the drilled material (coal).
Auxiliary operations - All activities supportive of but not contributing directly to
mining.
Auxiliary ventilation - Portion of main ventilating current directed to face of dead
end entry by means of an auxiliary fan and tubing.
Azimuth - A surveying term that references the angle measured clockwise from
any meridian (the established line of reference). The bearing is used to designate
direction. The bearing of a line is the acute horizontal angle between the meridian
and the line.
B
Back - The roof or upper part in any underground mining cavity.
Backfill– Mine waste or rock used to supportthe roofafter coal removal.
Barren - Said of rock or vein material containing no minerals of value, and of
strata without coal, or containing coal in seams too thin to be workable.
Barricading - Enclosing part of a mine to prevent inflow of noxious gasses from a
mine fire or an explosion.
Barrier - Something that bars or keeps out. Barrier pillars are solid blocks of coal
left between two mines or sections of a mine to prevent accidents due to inrushes
of water, gas, or from explosions or a mine fire.

Beam- A bar or straight girder used to supporta span of roof between two support
props orwalls.
Beambuilding - The creation of a strong, inflexible beam by bolting or otherwise
fastening together several weaker layers. In coal mining this is the intended basis
for roof bolting.
Bearing – A surveying term used to designate direction. The bearing of a line is
the acute horizontal angle between the meridian and the line. The meridian is an
established line of reference. Azimuths are angles measured clockwise from any
meridian.
Bearing plate - A plate used to distribute a given load. In roof bolting, the plate
used between the bolt head and the roof.
Bed - A stratum of coal or other sedimentary deposit.
Belt conveyor- A looped belt on which coal or other materials can be carried and
which is generally constructed of flame-resistant material or of reinforced rubber
or rubber-like substance.
Belt idler - A roller, usually of cylindrical shape, which is supported on a frame
and which, in turn, supports orguides a conveyor belt. Idlers are not powered but
turn by contact with the moving belt.
Belt take-up - A belt pulley, generally under a conveyor belt and inby the drive
pulley, kept under strong tension parallel to the belt line. Its purposeis to
automatically compensate for any slack in the belting created by start-up, etc.
Bench- One of to or more divisions of a coal seam separated by slate or formed by
the process ofcutting the coal.
Beneficiation- The treatment of mined material, making it more concentrated or
richer.
Berm - A pile or mound of material capable of restraining a vehicle.
Binder - A streak of impurity in a coal seam.

Bit - The hardened and strengthened device at the end of a drill rod that transmits
the energy of breakage to the rock. The size of the bit determines the size of the
hole. A bit may be either detachable from or integral with its supporting drill rod.
Bituminous coal – A middle rank coal (between subbituminous and anthracite)
formed by additional pressure and heat on lignite. Usually has a high Btu value and
may be referred to as "soft coal."
Black damp - A term generally applied to carbondioxide. Strictly speaking, it is a
mixture of carbondioxide and nitrogen. It is also applied to an atmosphere
depleted of oxygen, rather than having an excess of carbondioxide.
Blasting agent - Any material consisting of a mixture of a fuel and an oxidizer.
Blasting cap - A detonator containing a charge of detonating compound, which is
ignited by electric current or the spark of a fuse. Used for detonating explosives.
Blasting circuit - Electric circuits used to fire electric detonators or to ignite an
igniter cord by means of an electric starter.
Bleederor bleeder entries - Special air courses developed and maintained as part
of the mine ventilation system and designed to continuously move air-methane
mixtures emitted by the gob or at the active face away from the active workings
and into mine-return air courses. Alt: Exhaust ventilation lateral.
Bolt torque - The turning force in foot-pounds applied to a roofbolt to achieve an
installed tension.
Borehole - Any deep or long drill-hole, usually associated with a diamond drill.
Bottom - Floor or underlying surface of an underground excavation.
Boss - Any member of the managerial ranks who is directly in charge of miners
(e.g., "shift-boss," "face-boss,""fire-boss," etc.).
Box-type magazine - A small, portable magazine used to store limited quantities
of explosives or detonators for short periods of time at locations in the mine which
are convenient to the blasting sites at which they will be used.

Brattice or brattice cloth - Fire-resistant fabric or plastic partition used in a mine
passage to confine the air and force it into the working place. Also termed "line
brattice," "line canvas," or "line curtain."
Break line - The line that roughly follows the rear edges of coal pillars that are
being mined. The line along which the roofof a coal mine is expected to break.
Breakthrough- A passage for ventilation that is cut through the pillars between
rooms.
Bridge carrier- A rubber-tire-mounted mobile conveyor, about 10 meters long,
used as an intermediate unit to create a system of articulated conveyors between a
mining machine and a room or entry conveyor.
Bridge conveyor- A short conveyor hung from the boomof mining or lading
machine or haulage system with the other end attached to a receiving bin that
dollies along a frame supported bythe room or entry conveyor, tailpiece. Thus, as
the machine boom moves, the bridge conveyor keeps it in constant connection with
the tailpiece.
Brow - A low place in the roofof a mine, giving insufficient headroom.
Brushing - Digging up the bottom or taking down the top to give more headroom
in roadways.
Btu – British thermal unit. A measure of the energy required to raise the
temperature of one pound of water one degree Fahrenheit.
Bug dust - The fine particles of coal or other material resulting form the boring or
cutting of the coal face by drill or machine.
Bump (or burst) - A violent dislocation of the mine workings which is attributed
to severe stresses in the rock surrounding the workings.
Butt cleat- A short, poorly defined vertical cleavage plane in a coalseam, usually
at right angles to the long face cleat.
Butt entry - A coal mining term that has different meanings in different locations.
It can be synonymous with panel entry, submain entry, or in its older sense it refers
to an entry that is "butt" onto the coalcleavage (that is, at right angles to the face).

C
Cage - In a mine shaft, the device, similar to an elevator car, that is used for
hoisting personnel and materials.
Calorific value - The quantity of heat that can be liberated from one pound of coal
or oil measured in BTU's.
Cannel coal - A massive, non-caking block coal with a fine, even grain and a
conchoidal fracture which has a high percentage of hydrogen, burns with a long,
yellow flame, and is extremely easy to ignite.
Canopy - A protective covering of a cab on a mining machine.
Cap - A miner's safety helmet. Also, a highly sensitive, encapsulated explosive
that is used to detonate larger but less sensitive explosives.
Cap block - A flat piece of wood inserted between the top of the prop and the roof
to provide bearing support.
Car - A railway wagon, especially any of the wagons adapted to carrying coal, ore,
and waste underground.
Car-dump - The mechanism for unloading a loaded car.
Carbide bit - More correctly, cemented tungsten carbide. A cutting or drilling bit
for rock or coal, made by fusing an insert of molded tungsten carbide to the cutting
edge of a steel bit shank.
Cast- A directed throw; in strip-mining, the overburden is cast from the coalto the
previously mined area.
Certified - Describes a person who has passed an examination to do a required job.
Chain conveyor - A conveyor on which the material is moved along solid pans
(troughs) by the action of scraper crossbars attached to powered chains.
Chain pillar - The pillar of coalleft to protect the gangway or entry and the
parallel airways.
Check curtain - Sheet of brattice cloth hung across an airway to controlthe
passage of the air current.

Chock - Large hydraulic jacks used to supportroofin longwall and shortwall
mining systems.
Clay vein - A bodyof clay-like material that fills a void in a coal bed.
Cleat- The vertical cleavage of coalseams. The main set of joints along which
coal breaks when mined.
CleanAir Act Amendments of 1990 – A comprehensive set of amendments to
the federal law governing the nation's air quality. The Clean Air Act was originally
passed in 1970 to address significant air pollution problems in our cities. The 1990
amendments broadened and strengthened the original law to address specific
problems such as acid deposition, urban smog, hazardous air pollutants and
stratospheric ozone depletion.
CleanCoalTechnologies– A number of innovative, new technologies designed
to use coal in a more efficient and cost-effective manner while enhancing
environmental protection. Several promising technologies include: fluidized-bed
combustion, integrated gasification combined cycle, limestone injection multi-
stage burner, enhanced flue gas desulfurization (or "scrubbing"), coal liquefaction
and coalgasification.
Coal- A solid, brittle, more or less distinctly stratified combustible carbonaceous
rock, formed by partial to complete decomposition of vegetation; varies in color
from dark brown to black; not fusible without decomposition and very insoluble.
Coaldust - Particles of coal that can pass a No. 20 sieve.
CoalGasification– The conversion of coal into a gaseous fuel.
Coalmine - An area of land and all structures, facilities, machinery, tools,
equipment, shafts, slopes, tunnels, excavations, and other property, real or
personal, placed upon, under, or above the surface of such land by any person,
used in extracting coal from its natural deposits in the earth by any means or
method, and the work of preparing the coal so extracted, including coal preparation
facilities. British term is "colliery".
Coalreserves - Measured tonnages of coal that have been calculated to occurin a
coal seam within a particular property.

Coalwashing – The process ofseparating undesirable materials from coal based
on differences in densities. Pyritic sulfur, or sulfur combined with iron, is heavier
and sinks in water; coal is lighter and floats.
Coke – A hard, dry carbon substanceproduced by heating coal to a very high
temperature in the absenceof air.
Collar- The term applied to the timbering or concrete around the mouth or top of
a shaft. The beginning point of a shaft or drill hole at the surface.
Colliery - British name for coal mine.
Column flotation – A precombustion coal cleaning technology in which coal
particles attach to air bubbles rising in a vertical column. The coalis then removed
at the top of the column.
Comminution - The breaking, crushing, or grinding of coal, ore, or rock.
Competent rock - Rockwhich, because of its physical and geological
characteristics, is capable of sustaining openings without any structural support
except pillars and walls left during mining (stalls, light props, and roof bolts are
not considered structural support).
Contact- The place or surface where two different kinds of rocks meet. Applies to
sedimentary rocks, as the contact between a limestone and a sandstone, for
example, and to metamorphic rocks;and it is especially applicable between
igneous intrusions and their walls.
Continuous miner - A machine that constantly extracts coal while it loads itself.
This is to be distinguished from a conventional, or cyclic, unit which must stop the
extraction process in order for loading to commence.
Contour - An imaginary line that connects all points on a surface having the same
elevation.
Conventional mining – The first fully-mechanized underground mining method
involving the insertion of explosives in a coalseam, the blasting of the seam, and
the removal of the coal onto a conveyor or shuttle car by a loading machine.

Conveyor- An apparatus for moving material from one point to another in a
continuous fashion. This is accomplished with an endless (that is, looped)
processionof hooks, buckets, wide rubber belt, etc.
Core sample – A cylinder sample generally 1-5" in diameter drilled out of an area
to determine the geologic and chemical analysis of the overburden and coal.
Cover- The overburden of any deposit.
Creep- The forcing of pillars into soft bottomby the weight of a strong roof. In
surface mining, a very slow movement of slopes downhill.
Crib - A roof supportof prop timbers or ties, laid in alternate cross-layers, log-
cabin style. It may or may not be filled with debris. Also may be called a chockor
cog.
Cribbing - The construction of cribs or timbers laid at right angles to each other,
sometimes filled with earth, as a roof supportor as a supportfor machinery.
Crop coal - Coal at the outcrop of the seam. It is usually considered of inferior
quality due to partial oxidation, although this is not always the case.
Crossbar- The horizontal member of a roof timber set supported by props located
either on roadways or at the face.
Crosscut- A passageway driven between the entry and its parallel air courseor air
courses for ventilation purposes. Also, a tunnel driven from one seam to another
through or across the intervening measures; sometimes called "crosscuttunnel", or
"breakthrough". In vein mining, an entry perpendicular to the vein.
Cross entry - An entry running at an angle with the main entry.
Crusher - A machine for crushing rock or other materials. Among the various
types of crushers are the ball mill, gyratory crusher, Handsel mill, hammer mill,
jaw crusher, rod mill, rolls, stamp mill, and tube mill.
Cutter; Cutting machine - A machine, usually used in coal, that will cut a 10- to
15-cm slot. The slot allows room for expansion of the broken coal. Also applies to
the man who operates the machine and to workers engaged in the cutting of coal by
prick or drill.

Cycle mining - A system of mining in more than one working place at a time, that
is, a miner takes a lift from the face and moves to another face while permanent
roof supportis established in the previous working face.
D
Demonstratedreserves – A collective term for the sum of coal in both measured
and indicated resources and reserves.
Deposit- Mineral depositor ore depositis used to designate a natural occurrence
of a useful mineral, or an ore, in sufficient extent and degree of concentration to
invite exploitation.
Depth - The word alone generally denotes vertical depth below the surface. In the
case of incline shafts and boreholes it may mean the distance reached from the
beginning of the shaft or hole, the borehole depth, or the inclined depth.
Detectors -Specialized chemical or electronic instruments used to detect mine
gases.
Detonator- A device containing a small detonating charge that is used for
detonating an explosive, including, but not limited to, blasting caps, exploders,
electric detonators, and delay electric blasting caps.
Developmentmining - Work undertaken to open up coal reserves as distinguished
from the work of actual coal extraction.
Diffusion - Blending of a gas and air, resulting in a homogeneous mixture.
Blending of two or more gases.
Diffuser fan - A fan mounted on a continuous miner to assist and direct air
delivery from the machine to the face.
Dilute - To lower the concentration of a mixture; in this casethe concentration of
any hazardous gas in mine air by addition of fresh intake air.
Dilution - The contamination of ore with barren wall rock in stopping.
Dip - The inclination of a geologic structure (bed, vein, fault, etc.) from the
horizontal; dip is always measured downwards at right angles to the strike.

Dragline – A large excavation machine used in surface mining to remove
overburden (layers of rock and soil) covering a coal seam. The dragline casts a
wire rope-hung bucket a considerable distance, collects the dug material by pulling
the bucket toward itself on the ground with a second wire rope (or chain), elevates
the bucket, and dumps the material on a spoil bank, in a hopper, or on a pile.
Drainage - The process ofremoving surplus ground or surface water either by
artificial means or by gravity flow.
Draw slate - A soft slate, shale, or rock from approximately 1 cm to 10 cm thick
and located immediately above certain coal seams, which falls quite easily when
the coal supportis withdrawn.
Drift - A horizontal passageunderground. A drift follows the vein, as
distinguished from a crosscutthat intersects it, or a level or gallery, which may do
either.
Drift mine – An underground coal mine in which the entry or access is above
water level and generally on the slope of a hill, driven horizontally into a coal
seam.
Drill - A machine utilizing rotation, percussion (hammering), or a combination of
both to make holes. If the hole is much over 0.4m in diameter, the machine is
called a borer.
Drilling - The use of such a machine to create holes for exploration or for loading
with explosives.
Dummy - A bag filled with sand, clay, etc., used for stemming a charged hole.
Dump - To unload; specifically, a load of coal or waste; the mechanism for
unloading, e.g. a car dump (sometimes called tipple); or, the pile created by such
unloading, e.g. a waste dump (also called heap, pile, tip, spoil pike, etc.).
E
Electricalgrounding - To connect with the ground to make the earth part of the
circuit.
Entry - An underground horizontal or near-horizontal passage used for haulage,
ventilation, or as a mainway; a coal heading; a working place where the coal is

extracted from the seam in the initial mining; same as "gate" and "roadway," both
British terms.
Evaluation - The work involved in gaining a knowledge of the size, shape,
position and value of coal.
Exploration - The search for mineral deposits and the work done to prove or
establish the extent of a mineral deposit. Alt: Prospecting and subsequent
evaluation.
Explosive - Any rapidly combustive or expanding substance. The energy released
during this rapid combustion or expansion can be used to break rock.
Extraction - The process ofmining and removal of cal or ore from a mine.
F
Face – The exposed area of a coalbed from which coal is being extracted.
Face cleat - The principal cleavage plane or joint at right angles to the
stratification of the coal seam.
Face conveyor- Any conveyor used parallel to a working face which delivers coal
into another conveyor or into a car.
Factorof safety- The ratio of the ultimate breaking strength of the material to the
force exerted against it. If a rope will break under a load of 6000 lbs., and it is
carrying a load of 2000 lbs., its factor of safety is 6000 divided by 2000 which
equals 3.
Fall - A mass of roof rock or coal which has fallen in any part of a mine.
Fan, auxiliary - A small, portable fan used to supplement the ventilation of an
individual working place.
Fan, booster- A large fan installed in the main air current, and thus in tandem
with the main fan.
Fan signal - Automation device designed to give alarm if the main fan slows down
or stops.

Fault - A slip-surface between two portions of the earth's surface that have moved
relative to each other. A fault is a failure surface and is evidence of severe earth
stresses.
Fault zone - A fault, instead of being a single clean fracture, may be a zone
hundreds or thousands of feet wide. The fault zone consists of numerous
interlacing small faults or a confused zone of gouge, breccia, or mylonite.
Feeder- A machine that feeds coal onto a conveyor belt evenly.
Fill - Any material that is put backin place of the extracted ore to provide ground
support.
Fire damp - The combustible gas, methane, CH4. Also, the explosive methane-air
mixtures with between 5% and 15% methane. A combustible gas formed in mines
by decomposition of coal or other carbonaceous matter, and that consists chiefly of
methane.
Fissure - An extensive crack, break, or fracture in the rocks.
Fixed carbon – The part of the carbon that remains behind when coalis heated in
a closed vessel until all of the volatile matter is driven off.
Flat-lying - Said of deposits and coal seams with a dip up to 5 degrees.
Flight - The metal strap or crossbarattached to the drag chain-and-flight conveyor.
Floatdust - Fine coal-dust particles carried in suspensionby air currents and
eventually deposited in return entries. Dust consisting of particles of coal that can
pass through a No. 200 sieve.
Floor- That part of any underground working upon which a personwalks or upon
which haulage equipment travels; simply the bottom or underlying surface of an
underground excavation.
Flue Gas Desulfurization – Any of several forms of chemical/physical processes
that remove sulfur compounds formed during coal combustion. The devices,
commonly called "scrubbers,"combine the sulfur in gaseous emissions with
another chemical medium to form inert "sludge" which must then be removed for
disposal.

Fluidized Bed Combustion – A process with a high degree of ability to remove
sulfur from coal during combustion. Crushed coal and limestone are suspended in
the bottom of a boiler by an upward stream of hot air. The coal is burned in this
bubbling, liquid-like (or "fluidized") mixture. Rather than released as emissions,
sulfur from combustion gases combines with the limestone to form a solid
compound recovered with the ash.
Fly ash– The finely divided particles of ash suspended in gases resulting from the
combustion of fuel. Electrostatic precipitators are used to remove fly ash from the
gases prior to the release from a power plant's smokestack.
Formation – Any assemblage of rocks which have some character in common,
whether of origin, age, or composition. Often, the word is loosely used to indicate
anything that has been formed or brought into its present shape.
Fossilfuel – Any naturally occurring fuel of an organic nature, such as coal, crude
oil and natural gas.
Fracture - A general term to include any kind of discontinuity in a bodyof rock if
produced by mechanical failure, whether by shear stress or tensile stress. Fractures
include faults, shears, joints, and planes of fracture cleavage.
Friable - Easy to break, or crumbling naturally. Descriptive of certain rocks and
minerals.
Fuse - A cord-like substanceused in the ignition of explosives. Black powder is
entrained in the cord and, when lit, burns along the cord at a set rate. A fuse can be
safely used to ignite a cap, which is the primer for an explosive.
G
Gallery - A horizontal or a nearly horizontal underground passage, either natural
or artificial.
Gasification– Any of various processesbywhich coal is turned into low, medium,
or high Btu gases.
Gathering conveyor; gathering belt - Any conveyor which is used to gather coal
from other conveyors and deliver it either into mine cars or onto another conveyor.
The term is frequently used with belt conveyors placed in entries where a number
of room conveyors deliver coal onto the belt.

Geologist- One who studies the constitution, structure, and history of the earth's
crust, conducting research into the formation and dissolution of rock layers,
analyzing fossil and mineral content of layers, and endeavoring to fix historical
sequence of development by relating characteristics to known geological
influences (historical geology).
Gob - The term applied to that part of the mine from which the coal has been
removed and the spacemore or less filled up with waste. Also, the loose waste in a
mine. Also called goaf.
Global climate change – This term usually refers to the gradual warming of the
earth caused by the greenhouse effect. Many scientists believe this is the result of
man-made emissions of greenhouse gases such as carbon dioxide,
chlorofluorocarbons (CFC) and methane, although there is no agreement among
the scientific community on this controversial issue.
Grain - In petrology, that factor of the texture of a rock composedofdistinct
particles or crystals which depends upon their absolute size.
Grizzly - Coursescreening or scalping device that prevents oversized bulk
material form entering a material transfer system; constructed of rails, bars, beams,
etc.
Ground control - The regulation and final arresting of the closure of the walls of a
mined area. The term generally refers to measures taken to prevent roof falls or
coal bursts.
Ground pressure - The pressure to which a rock formation is subjected by the
weight of the superimposed rockand rock material or by diastrophic forces created
by movements in the rocks forming the earth's crust. Such pressures may be great
enough to cause rocks having a low compressional strength to deform and be
squeezed into and close a borehole or other underground opening not adequately
strengthened by an artificial support, suchas casing or timber.
Gunite - A cement applied by spraying to the roof and sides of a mine passage.
H
Haulage - The horizontal transport of ore, coal, supplies, and waste. The vertical
transport of the same is called hoisting.

Haulageway- Any underground entry or passageway that is designed for transport
of mined material, personnel, or equipment, usually by the installation of track or
belt conveyor.
Headframe - The structure surmounting the shaft which supports the hoist rope
pulley, and often the hoist itself.
Heading - A vein above a drift. An interior level or airway driven in a mine. In
longwall workings, a narrow passage driven upward from a gangway in starting a
working in order to give a loose end.
Head section- A term used in both belt and chain conveyor work to designate that
portion of the conveyor used for discharging material.
Heaving - Applied to the rising of the bottom after removal of the coal; a sharp
rise in the floor is called a "hogsback".
Highwall – The unexcavated face of exposed overburden and coal in a surface
mine or in a face or bank on the uphill side of a contour mine excavation.
Highwall miner – A highwall mining system consists of a remotely controlled
continuous miner which extracts coal and conveys it via augers, belt or chain
conveyors to the outside. The cut is typically a rectangular, horizontal cut from a
highwall bench, reaching depths of several hundred feet or deeper.
Hogsback -A sharp rise in the floor of a seam.
Hoist - A drum on which hoisting rope is wound in the engine house, as the cage
or skip is raised in the hoisting shaft.
Hoisting - The vertical transport coal or material.
Horizon - In geology, any given definite position or interval in the stratigraphic
column or the scheme of stratigraphic classification; generally used in a relative
sense.
Horseback - A mass of material with a slippery surface in the roof; shaped like a
horse's back.
Hydraulic - Of or pertaining to fluids in motion. Hydraulic cement has a
composition which permits it to set quickly under water. Hydraulic jacks lift

through the force transmitted to the movable part of the jack by a liquid. Hydraulic
control refers to the mechanical control of various parts of machines, such as coal
cutters, loaders, etc., through the operation or action of hydraulic cylinders.
Hydrocarbon – A family of chemical compounds containing carbonand hydrogen
atoms in various combinations, found especially in fossil fuels.
I
Inby - In the direction of the working face.
Incline - Any entry to a mine that is not vertical (shaft) or horizontal (adit). Often
incline is reserved for those entries that are too steep for a belt conveyor (+17
degrees -18 degrees), in which case a hoist and guide rails are employed. A belt
conveyor incline is termed a slope. Alt: Secondaryinclined opening, driven
upward to connect levels, sometimes on the dip of a deposit;also called "inclined
shaft".
Incompetent - Applied to strata, a formation, a rock, or a rockstructure not
combining sufficient firmness and flexibility to transmit a thrust and to lift a load
by bending.
Indicated coalresources – Coal for which estimates of the rank, quality, and
quantity have been computed partly from sample analyses and measurements and
partly from reasonable geologic projections. The points of observation are ½ to 1
½ miles apart. Indicated coalis projected to extend as an ½ mile wide belt that lies
more than ¼ mile from the outcrop or points of observation or measurement.
Inferred coalresources – Coalin unexplored extensions of the demonstrated
resources for which estimates of the quality and size are based on geologic
evidence and projection. Quantitative estimates are based largely on broad
knowledge of the geologic character of the deposit and for which there are few, if
any, samples or measurements. The estimates are based on an assumed continuity
or repletion of which there is geologic evidence; this evidence may include
comparison with deposits of similar type. Bodies that are completely concealed
may be included if there is specific geologic evidence of their presence. The points
of observation are 1 ½ to 6 miles apart.
In situ - In the natural or original position. Applied to a rock, soil, or fossil when
occurring in the situation in which it was originally formed or deposited.

Intake - The passage through which fresh air is drawn or forced into a mine or to a
section of a mine.
Intermediate section- A term used in belt and chain conveyor network to
designate a section of the conveyor frame occupying a position between the head
and footsections.
Immediate roof - The roof strata immediately above the coalbed, requiring
supportduring the excavation of coal.
Isopach- A line, on a map, drawn through points of equal thickness of a
designated unit. Synonym for isopachous line; isopachyte.
J
Jackleg- A percussiondrill used for drifting or stopping that is mounted on a
telescopic leg which has an extension of about 2.5 m. The leg and machine are
hinged so that the drill need not be in the same direction as the leg.
Jackrock – A caltrop or other object manufactured with one or more rounded or
sharpened points, which when placed or thrown present at least one point at such
an angle that it is peculiar to and designed for use in puncturing or damaging
vehicle tires. Jackrocks are commonly used during labor disputes.
Job SafetyAnalysis (J.S.A.) - A job breakdown that gives a safe, efficient job
procedure.
Joint - A divisional plane or surface that divides a rock and along which there has
been no visible movement parallel to the plane or surface.
K
Kettle bottom - A smooth, rounded piece of rock, cylindrical in shape, which may
drop out of the roof of a mine without warning. The origin of this feature is thought
to be the remains of the stump of a tree that has been replaced by sediments so that
the original form has been rather well preserved.
Kerf - The undercut of a coal face.
L

Lamp - The electric cap lamp worn for visibility. Also, the flame safety lamp used
in coal mines to detect methane gas concentrations and oxygen deficiency.
Layout - The design or pattern of the main roadways and workings. The proper
layout of mine workings is the responsibility of the manager aided by the planning
department.
Lift - The amount of coal obtained from a continuous miner in one mining cycle.
Liquefaction – The process ofconverting coalinto a synthetic fuel, similar in
nature to crude oil and/or refined products, suchas gasoline.
Lithology - The character of a rock described in terms of its structure, color,
mineral composition, grain size, and arrangement of its component parts; all those
visible features that in the aggregate impart individuality of the rock. Lithology is
the basis of correlation in coal mines and commonly is reliable over a distance of a
few miles.
Load - To place explosives in a drill hole. Also, to transfer broken material into a
haulage device.
Loading machine - Any device for transferring excavated coal into the haulage
equipment.
Loading pocket - Transfer point at a shaft where bulk material is loaded by bin,
hopper, and chute into a skip.
Longwall Mining – One of three major underground coalmining methods
currently in use. Employs a steal plow, or rotation drum, which is pulled
mechanically back and forth across a face of coal that is usually several hundred
feet long. The loosened coal falls onto a conveyor for removal from the mine.
Loose coal- Coal fragments larger in size than coal dust.
Low voltage - Up to and including 660 volts by federal standards.
M
Main entry - A main haulage road. Where the coalhas cleats, main entries are
driven at right angles to the face cleats.

Main fan - A mechanical ventilator installed at the surface; operates by either
exhausting or blowing to induce airflow through the mine roadways and workings.
Manhole - A safety hole constructed in the side of a gangway, tunnel, or slope in
which miner can be safe from passing locomotives and car. Also called a refuge
hole.
Man trip - A carrier of mine personnel, by rail or rubber tire, to and from the work
area.
Manway- An entry used exclusively for personnel to travel form the shaft bottom
or drift mouth to the working section; it is always on the intake air side in gassy
mines. Also, a small passageat one side or both sides of a breast, used as a
traveling way for the miner, and sometimes, as an airway, or chute, or both.
Measuredcoalresources – Coal for which estimates of the rank, quality, and
quantity have been computed from sample analyses and measurements from
closely spaced and geologically well-known sample sites, such as outcrops,
trenches, mine workings, and drill holes. The points of observation and
measurement are so closely spaced and the thickness and extent of coals are so
well defined that the tonnage is judged to be accurate within 20 percent of true
tonnage. Although the spacing of the points of observation necessary to
demonstrate continuity of the coal differs from region to region according to the
character of the coal beds, the points of observation are no greater than ½ mile
apart. Measured coal is projected to extend as a ¼-mile wide belt from the outcrop
or points of observation or measurement.
Meridian -– A surveying term that establishes a line of reference. The bearing is
used to designate direction. The bearing of a line is the acute horizontal angle
between the meridian and the line. Azimuths are angles measured clockwise from
any meridian.
Methane – A potentially explosive gas formed naturally from the decay of
vegetative matter, similar to that which formed coal. Methane, which is the
principal component of natural gas, is frequently encountered in underground coal
mining operations and is kept within safe limits through the use of extensive mine
ventilation systems.
Methane monitor - An electronic instrument often mounted on a piece of mining
equipment, that detects and measures the methane content of mine air.

Mine development - The term employed to designate the operations involved in
preparing a mine for ore extraction. These operations include tunneling, sinking,
cross-cutting, drifting, and raising.
Mine mouth electric plant – A coal burning electric-generating plant built near a
coal mine.
Miner - One who is engaged in the business or occupationof extracting ore, coal,
precious substances, orother natural materials from the earth's crust.
Mineral - An inorganic compound occurring naturally in the earth's crust, with a
distinctive set of physical properties, and a definite chemical composition.
Mining Engineer- A person qualified by education, training, and experience in
mining engineering. A trained engineer with knowledge of the science, economics,
and arts of mineral location, extraction, concentration and sale, and the
administrative and financial problems of practical importance in connection with
the profitable conductof mining.
Misfire - The complete or partial failure of a blasting charge to explode as
planned.
MSHA - Mine Safety and Health Administration; the federal agency which
regulates coal mine health and safety.
Mud cap - A charge of high explosive fired in contactwith the surface of a rock
after being covered with a quantity of wet mud, wet earth, or sand, without any
borehole being used. Also termed adobe, dobie, and sandblast (illegal in coal
mining).
N
Natural ventilation - Ventilation of a mine without the aid of fans or furnaces.
Nip - Device at the end of the trailing cable of a mining machine used for
connecting the trailing cable to the trolley wire and ground.
O
Open end pillaring - A method of mining pillars in which no stump is left; the
pockets driven are open on the gob side and the roof is supported bytimber.

Outby; outbye - Nearer to the shaft, and hence farther from the working face.
Toward the mine entrance. The oppositeof inby.
Outcrop – Coal that appears at or near the surface.
Overburden – Layers of soil and rock covering a coal seam. Overburden is
removed prior to surface mining and replaced after the coal is taken from the seam.
Overcast(undercast) - Enclosed airway which permits one air current to pass
over (under) another without interruption.
P
Panel- A coal mining block that generally comprises one operating unit.
Panic bar - A switch, in the shape of a bar, used to cut off power at the machine in
case of an emergency.
Parting - (1) A small joint in coalor rock; (2) a layer of rock in a coal seam; (3) a
side track or turnout in a haulage road.
Peat– The partially decayed plant matter found in swamps and bogs, one of the
earliest stages of coal formation.
Percentageextraction - The proportionof a coalseam which is removed from the
mine. The remainder may represent coalin pillars or coal which is too thin or
inferior to mine or lost in mining. Shallow coal mines working under townships,
reservoirs, etc., may extract 50%, or less, of the entire seam, the remainder being
left as pillars to protect the surface. Under favorable conditions, longwall mining
may extract from 80 to 95% of the entire seam. With pillar methods of working,
the extraction ranges from 50 to 90% depending on local conditions.
Percussiondrill - A drill, usually air powered, that delivers its energy through a
pounding or hammering action.
Permissible - That which is allowable or permitted. It is most widely applied to
mine equipment and explosives of all kinds which are similar in all respects to
samples that have passed certain tests of the MSHA and can be used with safety in
accordancewith specified conditions where hazards from explosive gas or coal
dust exist.

Permit – As it pertains to mining, a document issued by a regulatory agency that
gives approval for mining operations to take place.
Piggy-back - A bridge conveyor.
Pillar - An area of coalleft to supportthe overlying strata in a mine; sometimes
left permanently to supportsurface structures.
Pillar robbing - The systematic removal of the coal pillars between rooms or
chambers to regulate the subsidenceof the roof. Also termed "bridging back" the
pillar, "drawing" the pillar, or "pulling" the pillar.
Pinch - A compressionof the walls of a vein or the roof and floor of a coalseam
so as to "squeeze" out the coal.
Pinch – A compression of the roof and floor of a coal seam so as to "squeeze" out
the coal.
Pinning - Roofbolting.
Pitch - The inclination of a seam; the rise of a seam.
Plan - A map showing features suchas mine workings or geological structures on
a horizontal plane.
Pneumoconiosis -A chronic disease of the lung arising from breathing coal dust.
Portal - The structure surrounding the immediate entrance to a mine; the mouth of
an adit or tunnel.
Portalbus - Track-mounted, self-propelled personnel carrier that holds 8 to 12
people.
Post- The vertical member of a timber set.
Preparationplant - A place where coalis cleaned, sized, and prepared for market.
Primary roof - The main roofabove the immediate top. Its thickness may vary
from a few to several thousand feet.

Primer (booster) - A package or cartridge of explosive which is designed
specifically to transmit detonation to other explosives and which does not contain a
detonator.
Prop - Coal mining term for any single postused as roofsupport. Props may be
timber or steel; if steel--screwed, yieldable, or hydraulic.
Proximate analysis - A physical, or non-chemical, test of the constitution of coal.
Not precise, but very useful for determining the commercial value. Using the same
sample (1 gram) under controlled heating at fixed temperatures and time periods,
moisture, volatile matter, fixed carbon and ash content are successfully determined.
Sulfur and Btu content are also generally reported with a proximate analysis.
Pyrite - A hard, heavy, shiny, yellow mineral, FeS2 or iron disulfide, generally in
cubic crystals. Also called iron pyrites, fool's gold, sulfur balls. Iron pyrite is the
most common sulfide found in coal mines.
Q
R
Raise - A secondary or tertiary inclined opening, vertical or near-vertical opening
driven upward form a level to connect with the level above, or to explore the
ground for a limited distance above one level.
Ramp - A secondary or tertiary inclined opening, driven to connectlevels, usually
driven in a downward direction, and used for haulage.
Ranks of coal – The classification of coalby degree of hardness, moisture and
heat content. "Anthracite" is hard coal, almost pure carbon, used mainly for heating
homes. "Bituminous" is soft coal. It is the most common coal found in the United
States and is used to generate electricity and to make coke for the steel industry.
"Subbituminous" is a coal with a heating value between bituminous and lignite. It
has low fixed carbon and high percentages of volatile matter and moisture.
"Lignite" is the softest coal and has the highest moisture content. It is used for
generating electricity and for conversion into synthetic gas. In terms of Btu or
"heating" content, anthracite has the highest value, followed by bituminous,
subbituminous and lignite.
Reclamation– The restoration of land and environmental values to a surface mine
site after the coal is extracted. Reclamation operations are usually underway as

soonas the coalhas been removed from a mine site. The process includes restoring
the land to its approximate original appearance by restoring topsoiland planting
native grasses and ground covers.
Recovery- The proportionor percentage of coal or ore mined from the original
seam or deposit.
Red dog - A nonvolatile combustion productof the oxidation of coal or coal
refuse. Most commonly applied to material resulting from in situ, uncontrolled
burning of coal or coal refuse piles. It is similar to coalash.
Regulator- Device (wall, door)used to controlthe volume of air in an air split.
Reserve – That portion of the identified coal resource that can be economically
mined at the time of determination. The reserve is derived by applying a recovery
factor to that component of the identified coalresource designated as the reserve
base.
Resinbolting - A method of permanent roof supportin which steel rods are
grouted with resin.
Resources– Concentrations of coalin suchforms that economic extraction is
currently or may become feasible. Coal resources broken down by identified and
undiscovered resources. Identified coal resources are classified as demonstrated
and inferred. Demonstrated resources are further broken down as measured and
indicated. Undiscovered resources are broken down as hypothetical and
speculative.
Respirable dust - Dust particles 5 microns or less in size.
Respirable dust sample - A sample collected with an approved coal mine dust
sampler unit attached to a miner, or so positioned as to measure the concentration
of respirable dustto which the miner is exposed, and operated continuously over
an entire work shift of such miner.
Retreatmining - A system of robbing pillars in which the robbing line, or line
through the faces of the pillars being extracted, retreats from the boundary toward
the shaft or mine mouth.
Return - The air or ventilation that has passed through all the working faces of a
split.

Return idler - The idler or roller underneath the cover or cover plates on which
the conveyor belt rides after the load which it was carrying has been dumped at the
head section and starts the return trip toward the footsection.
Rib - The side of a pillar or the wall of an entry. The solid coal on the side of any
underground passage. Same as rib pillar.
Rider - A thin seam of coal overlying a thicker one.
Ripper - A coal extraction machine that works by tearing the coal from the face.
Rob - To extract pillars of coal previously left for support.
Robbed out area - Describes that part of a mine from which the pillars have been
removed.
Roll - (1) A high place in the bottom or a low place in the top of a mine passage,
(2) a local thickening of roof or floor strata, causing thinning of a coalseam.
Roll protection- A framework, safety canopy, or similar protection for the
operator when equipment overturns.
Roof- The stratum of rockor other material above a coal seam; the overhead
surface of a coal working place. Same as "back" or "top."
Roofbolt - A long steel bolt driven into the roof of underground excavations to
supportthe roof, preventing and limiting the extent of rooffalls. The unit consists
of the bolt (up to 4 feet long), steel plate, expansion shell, and pal nut. The use of
roof bolts eliminates the need for timbering by fastening together, or "laminating,"
several weaker layers of roofstrata to build a "beam."
Rooffall - A coalmine cave-in especially in permanent areas such as entries.
Roofjack - A screw- or pump-type hydraulic extension postmade of steel and
used as temporary roofsupport.
Roofsag - The sinking, bending, or curving of the roof, especially in the middle,
from weight or pressure.
Roofstress - Unbalanced internal forces in the roof or sides, created when coal is
extracted.

Roofsupport – Posts, jacks, roof bolts and beams used to supportthe rock
overlying a coal seam in an underground mine. A good roof supportplan is part of
mine safety and coal extraction.
Rooftrusses - A combination of steel rods anchored into the roof to create zones
of compressionand tension forces and provide better supportfor weak roofand
roof over wide areas.
Roomand pillar mining – A method of underground mining in which
approximately half of the coal is left in place to supportthe roof of the active
mining area. Large "pillars" are left while "rooms" of coal are extracted.
Roomneck - The short passage from the entry into a room.
Round - Planned pattern of drill holes fired in sequence in tunneling, shaft sinking,
or stopping. First the cut holes are fired, followed by relief, lifter, and rib holes.
Royalty - The payment of a certain stipulated sum on the mineral produced.
Rubbing surface - The total area (top, bottom, and sides) of an airway.
Run-of-mine - Raw material as it exists in the mine; average grade or quality.
S
Safetyfuse - A train of powder enclosed in cotton, jute yarn, or waterproofing
compounds, which burns at a uniform rate; used for firing a cap containing the
detonation compound which in turn sets off the explosive charge.
Safetylamp - A lamp with steel wire gauze covering every opening from the
inside to the outside so as to prevent the passage of flame should explosive gas be
encountered.
Sampling - Cutting a representative part of an ore (or coal) deposit, which should
truly represent its average value.
Sandstone - A sedimentary rock consisting of quartz sand united by some
cementing material, such as iron oxide or calcium carbonate.
Scaling - Removal of loose rock from the roof or walls. This work is dangerous
and a long bar (called a scaling bar)is often used.

Scoop- A rubber tired-, battery- or diesel-powered piece of equipment designed
for cleaning runways and hauling supplies.
Scrubber – Any of several forms of chemical/physical devices that remove sulfur
compounds formed during coal combustion. These devices, technically know as
flue gas desulfurization systems, combine the sulfur in gaseous emissions with
another chemical medium to form inert "sludge," which must then be removed for
disposal.
Seam- A stratum or bed of coal.
Secondaryroof - The roof strata immediately above the coalbed, requiring support
during the excavating of coal.
Section- A portion of the working area of a mine.
Selective mining - The object of selective mining is to obtain a relatively high-
grade mine product;this usually entails the use of a much more expensive stopping
system and high exploration and development costs in searching for and
developing the separate bunches, stringers, lenses, and bands of ore.
Self-containedbreathing apparatus - A self-contained supply of oxygen used
during rescue work from coal mine fires and explosions; same as SCSR (self-
contained self rescuer).
Self-rescuer– A small filtering device carried by a coal miner underground, either
on his belt or in his pocket, to provide him with immediate protection against
carbonmonoxide and smoke in case of a mine fire or explosion. It is a small
canister with a mouthpiece directly attached to it. The wearer breathes through the
mouth, the nosebeing closed by a clip. The canister contains a layer of fused
calcium chloride that absorbs water vapor from the mine air. The device is used for
escapepurposes only because it does not sustain life in atmospheres containing
deficient oxygen. The length of time a self-rescuer can be used is governed mainly
by the humidity in the mine air, usually between 30 minutes and one hour.
Severance – The separation of a mineral interest from other interests in the land by
grant or reservation. A mineral dead or grant of the land reserving a mineral
interest, by the landowner before leasing, accomplishes a severance as does his
execution of a mineral lease.

Shaft - A primary vertical or non-vertical opening through mine strata used for
ventilation or drainage and/or for hoisting of personnel or materials; connects the
surface with underground workings.
Shaft mine – An underground mine in which the main entry or access is by means
of a vertical shaft.
Shale - A rock formed by consolidation of clay, mud, or silt, having a laminated
structure and composedofminerals essentially unaltered since deposition.
Shearer- A mining machine for longwall faces that uses a rotating action to
"shear" the material from the face as it progresses along the face.
Shift - The number of hours or the part of any day worked.
Shortwall – An underground mining method in which small areas are worked (15
to 150 feet) by a continuous miner in conjunction with the use of hydraulic roof
supports.
Shuttle car– A self-discharging truck, generally with rubber tires or caterpillar-
type treads, used for receiving coal from the loading or mining machine and
transferring it to an underground loading point, mine railway or belt conveyor
system.
Sinking - The process bywhich a shaft is driven.
Skid - A track-mounted vehicle used to hold trips or cars from running out of
control. Also it is a flat-bottom personnel or equipment carrier used in low coal.
Skip - A car being hoisted from a slope or shaft.
Slack - Small coal; the finest-sized softcoal, usually less than one inch in
diameter.
Slag - The waste productof the process ofsmelting.
Slate - A miner's term for any shale or slate accompanying coal. Geologically, it is
a dense, fine-textured, metamorphic rock, which has excellent parallel cleavage so
that it breaks into thin plates or pencil-like shapes.

Slate bar - The proper long-handled tool used to pry down loose and hazardous
material from roof, face, and ribs.
Slickenside - A smooth, striated, polished surface produced on rockby friction.
Slip - A fault. A smoothjoint or crack where the strata have moved on each other.
Slope - Primary inclined opening, connection the surface with the underground
workings.
Slope mine – An underground mine with an opening that slopes upward or
downward to the coal seam.
Sloughing - The slow crumbling and falling away of material from roof, rib, and
face.
Solid - Mineral that has not been undermined, sheared out, or otherwise prepared
for blasting.
Sounding - Knocking on a roof to see whether it is sound and safe to work under.
Spad – A spad is a flat spike hammered into a wooden plug anchored in a hole
drilled into the mine ceiling from which is threaded a plumbline. The spad is an
underground survey station similar to the use of stakes in marking survey points on
the surface. A pointer spad, or sight spad, is a station that allows a mine foreman to
visually align entries or breaks from the main spad.
Span - The horizontal distance between the side supports orsolid abutments along
sides of a roadway.
Specific gravity - The weight of a substancecompared with the weight of an equal
volume of pure water at 4 degrees Celsius.
Split - Any division or branch of the ventilating current. Also, the workings
ventilated by one branch. Also, to divide a pillar by driving one or more roads
through it.
Squeeze - The settling, without breaking, of the roof and the gradual upheaval of
the floor of a mine due to the weight of the overlying strata.

Steeply inclined - Said of deposits and coal seams with a dip of from 0.7 to 1 rad
(40 degrees to 60 degrees).
Stemming - The noncombustible material used on top or in front of a charge or
explosive.
Strike - The direction of the line of intersection of a bed or vein with the
horizontal plane. The strike of a bed is the direction of a straight line that connects
two points of equal elevation on the bed.
Stripping ratio – The unit amount of overburden that must be removed to gain
access to a similar unit amount of coal or mineral material.
Stump - Any small pillar.
Subbituminous – Coal of a rank intermediate between lignite and bituminous.
Subsidence – The gradual sinking, or sometimes abrupt collapse, of the rock and
soil layers into an underground mine. Structures and surface features above the
subsidence area can be affected.
Sump - The bottom of a shaft, or any other place in a mine, that is used as a
collecting point for drainage water.
Sumping - To force the cutter bar of a machine into or under the coal. Also called
a sumping cut, or sumping in.
Support - The all-important function of keeping the mine workings open. As a
verb, it refers to this function; as a noun it refers to all the equipment and
materials--timber, roof bolts, concrete, steel, etc.--that are used to carry out this
function.
Surface mine – A mine in which the coal lies near the surface and can be extracted
by removing the covering layers of rockand soil.
Suspension- Weaker strata hanging from stronger, overlying strata by means of
roof bolts.
Syncline - A fold in rock in which the strata dip inward from both sides toward the
axis. The oppositeof anticline.

T
Tailgate - A subsidiary gate road to a conveyor face as opposed to a main gate.
The tailgate commonly acts as the return airway and supplies road to the face.
Tailpiece - Also known as foot section pulley. The pulley or roller in the tail or
foot section of a belt conveyor around which the belt runs.
Tail section- A term used in bothbelt and chain conveyor work to designate that
portion of the conveyor at the extreme oppositeend from the delivery point. In
either type of conveyor it consists of a frame and either a sprocketor a drum on
which the chain or belt travels, plus such other devices as may be required for
adjusting belt or chain tension.
Tension- The act of stretching.
Tertiary - Lateral or panel openings (e.g., ramp, crosscut).
Through-steel- A system of dustcollection from rockor roofdrilling. The drill
steel is hollow, and a vacuum is applied at the base, pulling the dust through the
steel and into a receptacle on the machine.
Timber - A collective term for underground woodensupports.
Timbering - The setting of timber supports in mine workings or shafts for
protection against falls from roof, face, or rib.
Timber set- A timber frame to supportthe roof, sides, and sometimes the floor of
mine roadways or shafts.
Tipple - Originally the place where the mine cars were tipped and emptied of their
coal, and still used in that same sense, although now more generally applied to the
surface structures of a mine, including the preparation plant and loading tracks.
Ton – A short or net ton is equal to 2,000 pounds;a long or British ton is 2,240
pounds;a metric ton is approximately 2,205 pounds.
Top - A mine roof; same as "back."
Torque wrench - A wrench that indicates, as on a dial, the amount of torque (in
units of foot-pounds)exerted in tightening a roofbolt.

Tractor- A battery-operated piece of equipment that pulls trailers, skids, or
personnel carriers. Also used for supplies.
Tram - Used in connection with moving self-propelled mining equipment. A
tramming motor may refer to an electric locomotive used for hauling loaded trips
or it may refer to the motor in a cutting machine that supplies the power for
moving or tramming the machine.
Transfer- A vertical or inclined connection between two or more levels and used
as an ore pass.
Transferpoint - Location in the materials handling system, either haulage or
hoisting, where bulk material is transferred between conveyances.
Trip - A train of mine cars.
Troughing idlers - The idlers, located on the upper framework of a belt conveyor,
which supportthe loaded belt. They are so mounted that the loaded belt forms a
trough in the direction of travel, which reduces spillage and increases the carrying
capacity of a belt for a given width.
Tunnel - A horizontal, or near-horizontal, underground passage, entry, or
haulageway, that is open to the surface at both ends. A tunnel (as opposedto an
adit) must pass completely through a hill or mountain.
U
Ultimate analysis - Precise determination, by chemical means, of the elements and
compounds in coal.
Undercut - To cut below or undermine the coal face by chipping away the coal by
pick or mining machine. In some localities the terms "undermine" or "underhole"
are used.
Underground mine – Also known as a "deep" mine. Usually located several
hundred feet below the earth's surface, an underground mine's coal is removed
mechanically and transferred by shuttle car or conveyor to the surface.
Underground station- An enlargement of an entry, drift, or level at a shaft at
which cages stop to receive and discharge cars, personnel, and material. An
underground station is any location where stationary electrical equipment is

installed. This includes pump rooms, compressorrooms, hoistrooms, battery-
charging rooms, etc.
Unit train – A long train of between 60 and 150 or more hopper cars, carrying
only coal between a single mine and destination.
Universal coalcutter - A type of coalcutting machine which is designed to make
horizontal cuts in a coal face at any point between the bottom and top or to make
shearing cuts at any point between the two ribs of the place. The cutter bar can be
twisted to make cuts at any angle to the horizontal or vertical.
Upcast shaft - A shaft through which air leaves the mine.
V
Valuation - The act or process ofvaluing or of estimating the value or worth;
appraisal.
Velocity - Rate of airflow in lineal feet per minute.
Ventilation - The provision of a directed flow of fresh and return air along all
underground roadways, traveling roads, workings, and service parts.
Violation - The breaking of any state or federal mining law.
Virgin - Unworked; untouched; often said of areas where there has been no coal
mining.
Void - A general term for pore spaceor other reopenings in rock. In addition to
pore space, the term includes vesicles, solution cavities, or any openings either
primary or secondary.
Volatile matter - The gaseous part, mostly hydrocarbons, ofcoal.
W
Waste - That rock or mineral which must be removed from a mine to keep the
mining scheme practical, but which has no value.
WaterGauge (standard U-tube) - Instrument that measures differential pressures
in inches of water.

Wedge - A piece of wood tapering to a thin edge and used for tightening in
conventional timbering.
Weight - Fracturing and lowering of the roofstrata at the face as a result of mining
operations, as in "taking weight".
White damp - Carbonmonoxide, CO. A gas that may be present in the afterdamp
of a gas- or coal-dust explosion, or in the gases given off by a mine fire; also one
of the constituents of the gases produced by blasting. Rarely found in mines under
other circumstances. It is absorbed by the hemoglobin of the blood to the exclusion
of oxygen. One-tenth of 1% (.001) may be fatal in 10 minutes.
Width - The thickness of a lode measured at right angles to the dip.
Winning - The excavation, loading, and removal of coal or ore from the ground;
winning follows development.
Winze - Secondary or tertiary vertical or near-vertical opening sunk from a point
inside a mine for the purposeof connecting with a lower level or of exploring the
ground for a limited depth below a level.
Wire rope - A steel wire rope used for winding in shafts and underground
haulages. Wire ropes are made from medium carbon steels. Various constructions
of wire rope are designated by the number of strands in the rope and the number of
wires in each strand. The following are some common terms encountered: airplane
strand; cablelaid rope; cane rope; elevator rope; extra-flexible hoisting rope; flat
rope; flattened-strand rope; guy rope; guy strand; hand rope; haulage rope; hawser;
hoisting rope; lang lay rope; lay; left lay rope; left twist; nonspinning rope; regular
lay; reverse-laid rope; rheostat rope; right lay; right twist; running rope; special
flexible hoisting rope; standing rope; towing hawser; transmission rope.
Working - When a coal seam is being squeezed by pressure from roof and floor, it
emits creaking noises and is said to be "working". This often serves as a warning to
the miners that additional supportis needed.
Working face - Any place in a mine where material is extracted during a mining
cycle.
Working place - From the outby side of the last open crosscutto the face.

Workings - The entire system of openings in a mine for the purposeof
exploitation.
Working section- From the faces to the point where coal is loaded onto belts or
rail cars to begin its trip to the outside.
BULK ROCKTERMS
Ore
a mineral or minerals that can be mined and extracted from a rock at a profit.
Gangue
Thoseminerals which occurwith the ore minerals but which have no value, such
as quartz, calcite or pyrite.
EVALUATION TERMS
Mineralization / Mineralisation
A general term which usually refers to ore minerals but which often may refer to
other metallic minerals such as pyrite.
Waste
Rockwhich is not ore.Usually referred to that rockwhich has to be removed
during the normal course of mining in order to get at the ore.
Grade
The concentration of each ore metal in a rock sample, usually given as weight
percent. If concentrations are extremely low, as with Au, Ag, Pt and others, the
concentration may be given in grams per tonne (g/t). The average grade of an ore
deposit is calculated, often employing very sophisticated statistical procedures, as
an average of the grades of a very large number of samples collected from
throughout the deposit.

Cut-off
The cut-off grade is the arbitrarily defined lowest grade which will be mined from
an ore deposit, and usually defines the boundary of the deposit. Forexample, if the
average grade of a porphyry deposit is 0.5% Cu, the cut-off might be 0.2% Cu. any
rock with a grade below 0.2% Cu would be waste.
Reserves
The amount of ore in a given deposit, usually quoted as the number of tonnes
available at a specific average grade.
DEPOSIT TERMS
Host rock
The rock within which the ore deposit occurs.
Country rock
The rock which surrounds the ore deposit. Also referred to as wall rock , in
particular that rock on either side of a vein.
Hydrothermal
Hot fluids, usually mainly water, sometimes acidic which may carry metals
andother compounds in solution to the site of ore deposition or wall rock alteration.
Alteration
A change in the mineralogy of the country rockas a result of a chemical reaction
with hydrothermal solutions. For example, mafic minerals such as hornblende or
biotite may alter to chlorite and feldspars may alter to clay. An alteration zone
describes rocks which have been altered to a specific group of secondary or
alteration minerals, usually around the perimeter of a mineral deposit.
Vein

A tabular depositusually formed by deposition of ore and gangue minerals in open
spaces within a fault or other structural environment.
Replacement
A chemical process whereby hydrothermal fluids, passing through permeable
rocks, react with the rocks to dissolve original minerals and relace them with
oreand/or other gangue minerals.
Massive sulphide
A stratiform (see below), usually lens-shaped mineral depositconsisting of at least
60% sulphide minerals.
Skarn
A replacement of limestone (calcium carbonate) or other carbonate-rich rocks
adjacent to an intrusive contact by calc-silicate minerals usually through the
addition of Si and other elements.
Epigenetic
Mineralization which has been deposited later than its immediate host rocks, for
example a vein. The ore is younger than the host rocks.
Syngenetic
Mineralization which has been deposited simultaneously with its hostrocks, for
example placer deposits. The ore is the same age as the host rocks.
Gossan
A rusty, surficial weathering zone which is caused by the oxidation of pyrite to
producesecondaryiron oxide minerals. Since pyrite is often associated with ore
deposits, gossans can be a guide to ore.
SHAPE OF THE DEPOSIT TERMS
Concordant
Any geologic body, such as an ore deposit, which lies within or parallel to
volcanic or sedimentary bedding and does not cut across the bedding structures.
(Also conformable ).

Discordant
A geologic body, such as a dike or vein, which cuts across primary rockstructures
such as bedding.
Stratiform
A mineral depositwhich occurs as a specific stratigraphic (or sedimentary) bed.
Stratabound
A mineral depositwhich occurs within a specific stratigraphic bed or horizon, but
which does not comprise the entire bed.
STRUCTURALTERMS
Footwall
The lower contactof an inclined vein, or the wall rock which lies on the lower side
of a dipping vein.
Hangingwall
The upper contactof an inclined vein.
Fault
A planar feature or fracture zone along which displacement has occurred.
Shearzone
A planar zone of weakness, similar to a fault, but consisting of several parallel
displacement zones usually over a greater width than a single fault.
Lode, shoot
All refer to mineralized zones within a fault or shear zone or a vein fissure, stringer
structure.
Breccia
Angular fragments of rock produced by movement along a fault or explosive
igneous activity. The material which surrounds the fragments and cements them
together is called matrix and might be vein minerals, igneous material or very fine
rock fragments.

Stockwork
A large number of small, closely spaced veins, often with many different
orientations, is referred to as a stockworkand sometimes as a stringer zone.
Chimney
Also referred to as a pipe , this is a vertically oriented, cylindrical body, often a
breccia, of vein or replacement mineralization.
Manto
This is a horizontally oriented chimney-like structure, usually of replacement
mineralization.
TEXTURAL TERMS
Banding
Banding may represent small scale sedimentary layering in a syngenetic deposit
such as a massive sulphide or repeated pulses of mineralization in a vein.
Crustiform banding
When minerals grow within a vein, they often grow inwards from the vein wall.
Several layers of different types of minerals, representing different pulses of often
aligned symmetrically away from the center of the vein.
Comb structure
When minerals crystallize inwards from oppositewalls of a vein, they often meet
in the center to form an interdigitating pattern of crystals, usually quartz, which has
an appearance similar to a rooster's comb.
Vug
This is an open spaceor cavity, usually within a vein.
Cockscomb

This is a crustiform banding when it surrounds breccia fragments.

Mining terminology

More Related Content

What's hot (20)

Viewers also liked (20)

Similar to Mining terminology (20)

More from Ghulam Mehdi (20)

Recently uploaded (20)

Mining terminology