Terms and Vocabulary



Abutment - (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 -  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 or chemical 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.


Acidic precipitation - Snow and rain that have a low pH, caused by sulphur dioxide and nitric oxide gases from industrial activity released into the atmosphere.

Acidic rocks - Igneous rock carrying a high (greater than 65%) proportion of silica.

Acid mine drainage - Acidic run-off water from mine waste dumps and mill tailings ponds containing sulphide minerals; also refers to ground water pumped to surface from mines.

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 passage opening driven horizontally into the side of a mountain or hill for providing access to a mineral deposit; a surface by which a mine is entered and de-watered; an opening driven horizontally into the side of a mountain or hill for providing access to a mineral deposit.

Advance - Mining in the same direction, or order of sequence; first mining as distinguished from retreat.

Aerial magnetometer - An instrument used to measure magnetic field strength from an airplane.

Aeromagnetic survey - A geophysical survey using a magnetometer aboard, or towed behind, an aircraft.

Agglomerate - A breccia composed largely or entirely of fragments of volcanic rocks.

Agglomeration - A method or family of processes which can by used in concentrating valuable minerals based on their adhesive properties.

Agitation - In metallurgy, the act or state of being stirred or shaken mechanically, sometimes accomplished by the introduction of compressed air.

Airborne survey - A survey made from an aircraft to obtain photographs, or measure magnetic properties, radioactivity, etc.

Air split - The division of a current of air into two or more parts.

Airway - Any passage through which air is carried. Also known as an air course.

Alloy - A compound of two or more metals.

Alluvial or Bench Deposits - An ancient river-washed rock and gravel bar that may be thousands of feet from the nearest stream, creek, or river. Alluvial or bench deposits contain untapped potential for finding gold because such areas have never been worked before. The hydraulic giants generally worked alluvial deposits.

Alluvium - Relatively recent deposits of sedimentary material; including loose gravel, laid down in river beds, flood plains, lakes, or at the base of mountain slopes. (adj. alluvial)

Alpha meter - An instrument used to measure positively charged particles emitted by radioactive materials.

Alpha ray - A positively charged particle emitted by certain radioactive materials.

Alteration - Any physical or chemical change in a rock or mineral subsequent to its formation. Milder and more localized than metamorphism.

Amalgam - Gold or silver combined with quicksilver.


Amalgamation - The technique of using mercury to attract small particles of crushed gold and join with them in an amalgam, or alloy. Gold may be recovered by distilling off the mercury.


Amorphous - A term applied to rocks or minerals that possess no definite crystal structure or form, such as amorphous carbon.

Amortization - The gradual and systematic writing off of a balance in an account over an appropriate period.

Amphibolite - A gneiss or schist largely made up of amphibole and plagioclase minerals.


Ancient Riverbed Claims - Gold found in beds of rivers now extinct.


Anemometer - Instrument for measuring air velocity.


ANFO - Acronym for ammonium nitrate and fuel oil, a mixture used as a blasting agent in many mines.

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


Angle of draw - 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.


Annual report - The formal financial statements and report on operations issued by a corporation to its shareholders after its fiscal year-end.

Anode - A rectangular plate of metal cast in a shape suitable for refining by the electrolytic process.

Anomaly - Any departure from the norm which may indicate the presence of mineralization in the underlying bedrock.

Anthracite coal - Of the four types of coal, anthracite is the hardest of the four, a black coal containing a high percentage of fixed carbon, a low percentage of volatile matter, and contains the highest heat value. It is almost pure carbon and is used mainly for home heating and cooking. In some developing countries, it is also used for industrial purposes.


Anthracite - A hard, black coal containing a high percentage of fixed carbon and a low percentage of volatile matter.

Anticline - An upward fold or arch of rock strata shaped like the crest of a wave.

Apex - The top or terminal edge of a vein on surface or its nearest point to the surface.

Aquifer - A water-bearing bed of porous rock, often sandstone.


Arastra - A mill, consisting of one or more large stones dragged around on a circular bed, used to grind ore.


Arching - Fracture processes around 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.


Argentiferous - Bearing or producing silver.


Ash - The inorganic residue remaining after ignition of coal.

Assay - A chemical test performed on a sample of ores or minerals to determine the amount of valuable metals contained.

Assay foot (metre, inch, centimetre) - The assay value multiplied by the number of feet, metres, inches, centimetres across which the sample is taken.

Assay map - Plan view of an area indicating assay values and locations of all samples taken on the property.


Assaying – Finding the percentage of a given metal in ore or bullion.


Assessment – Amount levied on capital stock.


Assessment work - The amount of work, specified by mining law, that must be performed each year in order to retain legal control of mining claims.

Auger — A rotary drill that uses a screw device to penetrate, break, and then transport the drilled material (coal).


Authorized capital - see capital stock.

Autogenous grinding - The process of grinding ore in a rotating cylinder using large pieces of the ore instead of conventional steel balls or rods.


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.


Back - The ceiling, roof, or upper part of any underground opening and mining cavity.

Backfill - (1) Waste material used to fill the void created by mining an orebody (2) Mine waste or rock used to support the roof after coal removal.


Background - Minor amounts of radioactivity due not to abnormal amounts of radioactive minerals nearby, but to cosmic rays and minor residual radioactivity in the vicinity.

Back sample - Rock chips collected from the roof or back of an underground opening for the purpose of determining grade.

Backwardation - A situation when the cash or spot price of a metal stands at a premium over the price of the metal for delivery at a forward date.

Balance sheet - A formal statement of the financial position of a company on a particular day, normally presented to shareholders once a year.

Ball mill - A steel cylinder filled with steel balls into which crushed ore is fed. The ball mill is rotated, causing the balls to cascade and grind the ore.

Banded iron formation - A bedded deposit of iron minerals.

Bar Claims – Gold found in in low collections of sand, or gravel, in rivers, exposed at low water.

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.

Barren Contract – A contract vein, or a place in the contract vein, which has no mineral.

Barricading - Enclosing part of a mine to prevent inflow of noxious gasses from a mine fire or an explosion.

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.

Basalt - An extrusive volcanic rock composed primarily of plagioclase, pyroxene and some olivine.

Basal till - Unsorted glacial debris at the base of the soil column where it comes into contact with the bedrock below.

Base Bullion – Precious metals contained in lead.

Basement rocks - The underlying or older rock mass. Often refers to rocks of Precambrian age which may be covered by younger rocks.

Base camp - Centre of operations from which exploration activity is conducted.

Base metal - Any non-precious metal (eg. copper, lead, zinc, nickel, etc.).

Basic rocks - Igneous rocks that are relatively low in silica and composed mostly of dark-colored minerals.|

Batholith - A large mass of igneous rock extending to great depth with its upper portion dome-like in shape. Similar, smaller masses of igneous rocks are known as bosses or plugs.

Bauxite - A rock made up of hydrous aluminum oxides; the most common aluminum ore.


Beam - A bar or straight girder used to support a span of roof between two support props or walls.


​Beam building - 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.

Bear market - Term used to describe market conditions when share prices are declining.

Bed/Bedding - The arrangement or stratum of sedimentary rocks in layers.

Bedrock – The formation underlying pay-dirt.

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 or guides 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 purpose is to automatically compensate for any slack in the belting created by start-up, etc.

Bench — One of to or more divisions of a mineral seam separated by slate; or formed by the process of cutting the coal.

Bench Claims – Minerals found in narrow tableland on hill-side, above a river.

Beneficiate - To concentrate or enrich; often applied to the preparation of iron ore for smelting.

Beneficiation — The treatment of mined material, making it more concentrated or richer.


Bentonite - A clay with great ability to absorb water and which swells accordingly.

Berm — A pile or mound of material capable of restraining a vehicle.

Bessemer - An iron ore with a very low phosphorus content.

Binder — A streak of impurity in a coal seam.

Bio-leaching - A process for recovering metals from low-grade ores by dissolving them in solution, the dissolution being aided

by bacterial action.

Biotite - A platy magnesium-iron mica, common in igneous rocks.

Bit - The cutting end of a drill frequently made of an extremely hard material such as industrial diamonds or tungsten carbide; 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." A general term descriptive of coal intermediate in rank between sub-bituminous and anthracite and including metallurgical coals. Low and medium volatile bituminous coals are ranked by their carbon content, while high volatile bituminous coals are ranked by their heating value.

Black damp - A term generally applied to carbon dioxide. Strictly speaking, it is a mixture of carbon dioxide and nitrogen. It is also applied to an atmosphere depleted of oxygen, rather than having an excess of carbon dioxide.

Blackjack - A miner's term for sphalerite (zinc sulphide).

Black smoker - Volcanic vent found in areas of active ocean floor spreading, through which sulphide-laden fluids escape.

Blaster - A mine employee responsible for loading, priming and detonating blastholes.

Blast furnace - A reaction vessel in which mixed charges of oxide ores, fluxes and fuels are blown with a continuous blast of hot air and oxygen-enriched air for the chemical reduction of metals to their metallic state.

Blasthole - A drill hole in a mine that is filled with explosives in order to blast loose a quantity of rock.

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.

Bleeder or 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.

Blende - An ore of zinc, consisting of zinc and sulphur.

Blind Lode - A lode having no outcrop.

Blister copper - A crude form of copper (assaying about 99%) produced in a smelter, which requires further refining before being used for industrial purposes.

Block caving - An inexpensive method of mining in which large blocks of ore are undercut, causing the ore to break or cave under its own weight.


​Blossom Rock - Float ore, found upon the surface or near where lodes or ledges outcrop, and from which they have become detached.


​Board lot - One hundred shares.

Boiler - A tank in which water is heated or steam is generated.

Bolt torque - The turning force in foot-pounds applied to a roof bolt to achieve an installed tension.

Bonanza - Fair weather; a mine said to en bonanza when it is yielding a profit. It is a Spanish term meaning good-luck.

Bond - An agreement to pay a certain amount of interest over a given period of time.

Boom - A telescoping, hydraulically powered steel arm on which drifters, manbaskets and hydraulic hammers are mounted.

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

Boss - Any member of the managerial ranks who is directly in charge of miners (e.g., "shift-boss," "face-boss," "fire-boss," etc.).

Bottom - Floor or underlying surface of an underground excavation.

Box hole - A short raise or opening driven above a drift for the purpose of drawing ore from a stope, or to permit access.

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 - Loosely used to describe a large-scale regional shear zone or structural fault.

Break line - The line that roughly follows the rear edges of mineral pillars that are being mined. The line along which the roof of a mine is expected to break.

Breaker - A machine which combines coal crushing and screening. Normally consists of a rotating drum in which coal is broken by gravity impact against the walls of the drum.

Breakthrough - A passage for ventilation that is cut through the pillars between rooms.

Breast - A working face in a mine, usually restricted to a stope.

Breasting Ore - Taking ore from the face, breast or end of a tunnel.

Breccia - A rock in which angular fragments are surrounded by a mass of fine-grained minerals.

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 boom of mining or lading machine or haulage system with the other end attached to a receiving bin that dollies along a frame supported by the room or entry conveyor, tailpiece. Thus, as the machine boom moves, the bridge conveyor keeps it in constant connection with the tailpiece.

Broken reserves - The ore in a mine which has been broken by blasting but which has not yet been transported to surface.

Brow - A low place in the roof of a mine, giving insufficient headroom.

Brunton compass - A pocket compass equipped with sights and a reflector, used for sighting lines, measuring dip and carrying out preliminary surveys.

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.

Bucket Line Dredge - Unlike modern dredges; a bucket line dredge was very large. Instead of sucking up water and gravel through the use of water pressure, the bucket line dredges would scoop it up and run it through a long sluice box.

Bug dust - The fine particles of minerals or other material resulting form the boring or cutting of the mineral face by drill or machine.

Bulk mining - Any large-scale, mechanized method of mining involving many thousands of tonnes of ore being brought to surface per day.

Bulk sample - A large sample of mineralized rock, frequently hundreds of tonnes, selected in such a manner as to be representative of the potential orebody being sampled. Used to determine metallurgical characteristics.

Bullion - Precious metals, gold and silver, etc./Metals formed into bars or ingots (not coined).

Bull market - Term used to describe financial market conditions when share prices are going up.

Bull quartz - A prospector's term for white, coarse-grained, barren quartz.

Butt cleat - A short, poorly defined vertical cleavage plane in a mineral seam, usually at right angles to the long face cleat.

Butt entry - A 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 mineral cleavage (that is, at right angles to the face).

Byproduct - A secondary metal or mineral product recovered in the milling process.



Cable bolt - A steel cable, capable of withstanding tens of tonnes, cemented into a drillhole to lend support in blocky ground.


Cage - In a mine shaft, the device, similar to an elevator car, that is used for hoisting personnel and materials; the conveyance used to transport men and equipment between the surface and the mine levels; the elevator used for hoisting and lowering the ore cars, men and materials of a mine.


Calcine - Name given to concentrate that is ready for smelting (i.e. the sulphur has been driven off by oxidation).


Call - An option to buy shares at a specified price. The opposite of a "put".


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.

Capitalization - A financial term used to describe the value financial markets put on a company. Determined by multiplying the number of outstanding shares of a company by the current stock price.


Capital stock - The total ownership of a limited liability company divided among a specified number of shares.


Cap Rock – Formation overlaying the ore or vein stone.

Captive stope - A stope that is accessible only through a manway.


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, made by fusing an insert of molded tungsten carbide to the cutting edge of a steel bit shank.

Carbonate - A geological formation which carries silver ore, and from 5 to 70 per cent. of lead.

Carbon Dioxide - A colorless, odorless, non-toxic radiative gas that is essential to plant and animal life. It is also emitted as a result of burning organic materials, including fossil fuels.

Carboniferous - Containing coal.

Carbon-in-pulp - A method of recovering gold and silver from pregnant cyanide solutions by adsorbing the precious metals to granules of activated carbon, which are typically ground up coconut shells.


Cash flow - The net of the inflow and outflow of cash during an accounting period. Does not account for depreciation or bookkeeping write-offs which do not involve an actual cash outlay.


Cast - A directed throw; in strip-mining, the overburden is cast from the mineral to the previously mined area.

Cathode - A rectangular plate of metal, produced by electrolytic refining, which is melted into commercial shapes such as wirebars, billets, ingots, etc.



Certified - Describes a person who has passed an examination to do a required job.



​Cesium magnetometer - An geophysical instrument which measures magnetic field strength in terms of vertical gradient and total field.


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 mineral/coal left to protect the gangway or entry and the parallel airways.

Chalcocite - A sulphide mineral of copper common in the zone of secondary enrichment.


Chalcopyrite - A sulphide mineral of copper and iron; the most important ore mineral of copper.


Change house - The mine building where workers change into work clothes; also known as the "dry".

Channel sample - A sample composed of pieces of vein or mineral deposit that have been cut out of a small trench or channel, usually about 10 cm wide and 2 cm deep.


Charcoal - The residue, primarily carbon, from the partial combustion of wood or other organic matter.

Charter - A document issued by a governing authority creating a company or other corporation.


Chartered bank - A financial institution that accepts deposits and provides loans.


Check curtain - Sheet of brattice cloth hung across an airway to control the passage of the air current.

Chilean Mill - A machine, somewhat like the arastra, in which heavy stone wheels turn about a central shaft and crush ore.

Chip sample - A method of sampling a rock exposure whereby a regular series of small chips of rock is broken off along a line across the face.


Chlorofluorocarbons (CFCs) - Human-produced chemical compounds containing chlorine, fluorine and carbon which are thought to be responsible for ozone-layer depletion. CFCs also act as a radiative gas.

Chock - Large hydraulic jacks used to support roof in longwall and shortwall mining systems.


Chlorides - A compound of chlorine and silver.

Chopping - The rock that appears on the surface indicating the presence of a lode.

Chromite - The chief ore mineral of chromium.


Chute - An opening, usually constructed of timber and equipped with a gate, through which ore is drawn from a stope into mine cars.; an inclined channel through which ore slides.


Cinnabar - A vermilion-colored ore mineral of mercury.


Circulating load - Over-sized chunks of ore returned to the head of a closed grinding circuit before going on to the next stage of treatment.


Claim - A portion of land held either by a prospector or a mining company. In Canada, the common size is 1,320 ft. (about 400 m) square, or 40 acres (about 16 ha); a piece of land 25 to 300 feet wide and 1,500 feet long, which the government sells to the man who finds mineral within its limits.


Clarification - Process of clearing dirty water by removing suspended material.


Classifier - A mineral-processing machine which separates minerals according to size and density.


Clay - A fine-grained material composed of hydrous aluminum silicates.


Clay vein - A body of clay-like material that fills a void in a coal bed.

Clean Air 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.

Clean Coal Technologies - 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 coal gasification.

Cleat - The vertical cleavage of coal seams. The main set of joints along which mineral/coal breaks when mined.

Cleavage - The tendency of a mineral to split along crystallographic planes.


Closed circuit - A loop in the milling process wherein a selected portion of the product of a machine is returned to the head of the machine for finishing to required specification.

Coal - A carbonaceous rock mined for use as a fuel.; 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.


Coal desulphurisation - Removal of sulphur from coal or coal gas.


Coal dust - Particles of coal that can pass a No. 20 sieve.


Coal Gasification - The conversion of coal into a gaseous fuel.

Coalification - The metamorphic processes of forming coal.


Coal mine - 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".

Coal reserves - Measured tonnages of coal that have been calculated to occur in a coal seam within a particular property.

Coal washing - The process of separating 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 substance produced by heating coal to a very high temperature in the absence of air. Coke is used in the manufacture of iron and steel.

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; also used to describe the top of a mill hole.


Colliery - British name for coal mine.

Column flotation - A milling process, carried out in a tall cylindrical column, whereby valuable minerals are separated from gangue minerals based on their wetability properties; A precombustion coal cleaning technology in which coal particles attach to air bubbles rising in a vertical column. The coal is then removed at the top of the column.


Combustion chamber - The part of a boiler in which fuel is burned.

Comminution - The breaking, crushing, or grinding of coal, ore, or rock.

Common stock - Shares in a company which have full voting rights which the holders use to control the company in common with each other. There is no fixed or assured dividend as with preferred shares, which have first claim on the distribution of a company's earnings or assets.

Competent rock - Rock which, 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).

Complex ore - An ore containing a number of minerals of economic value. The term often implies that there are metallurgical difficulties in liberating and separating the valuable metals.

Cone crusher - A machine which crushes ore between a gyrating cone or crushing head and an inverted, truncated cone known as a bowl.

Concentrate - A fine, powdery product of the milling process containing a high percentage of valuable metal.

Concentrator - A milling plant that produces a concentrate of the valuable minerals or metals. Further treatment is required to recover the pure metal.

Confirmation - A form delivered by a broker to the client, setting forth the details of stock sales or purchases for the client.

Conglomerate - A sedimentary rock consisting of rounded, water-worn pebbles or boulders cemented into a solid mass; pudding stones, composed of gravel and pebble cemented together.


Contact - A geological term used to describe the line or plane along which two different rock formations meet; 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; a touching, meeting or junction of two different kinds of rock, a porphyry and slate.


Contact metamorphism - Metamorphism of country rocks adjacent to an intrusion, caused by heat from the intrusion.


Contact Vein – A vein along the contact plane of, or between, two dissimilar rock masses.

Contango - A situation in which the price of a metal for forward or future delivery stands at a premium over the cash or spot price of the metal.

Continuous miner - A piece of mining equipment which produces a continuous flow of ore from the working face; A machine that constantly extracts coal while it loads it. 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.


Controlled blasting - Blasting patterns and sequences designed to achieve a particular objective. Cast blasting, where the muck pile is cast in a particular direction, and deck blasting, where holes are loaded once but blasted in successive blasts days apart, are examples.

Conventional mining - The first fully-mechanized underground mining method involving the insertion of explosives in a coal seam, the blasting of the seam, and the removal of the coal onto a conveyor or shuttle car by a loading machine.


Converter - In copper smelting, a furnace used to separate copper metal from matte.

Conveyor - An apparatus for moving material from one point to another in a continuous fashion. This is accomplished with an endless (that is, looped) procession of hooks, buckets, wide rubber belt, etc.


Core - The long cylindrical piece of rock, about an inch in diameter, brought to surface by diamond drilling.

Core barrel - That part of a string of tools in a diamond drill hole in which the core specimen is collected.

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.


Cordillera - The continuous chain of mountain ranges on the western margin of North and South America.

Cord of Ore - 128 cubic feet of broken ore; about seven tons in quartz rock.


Cornish Pump - A type of pump developed in Cornwall, England, and commonly used in deep mines of the nineteenth century to raise underground water.


Country rock - Loosely used to describe the general mass of rock adjacent to an orebody; rock on either side of a lode or ledge, usually barren; the permanent rock enclosing a vein; also known as the host rock


Cover - The overburden of any deposit.


Creep - The forcing of pillars into soft bottom by the weight of a strong roof. In surface mining, a very slow movement of slopes downhill.


Crib - A roof support of 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 chock or cog.


Cribbing - The construction of cribs or timbers laid at right angles to each other, sometimes filled with earth, as a roof support or as a support for 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 horizontal opening driven from a shaft and (or near) right angles to the strike of a vein or other orebody; A passageway driven between the entry and its parallel air course or air courses for ventilation purposes; 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; a horizontal tunnel driven perpendicular to the main direction of a 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.


Crust - The outermost layer of the Earth; includes both continental and oceanic crust.

Cum-dividend - Buyer entitled to pending dividend payment.

Current assets - Assets of company which can and are likely to be converted into cash within a year. Includes cash, marketable securities, accounts receivable and supplies.

Current liabilities - A company's debts that are payable within a year's time.

Custom smelter - A smelter which processes concentrates from independent mines. Concentrates may be purchased or the smelter may be contracted to do the processing for the independent company.

Cut-and-fill - A method of stoping in which ore is removed in slices, or lifts, and then the excavation is filled with rock or other waste material (backfill), before the subsequent slice is extracted.

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.


Cut value - Applies to assays that have been reduced to some arbitrary maximum to prevent erratic high values from inflating the average.

Cyanidation - A method of extracting exposed gold or silver grains from crushed or ground ore by dissolving it in a weak cyanide solution. May be carried out in tanks inside a mill or in heaps of ore out of doors.

Cyanide - A chemical species containing carbon and nitrogen used to dissolve gold and silver from ore.

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 support is established in the previous working face.


Day order - An order to buy or sell shares, good only on the day the order was entered.

Debenture - See bonds.

​Debris - Sediment from mines.

Debt financing - Method of raising capital whereby companies borrow money from a lending institution.

Deck - The area around the shaft collar where men and materials enter the cage to be lowered underground.

Decline - A sloping underground opening for machine access from level to level or from surface; also called a ramp.

Deferred charges - Expenses incurred but not charged against the current year's operation.

Demonstrated reserves - A collective term for the sum of coal in both measured and indicated resources and reserves.

Denudation - Rocks laid bare by running water or other agencies.

Depletion - An accounting device, used primarily in tax computations. It recognizes the consumption of an ore deposit, a mine's principal asset.

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.

Depreciation - The periodic, systematic charging to expense of plant assets reflecting the decline in economic potential of the assets.

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.

Development - Underground work carried out for the purpose of opening up a mineral deposit. Includes shaft sinking, crosscutting, drifting and raising.

Development drilling - drilling to establish accurate estimates of mineral reserves.

Development mining - Work undertaken to open up coal reserves as distinguished from the work of actual coal extraction.

​​Diabase - A common basic igneous rock usually occurring in dykes or sills.

Diamond - The hardest known mineral, composed of pure carbon; low-quality diamonds are used to make bits for diamond drilling in rock.

Diamond drill - A rotary type of rock drill that cuts a core of rock that is recovered in long cylindrical sections, two cm or more in diameter.

Diamond driller - A person who operates a diamond drill.

​​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.

Diggings - Name applied to placers being worked.

Dilute - To lower the concentration of a mixture; in this case the concentration of any hazardous gas in mine air by addition of fresh intake air.

Dilution - The contamination of ore with barren wall rock in stoping.

Dilution (mining) - Rock that is , by necessity, removed along with the ore in the mining process, subsequently lowering the grade of the ore.

Dilution (of shares) - A decrease in the value of a company's shares caused by the issue of treasury shares.

Diluvium - A deposit of superficial sand, loam, gravel, pebbles, etc.

Diorite - An intrusive igneous rock composed chiefly of sodic plagioclase, hornblende, biotite or pyroxene.

Dip - (1) The angle at which a vein, structure or rock bed is inclined from the horizontal as measured at right angles to the strike. (2) The inclination of a geologic structure (bed, vein, fault, etc.) from the horizontal; dip is always measured downwards at right angles to the strike.

​Dip needle - A compass with the needle mounted so as to swing in a vertical plane, used for prospecting to determine the magnetic attraction of rocks.

Directional drilling - A method of drilling involving the use of stabilizers and wedges to direct the orientation of the hole.

Discount - The minimum price below the par value at which treasury shares may legally be sold.

Disseminated ore - Ore carrying small particles of valuable minerals spread more or less uniformly through the host rock.

Dividend - Cash or stock awarded to preferred and common shareholders at the discretion of the company's board of directors.

Dividend claim - Made when a dividend has been paid to the previous holder because stock has not yet been transferred to the name of the new owner.


​Dor bar - The final saleable product of a gold mine. Usually consisting of gold and silver.


Drag fold - The result of the plastic deformation of a rock unit where it has been folded or bent back on itself.

Dragline - A large excavation machine used in surface mining to remove overburden (layers of rock and soil) covering a mineral 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 of removing surplus ground or surface water either by artificial means or by gravity flow.

Drawpoint - An underground opening at the bottom of a stope through which broken ore from the stope is extracted.

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 support is withdrawn.

Dredge - A common piece of mining equipment, the dredge sucks up dirt and gravel from within a stream bed by the use of water pressure.

Drift - (1) A horizontal underground opening/passage that follows along the length of a vein or rock formation as opposed to a crosscut which crosses the rock formation. (2) A horizontal passage underground that is .excavated along a rich vein of ore. Used in hard rock mining.

Drifter - A hydraulic rock drill used to drill small-diameter holes for blasting or for installing rock bolts.

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.

Drill-indicated reserves - The size and quality of a potential orebody as suggested by widely spaced drillholes; more work is required before reserves can be classified as probable or proven.

Dry - A building where the miner changes into working clothes.

​Dry Diggings - Earth excavated in the summer and held to be washed in winter, when water was more plentiful.

Dry Washing - Fine soil blown away, leaving the gold.

Drywasher - A common desert mining tool similar to a highbanker but doesn’t need water. It operates by the use of wind. The light junk material is blown off the top of the sluice in the drywasher and the gold

Due diligence - The degree of care and caution required before making a decision; loosely, a financial and technical investigation to determine whether an investment is sound.

Dummy - A bag filled with sand, clay, etc., used for stemming a charged hole.

Dump - (1) A pile of broken rock or ore on surface. (2) To unload; specifically, a load of mineral 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.). (3) The pile of ore or debris taken from mines, or tailings from sluicing.


Dyke - A long and relatively thin body of igneous rock that, while in the molten state, intruded a fissure in older rocks.


To Be Continued.....

The Miners Table

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The Miners Table