Glossary of Mining Terms

Adit – A nearly horizontal passage from the surface by which a mine is entered and dewatered. A blind horizontal opening into a mountain, with only one entrance.

Angle of dip – The angle at which strata or mineral deposits are inclined to the horizontal plane.

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.

Backfill – Mine waste or rock used to support the roof after ore removal. (also known as paste when mixed with cement)

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.

Borehole – Any deep or long drill-hole, usually associated with a diamond drill.

Cage – In a mine shaft, the device, similar to an elevator car, that is used for hoisting personnel and materials.

Crosscut – A passageway driven between the entry and its parallel air course or air courses for ventilation purposes. Also, a tunnel driven from one seam to another through or across the intervening measures; sometimes called “crosscut tunnel”, 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.

Deposit – Mineral deposit or ore deposit is used to designate a natural occurrence of a useful mineral, or an ore, in sufficient extent and degree of concentration to invite exploitation.

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.

Drift – A horizontal passage underground. A drift follows the vein, as distinguished from a crosscut that intersects it, or a level or gallery, which may do either.

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.

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.

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 of mining and removal of or ore from a mine.

Face – The exposed area of a rock from which ore is being extracted.

Fissure – An extensive crack, break, or fracture in the rocks.

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.

Fracture – A general term to include any kind of discontinuity in a body of 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.

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).

Ground pressure – The pressure to which a rock formation is subjected by the weight of the superimposed rock and 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, such as casing or timber. 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.

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 ore or material.

Hopper – A bin or funnel that is loaded from the top and which discharges through a door or chute at the bottom.

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: Secondary inclined opening, driven upward to connect levels, sometimes on the dip of a deposit; also called “inclined shaft”.

Jackleg – A percussion drill used for drifting or stoping 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.

Laser Drill – A device using a High Power Laser connected to a Scan Head via Fiber Optic Cable used to drill or bore holes in geologic formations on the surface or underground.

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.

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 passage at 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.

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.

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 conduct of mining.

MSHA – Mine Safety and Health Administration; the federal agency which regulates coal mine health and safety.

Percussion drill – 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 accordance with 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.

Portal – The structure surrounding the immediate entrance to a mine; the mouth of an adit or tunnel.

Portal bus – Track-mounted, self-propelled personnel carrier that holds 8 to 12 people.

Ramp – A secondary or tertiary inclined opening, driven to connect levels, usually driven in a downward direction, and used for haulage.

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 stoping system and high exploration and development costs in searching for and developing the separate bunches, stringers, lenses, and bands of ore.

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 composed of minerals essentially unaltered since deposition.

Sinking – The process by which 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 mines.

Skip – A car being hoisted from a slope or shaft.

Slag – The waste product of the process of smelting.

Slickenside – A smooth, striated, polished surface produced on rock by friction.

Slip – A fault. A smooth joint 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 ore 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.

Spall - a chip or splinter, as of stone or ore or to break or split off in chips or bits.

Spiral Ramp – Inclined underground opening that connects levels of production areas. Ramps are inclined to allow the passage of motorized vehicles.

Stope – Underground excavation made by removing ore from surrounding rock. Stoping is the process of extracting the desired ore or other mineral from an underground mine, leaving behind an open space known as a stope. Stoping is used when the country rock is sufficiently strong not to cave into the stope, although in most cases artificial support is also provided.

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.

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.

Transfer point – Location in the materials handling system, either haulage or hoisting, where bulk material is transferred between conveyances.

Tunnel – A horizontal, or near-horizontal, underground passage, entry, or haulageway, that is open to the surface at both ends. A tunnel (as opposed to an adit) must pass completely through a hill or mountain.

Vein Miner - An array of Laser Drills and other ancillary equipment primarily used to remove material from the face of geologic formation that usually contains a precious metal ore.

Waste – That rock or mineral which must be removed from a mine to keep the mining scheme practical, but which has no value.

Width – The thickness of a lode measured at right angles to the dip.

Winze – Secondary or tertiary vertical or near-vertical opening sunk from a point inside a mine for the purpose of connecting with a lower level or of exploring the ground for a limited depth below a level.

Working face – Any place in a mine where material is extracted during a mining cycle.

Working place – From the out by side of the last open crosscut to the face.

Workings – The entire system of openings in a mine for the purpose of exploitation.

XRF - (X-ray Fluorescence spectrometry) A device for the detection of elemental metals.