Mining Glossary

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Acidic rocks - Igneous rock carrying a high (greater than 65%) proportion of silica.
Adit - A horizontal passage from the surface into a mine. Sometimes called a tunnel.
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 of concentrating valuable minerals based on their adhesion 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.
Alloy - A compound of two or more metals.
Alluvium - Deposit of sedimentary material laid down in river beds, lakes, flood plains or at the base of mountain slopes.
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.
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.
ANFO - Acronym for ammonium nitrate and fuel oil, a mixture used as a blasting agent in many mines.
Anode - A rectangular plate of metal cast in a shape suitable for refining by the electrolytic process.
Anomaly - A geological feature, especially in the subsurface, distinguished by geological, geophysical, or geochemical means, which is different from the general surroundings, often of potential economic value and usually suggesting the possibility of a mineral deposit.
Anthracite - A hard, black coal containing a high percentage of fixed carbon and a low percentage of volatile matter.
Anticline - An arch or fold in layers of rock 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.
Argillic - Pertaining to clay or clay minerals; e.g. "argillic alteration", in which certain minerals of a rock are converted to minerals of the clay group.
Arsenopyrite - A tin-white or silver-white to steel-gray mineral. Arsenopyrite occurs chiefly in crystalline rocks and especially in lead and silver veins and constitutes the principal ore of arsenic.
Assay - To analyze the proportions of metals in an ore, to test an ore or mineral for composition, purity, weight or other properties of commercial interest.
Assay map - Plan view of an area indicating assay values and locations of all samples taken on the property.
Assessment work - The amount of work specified under mining law, that must be performed each year in order to retain legal control of mining claims.
Autogenous grinding - The process of grinding ore in a rotating cylinder using large pieces of the ore instead of conventional steel balls or rods.

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Back - The ceiling or roof of an underground opening.
Backfill - Waste material used to fill the void created by mining.
Backfilling - The process of refilling an excavation, a mine opening, or the space around a foundation.
Back sample - Rock samples collected from an excavated area 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.
Ball Mill - A rotating horizontal cylinder with a diameter almost equal to the length supported by a frame or shaft, in which nonmetallic materials are ground using various types of grinding media such as quartz pebbles, porcelain balls, etc.
Banded iron formation - A bedded deposit of iron minerals.
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.
Basement rocks - The underlying or older rock mass. Often refers to rocks of Precambrian age, which may be covered by younger rocks.
Base Metal - Any of the more common and more chemically active metals, e.g. lead, copper.
- The principal metal of an alloy, e.g. the copper in brass.
- Also commonly referred to as being the non-precious metals that are traded on the London Metal Exchange.
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 in dome-like shape.
Bauxite - A rock made up of hydrous aluminum oxides, the most common aluminum ore.
Bed/Beds - Common term in geology, meaning layer or stratum. Quarrymen usually mean by beds not the stone beds in the geologist's sense, but the partings between them.
Bedding - The arrangement of sedimentary rocks in layers.
Below Collar - A distance below the surface elevation of a shaft.
Bessemer - An iron ore with a very low phosphorus content.
Bio-leaching - A process for recovering metals from low-grade ores by dissolving them in solution, with dissolution 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.
Bench - In an underground mine, a long horizontal face or ledge of ore in a stope or working place.
Bench - In an underground mine, a long horizontal face or ledge of ore in a stope or working place. The horizontal step or floor along which coal, ore, stone, or overburden is worked or quarried.
Blaster - A mine employee responsible for loading, priming and detonating blastholes.
Blast-hole - A hole drilled in a material to be blasted, for the purpose of containing an explosive charge.
Breccia - A course-grained clastic rock, composed of angular broken rock fragments held together by a mineral cement or in a fine-grained matrix. The fragments have sharp edges and unworn corners.
Brunton compass - A pocket compass equipped with sights and a reflector, used for sighting lines, measuring dip and carrying out preliminary surveys.
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 - Metal formed into bars or ingots.
By-product - A secondary metal or mineral product recovered in the milling process.

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Cable bolt - A steel cable, capable of withstanding tens of tonnes, cemented into a drillhole to lend support in blocky ground.
Cage - The conveyance used to transport men and equipment between the surface and the mine levels.
Calcine - Name given to concentrate that is ready for smelting (i.e. the sulphur has been driven off by oxidation).
Calc-silicate rock - A metamorphic rock consisting mainly of calcium-bearing silicates, such as diopside and wollastonite, and formed by metamorphism of impure limestone or dolomite.
Call factor - The fraction of an ore reserve that is successfully mined.
Capital assets - Assets, purchased as a long term investment for generating profit, such as buildings, plant and machinery and fixtures etc.
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.
Carat - The unit of weight for gemstones (one carat weighs 200 mg).
- The unit of purity for gold jewelry (one gold carat is 1/24 part gold, 23/24 parts other metals). Pure gold has 24 carats.
Carbon columns - Any vertical cylindrical vessels used to contain granules of activated carbon for processes such as the extraction of gold from solution, elution or acid treatment.
Carbon-in-leach - A recovery process in which a slurry of gold ore, carbon granules and cyanide are mixed together. The cyanide dissolves the gold content and the gold is absorbed on the carbon: the carbon is subsequently separated from the slurry for further gold removal.
Carbon-in-pulp - A precious metals leaching technique in which granular activated carbon particles much larger than the ground ore particles are added to the cyanidation pulp after the precious metals have been solubilized. The activated carbon and pulp are agitated together to enable the solubilized precious metals to become absorbed onto the activated carbon. The loaded activated carbon is mechanically screened to separate it from the barren ore pulp and processed to remove the precious metals and prepare it for reuse. Similar to carbon-in-leach process.
Carbonaceous - Said of a rock or sediment that is rich in carbon; coaly.
- Said of a sediment containing organic matter.
Carbonate - A mineral compound characterized by a fundamental anionic structure.
Carbonate - A mineral compound characterized by a fundamental anionic structure.
- A sediment formed by the organic or inorganic precipitation from aqueous solution of carbonates of calcium, magnesium, or iron; e.g. limestone and dolomite.
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.
Cash operating cost - Include site costs for all mining (excluding deferred stripping costs), processing and administration, but are exclusive of royalties, production taxes, depreciation, reclamation, financing costs, capital costs and exploration costs.
Cathode - A rectangular plate of metal, produced by electrolytic refining, which is melted into commercial shapes such as wirebars, billets, ingots, etc.
Chalcopyrite - A bright brass-yellow tetragonal mineral. It is generally found massive and constitutes the most important ore of copper.
Channel sample - A sample composed of pieces of vein or mineral deposit that have been cut out of a small trench or channel, usually 10 cm wide and 2 cm deep.
Channel width - The total thickness of all reef bands, including internal waste mined as one unit.
CIL - Carbon-in-leach process, which integrates leaching and carbon-in-pulp into a single unit process operation.
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.
Chute - An opening, usually constructed of timber and equipped with a gate, through which ore is drawn from a stope into mine cars.
Collar - The mouth or upper end of a mineshaft.
Column flotation - A milling process, carried out in a cylindrical column, whereby valuable minerals are separated from gangue minerals based on their wetability properties.
Compression - A system of forces or stresses that tends to decrease the volume of a substance, or the change of volume produced by such a system of forces.
Concentrates - The valuable fraction of an ore that is left after worthless material is removed in processing.
Concentrator - A plant where ore is separated into values (concentrates) and rejects (tails). An appliance in such a plant (flotation cell, jig, electromagnet, shaking table) in which, by the aid of water, air, and/or gravity, mechanical concentration of ores is performed. Also called mill; reduction works; cleaning plant.
Cone crusher - A machine which crushes ore between a gyrating cone (crushing head) and an inverted, truncated cone (bowl).
Conglomerate - A sedimentary rock consisting of rounded, water-worn pebbles or boulders cemented into a solid mass.
Contact - A geological term used to describe the line or plane along which two different rock formations meet.
Contact metamorphism - Metamorphism of country rocks adjacent to an intrusion, caused by heat from the intrusion.
Contained gold - The total gold content of the orebody (tons multiplied by grade), irrespective of economic potential and without deduction for mining and processing losses prior to recovery.
Contained ounces - Represents ounces in the ground without the reduction of ounces not recovered by the applicable metallurgical process.
Core - The long cylindrical piece of rock, usually 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 Hole - Any hole drilled for the purpose of obtaining cores.
Crosscut - A horizontal opening driven from a shaft at (or near) right angles to the strike of a vein or other orebody.
Crust - The outermost layer of the Earth; includes both continental and oceanic crust.
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 stoping method in which the ore is excavated by successive flat or inclined slices, working upward from the level. However, after each slice is blasted down, all broken ore is removed, and the stope is filled with waste (backfill) up to within a few feet of the back before the next slice is taken out, just enough room being left between the top of the waste pile and the back of the stope to provide working space. The term cut and fill stoping implies a definite and characteristic sequence of operations: breaking a slice of ore from the back, removing the broken ore and introducing filling.
Cut-off grade - The lowest grade of mineralized material that qualifies as ore in a given deposit; ore of the lowest assay value that is included in an ore estimate.
Cut value - A chosen maximum grade for cutting assays, used in order to prevent erratic high values from inflating the average.
Cyanidation - A process of extracting gold and silver as cyanide slimes from their ores by treatment with dilute solutions of potassium cyanide or sodium cyanide. The slimes are subsequently fused and cast into ingots or bullion.
Cyanide - A chemical species containing carbon and nitrogen used to dissolve gold and silver from ore.

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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 stripping costs - Mining costs associated with waste rock removal that are deferred and charged to income on the basis of the average stripping ratio for the mine. The average stripping ratio is calculated as a ratio of the tons of material estimated to be mined to the estimated recoverable ounces of gold. At the start of a mine's productive life costs on a per-ounce basis are usually higher than in later years, as the mining rate is above the life-of-mine stripping ratio. In later years, as the mining rate falls below the life-of-mine stripping ratio, the deferred costs are charged to operating costs.
Depletion - The decrease in quantity of ore in a deposit or property resulting from extraction or production.
Deposit - A body of rock containing a concentration of minerals.
Depreciation - The periodic, systematic charging to expense of plant assets reflecting the decline in economic potential of the assets.
Development - The preparation of a mining property or area so that an orebody can be analyzed and its tonnage and quality estimates have been made; ore essentially ready for mining.
- Underground work carried out for the purpose of opening up a mineral deposit. Includes shaft sinking, crosscutting, drifting and raising.
Diamond - The hardest known mineral, composed of pure carbon; low-quality diamonds are used to make bits for diamond drilling in rock.
Diamond drilling - A variety of rotary drilling in which diamond bits are used as the rock-cutting tool. It is a common method of prospecting for mineral deposits, especially in development work where core samples are desired.
Dilution (mining) - The necessary mining of waste rock, along with ore. Measured as the ratio of waste rock to the total amount of rock mined.
- The contamination of ore with barren wall rock in stoping. The assay of the ore after mining is frequently 10% lower than when sampled in place.
Dike - A tabular igneous intrusion that cuts across the bedding or foliation of the country rock.
Dike swarm - A group of dikes, which may be in radial, parallel, or en echelon arrangement. Their relationship with the parent plutonic body may not be directly observable.
Diorite - An igneous rock formed by the solidification of molten material.
Dip - The angle at which a vein, structure or rock bed is inclined from the horizontal, as measured at right angles to the strike.
Directional drilling - A method of drilling involving the use of stabilizers and wedges to direct the orientation of the hole.
Disseminated ore - Said of a mineral deposit (especially of metals) in which the desired minerals occur as scattered particles in the rock, but in sufficient quantity to make the deposit an ore.
Dor bar - The final saleable product of a gold mine. Usually consisting of gold and silver.
Doré - Gold and silver bullion that remains in a cupelling furnace after the lead has been oxidized and skimmed off.
Drag fold - The result of the plastic deformation of a rock unit where it has been folded or bent back on itself.
Drawpoint - An underground opening at the bottom of a stope through which broken ore from the stope is extracted.
Drift - A horizontal or nearly horizontal underground opening driven along a vein to gain access to the deposit.
Drifter - A hydraulic rock drill used to drill small-diameter holes for blasting or for installing rock bolts.
Dry stack tailings - Dewatering tailings to higher degrees than a paste consistency. This produces a dry (unsaturated) cake that can no longer be transported by pipeline due to its low moisture content. This method of storing tailings is considered to reduce the environmental impacts.
Dump - A pile of broken rock or ore on surface.
Dyke - A long and relatively thin body of igneous rock that, while in the molten state, intruded a fissure in older rocks.

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Electrolysis - An electric current is passed through a solution containing dissolved metals, causing the metals to be deposited onto a cathode.
Electrolytic refining - The process of purifying metal ingots that are suspended as anodes in an electrolytic bath, alternated with refined sheets of the same metal which act as starters or cathodes.
Electro-winning - A process of recovering gold from solution by means of electrolytic chemical reaction into a form that can be smelted easily into gold bars.
Electrum - A naturally occurring, deep-yellow to pale-yellow alloy of gold with silver; argentiferous gold, containing more than 20% silver.
Elution - Recovery of the gold from the activated carbon into solution before zinc precipitation or electrowinning.
EM survey - A geophysical survey method which measures the electromagnetic properties of rocks.
En echelon - Roughly parallel but staggered structures.
Environmental impact study - A written report, compiled prior to a production decision, that examines the effects proposed mining activities will have on the natural surroundings.
EPCM - Engineering, procurement and construction management.
Epigenetic - Orebodies formed by hydrothermal fluids and gases that were introduced into the host rocks from elsewhere, filling cavities in the host rock.
Epithermal deposit - A mineral deposit consisting of veins and replacement bodies, usually in volcanic or sedimentary rocks, containing precious metals or, more rarely, base metals.
Erosion/ erosional - The group of physical and chemical processes by which earth or rock material is loosened or dissolved and removed from any part of the Earth's surface. It includes the processes of weathering, solution, corrosion, and transportation.
Exploration - Prospecting, sampling, mapping, diamond drilling and other work involved in searching for ore.
Extraction - The process of dissolving and separating out specific constituents of a sample by treatment with solvents specific for those constituents.

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Face - The end of a drift, crosscut or stope in which work is taking place.
Fault - A break in the Earth's crust caused by tectonic forces which have moved the rock on one side with respect to the other.
Fault gouge - Soft, un-cemented pulverized clay or claylike material, commonly a mixture of minerals in finely divided form, found along some faults or between the walls of a fault, and filling or partly filling a fault zone. It is formed by the crushing and grinding of rock material as the fault developed, as well as by subsequent decomposition and alteration caused by underground circulating solutions.
Fault zone - A fault that is expressed as a zone of numerous small fractures or of breccia or fault gouge. A fault zone may be as wide as hundreds of meters.
Feasibility study - An economic study assessing whether a mineral deposit can be mined profitably.
Feldspar - A group of common rock-forming minerals that includes microcline, orthoclase, plagioclase and others.
Felsic - Term used to describe light-colored rocks containing feldspar, feldspathoids and silica.
Fill - Man-made deposits of natural earth materials (e.g. rock, soil, gravel) and waste materials (e.g. tailings or spoil from dredging), used to fill an enclosed space such as an old stope or chamber in a mine.
Fine gold - Fineness is the proportion of pure gold or silver in jewelry or bullion expressed in parts per thousand. Thus, 925 fine gold indicates 925 parts out of 1,000, or 92.5% is pure gold.
Fissure - An extensive crack, break or fracture in rocks.
Float - Pieces of rock that have been broken off and moved from their original location by natural forces such as frost or glacial action.
Flotation - A process by which some mineral particles are induced to become attached to bubbles and float, and other particles to sink, so that the valuable minerals are concentrated and separated from the worthless gangue.
Flowsheet - An illustration showing the sequence of operations, step by step, by which ore is treated in a milling, concentration or smelting process.
Foot wall - The wall or the rock on the underside of a vein or ore deposit.
Forward contract - The sale or purchase of a commodity for delivery at a specified future date.
Fracture - A break in the rock, the opening of which allows mineral-bearing solutions to enter. A "crossfracture" is a minor break extending at more-or-less right angles to the direction of the principal fractures.
Free milling - Ores of gold or silver from which the precious metals can be recovered by concentrating methods without resorting to pressure leaching or other chemical treatment.

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Gabbro - A dark, basic, coarse-grained igneous rock.
Galena - Lead sulphide, the most common ore mineral of lead.
Gangue - The worthless minerals in an ore deposit.
Geochemistry - The study of the chemical properties of rocks.
Geology - The science concerned with the study of the rocks which compose the Earth.
Geophysics - The study of the physical properties of rocks and minerals.
Geophysical survey - A scientific method of prospecting, that measures the physical properties of rock formations. Common properties investigated include magnetism, specific gravity, electrical conductivity and radioactivity.
Geothermal - Pertains to the heat of the Earth's interior.
Glacial drift - Sedimentary material that has been transported by glaciers.
Glacial deposits - A general term for debris transported by glaciers or icebergs, and deposited directly on land or in the sea.
Glaciation - The covering of large land areas by glaciers or ice sheets, including their formation and movement.
- A collective term for the geologic processes of glacial activity, including erosion and deposition, and the resulting effects of such action on the Earth's surface.
- Any of several minor parts of geologic time during which glaciers were more extensive than at present.
Glory hole - An open pit from which ore is extracted, especially where broken ore is passed to underground workings before being hoisted.
Gold equivalent ounces - Often applied to silver ounces produced and sold, converted to a gold equivalent based on a ratio of the average spot market price for the commodities for each year.
Gouge - Fine, putty-like material composed of ground-up rock found along a fault.
Grab sample - A sample from a rock outcrop that is assayed to determine if valuable elements are contained in the rock. A grab sample is not intended to be representative of the deposit, and usually the best-looking material is selected.
Graben - A downfaulted block of rock.
Grade - The amount of valuable mineral in each ton of ore, expressed as troy ounces per ton or grams per tonne for precious metals and as a percentage for other metals.
Granite - A coarse-grained intrusive igneous rock consisting of quartz, feldspar and mica.
Gravity circuit - A method by which mineral particles are separated with the aid of water or air, according to the differences in their specific gravities.
Greenstone belt - An area underlain by metamorphosed volcanic and sedimentary rocks, usually in a continental shield.
Grinding - Size reduction of ore into fine particles to prepare it for processing; comminution.
Grizzly (or mantle) - A grating, usually constructed of steel rails, placed over the top of a chute or ore pass for the purpose of stopping large pieces of rock or ore that may hang up in the pass.
Gross value - The theoretical value of ore determined by applying the assessed grade of metal(s) in the ore by the relevant current market price.
Guides - The timber rails installed along the walls of a shaft for steadying, or guiding, the cage or conveyance.
Gypsum - A sedimentary rock consisting of hydrated calcium sulphate.
Gyratory crusher - A machine that crushes ore between an eccentrically mounted crushing cone and a fixed crushing throat. Typically has a higher capacity than a jaw crusher.

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Hanging wall - The overlying side of an orebody, fault or mine working, especially the wall rock above an inclined vein or fault.
Head grade - The average grade of ore fed into a mill.
Heap leach pad - A large impermeable foundation or pad used as a base for ore during heap leaching.
Heap/ dump leaching - A process used for the recovery of copper, uranium, and precious metals from weathered low-grade ore. The crushed material is laid on a slightly sloping, impervious pad and uniformly leached by the percolation of the leach liquor trickling through the beds by gravity to ponds. The metals are recovered by conventional methods from the solution.
Hectare - One hectare = 2.47 acres.
Hedging - Taking a buy or sell position in a futures market opposite to a position held in the cash market to minimize the risk of financial loss from an adverse price change.
Hematite - An oxide of iron, one of that metal's most common ore minerals.
High grade - Rich ore. As a verb, it refers to selective mining of the best ore in a deposit.
Hoist - The machine used for raising and lowering the cage or other conveyance in a shaft.
Horst - An upfaulted block of rock.
Host rock - The rock surrounding an ore deposit.
Hydrometallurgy - The treatment of ore by wet processes, such as leaching, resulting in the solution of a metal and its subsequent recovery.
Hydrothermal - Of or pertaining to hot water, to the action of hot water, or to the products of this action, such as a mineral deposit precipitated from a hot aqueous solution, with or without demonstrable association with igneous processes; also, said of the solution itself.

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Igneous rocks - Rocks formed by the solidification of molten material from far below the earth's surface.
Impervious - Said of a rock that does not permit the passage of fluids under the pressure conditions ordinarily found in the subsurface.
Induced polarization - A method of ground geophysical surveying, employing an electrical current to determine indications of mineralization.
In situ deposit - Reserves still in the ground.
Indicated Mineral Resource - The part of a Mineral Resource for which quantity, grade or quality, densities, shape and physical characteristics, can be estimated with a level of confidence sufficient to allow the appropriate application of technical and economic parameters, to support mine planning and evaluation of the economic viability of the deposit. The estimate is based on detailed and reliable exploration and testing information gathered through appropriate techniques from locations such as outcrops, trenches, pits, workings and drill holes that are spaced closely enough for geological and grade continuity to be reasonably assumed.
Induced polarisation - A geophysical method developed for ore exploration.
Inferred Mineral Resource - The part of a Mineral Resource for which quantity and grade or quality can be estimated on the basis of geological evidence and limited sampling and reasonably assumed, but not verified, geological and grade continuity. The estimate is based on limited information and sampling gathered through appropriate techniques from locations such as outcrops, trenches, pits, workings and drill holes.
Infill drilling - Diamond drilling at shorter intervals between existing holes, used to provide greater geological detail and to help establish reserve estimates.
Intercept - That portion included between two points in a borehole, as between the point where the hole first encounters a specific rock or mineral body and where the hole enters a different or underlying rock formation.
Intermediate rock - An igneous rock containing 52% to 66% quartz.
Intrusive rock - A body of igneous rock formed by the consolidation of magma intruded into other rocks, in contrast to lavas, which are extruded upon the surface.

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Jaw crusher - A machine in which rock is broken by the action of steel plates.

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Kilometer - 1 kilometer = 0.62 miles.
Kimberlite - A variety of peridotite; the most common host rock of diamonds.

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Lagging - Planks or small timbers placed between steel ribs along the roof of a stope or drift to prevent rocks from falling, rather than to support the main weight of the overlying rocks.
Lamprophyre - An igneous rock, composed of dark minerals, that occurs in dykes; sometimes contains diamonds.
Laterite - A residual soil, usually found in tropical countries, out of which the silica has been leached. May form orebodies of iron, nickel, bauxite and manganese.
Launder - A chute or trough for conveying pulp, water or powdered ore in a mill.
Lava - A general name for the molten rock ejected by volcanoes.
Leachable - Extractable by chemical solvents.
Leaching - The separation, selective removal, or dissolving-out of soluble constituents from a rock or orebody by the natural action of percolating water, or the extraction of soluble metals or salts from an ore by means of slowly percolating solutions; also, a natural process by which ground waters dissolve minerals, thus leaving the rock with a smaller proportion of some of the minerals than it contained originally.
Lens - Generally used to describe a body of ore that is thick in the middle and tapers towards the ends.
Lenticular - A deposit having roughly the form of a double convex lens.
Level - The horizontal openings on a working horizon in a mine; it is customary to work mines from a shaft, establishing levels at regular intervals, generally about 50 metres or more apart.
Life of Mine - Number of years that the operation is planning to mine and treat ore, according to the current mine plan.
Limestone - A bedded, sedimentary deposit consisting chiefly of calcium carbonate.
Line cutting - Straight clearings through the bush to permit sightings for geophysical and other surveys.
Lode - A mineral deposit consisting of a zone of veins, veinlets, disseminations, or planar breccias; a mineral deposit in consolidated rock as opposed to a placer deposit.
Logging - The process of recording geological observations of drill core either on paper or on computer disk.
Long-hole open stope - A method of mining involving the drilling of holes up to 90 feet long into an orebody and then blasting a slice of rock which falls into an open space. The broken rock is extracted and the resulting open chamber is not filled with supporting material.
Longwall - A mining method (common on South African gold mines and European coal mines) involving straight and narrow working faces.

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Mafic - Igneous rocks composed mostly of dark minerals, rich in iron and magnesium.
Magma - The molten material deep in the Earth from which rocks are formed.
Magnetic gradient survey - A geophysical survey using a pair of magnetometers a fixed distance apart, to measure the difference in the magnetic field with height above the ground.
Magnetite - Black, magnetic iron ore, an iron oxide.
Marble - A metamorphic rock derived from the recrystallization of limestone under intense heat and pressure.
Matte - A product of a smelter, containing metal and some sulphur, which must be refined further to obtain pure metal.
Measured Mineral Resource - The part of a Mineral Resource for which quantity, grade or quality, densities, shape, physical characteristics are so well established that they can be estimated with confidence sufficient to allow the appropriate application of technical and economic parameters, to support production planning and evaluation of the economic viability of the deposit. The estimate is based on detailed and reliable exploration, sampling and testing information gathered through appropriate techniques from locations such as outcrops, trenches, pits, workings and drill holes that are spaced closely enough to confirm both geological and grade continuity.
Merrill Crowe circuit - Removal of gold and silver from pregnant cyanide solution by de-oxygenation, followed by precipitation on zinc dust, followed by filtration to recover the resultant auriferous gold and silver slimes.
Metallurgical plant - A processing plant erected to treat ore and extract gold.
Metallurgy - The science of separating metals and metallic minerals from their ores by mechanical and chemical processes; the preparation of more metalliferous materials from raw ore.
Metamorphic rocks - Rocks which have undergone a change in texture or composition as the result of heat and/or pressure.
Metamorphism - The process by which the form or structure of rocks is changed by heat and pressure.
Metre - 1 metre = 3.28 feet.
Mill - A plant where ore is ground fine and undergoes physical or chemical treatment to extract the valuable metals.
Mill head grade - The grade of ore as it comes from a mine and goes to a mill.
Milling circuit - The combination of various processes and systems which concentrate the valuable minerals.
Mine - An excavation beneath the surface of the ground from which mineral matter of value is extracted.
Mineral deposit - A mineralized body which has been delineated by appropriately spaced drilling and/or underground sampling to support a sufficient tonnage and average grade of metal. This material or deposit does not qualify as a reserve until a comprehensive evaluation, based on costs, grade, recoveries and other factors, demonstrates economic feasibility. Consequently, although the potential exists, there is no assurance that this mineral deposit will ever become an ore reserve.
Mineral extraction - Crushing and separating ore into valuable substances or waste by any of a variety of techniques.
Mineral resource - A concentration or occurrence of material of economic interest in or on the earth's crust in such form, quality and quantity that there are reasonable and realistic prospects for eventual economic extraction. The location, quantity, grade, continuity and other geological characteristics of a mineral resource are known, estimated from specific geological evidence and knowledge, or interpreted from a well-constrained and portrayed geological model. Mineral resources are subdivided, in order of increasing geological confidence, into inferred, indicated and measured categories. The mineral resources are inclusive of those resources which have been modified to produce ore reserves.
Mineralization - The process or processes by which mineral or minerals are introduced into a rock, resulting in a valuable or potentially valuable deposit.
Mineralized material - The projection of mineralization in rock based on geological evidence and assumed continuity. It may or may not be supported by sampling, but is supported by geological, geochemical, geophysical or other data. This material may or may not have economically recoverable mineralization.
Mining claim - That portion of public mineral lands which a party has staked or marked out in accordance with federal, provincial or state mining laws to acquire the right to explore for and exploit the minerals under the surface.
Mining dilution - Rock blocks that are, by necessity, removed along with the ore in the mining process, subsequently lowering the grade of the ore.
Muck - Ore or rock that has been broken by blasting.
Muck sample - A representative piece of ore that is taken from a muck pile and then assayed to determine the grade of the pile.

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National Instrument 43-101 - Canadian rule that governs how issuers disclose scientific and technical information about their mineral projects to the public.
Native metal - A metal occurring in nature in pure form, uncombined with other elements.
Net profit interest - A proportion paid out to a particular investor from the profit remaining after all charges, including taxes and bookkeeping charges such as depreciation, have been deducted.
Net smelter return - A royalty based on a percentage of gold produced with settlement made either in kind or in currency, based on the spot gold sale proceeds received less the cost of refining at an off-site refinery.
Noble metal - A metal or alloy, such as gold, that is highly resistant to oxidation and corrosion.
Nugget - A small mass of precious metal, found free in nature.

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Open pit - A mine that is entirely on the surface. Also referred to as open-cut or an open-cast mine (the latter normally for coal and industrial mineral operations).
Ore - Rock, generally containing metallic or non-metallic minerals that can be mined and processed at a profit. Also, the mineral(s) thus extracted.
Ore shoot - An elongated pipelike, ribbonlike, or chimneylike mass of ore within a deposit (usually a vein), representing the more valuable part of the deposit.
Ore slurry - The fine carbonaceous discharge from a mine washery. All washeries produce some slurry, which must be treated to separate the solids from the water in order to have a clear effluent for reuse or discharge.
Orogeny - A period of mountain-building characterized by the folding of a portion of the earth's crust.
Orebody - A sufficiently large amount of ore that can be mined economically.
Ounce (troy) - Used in imperial statistics, a troy ounce is equal to 31.1035 grams.
Outcrop - An exposure of rock or mineral deposit that can be seen on surface, that is not covered by soil or water.
Overburden - Barren rock material, either loose or consolidated overlying a mineral deposit, which must be removed prior to mining.
Oxide ore - Mineralized rock in which some of the original minerals have been oxidized. Oxidation tends to make the ore more porous and permits a more complete permeation of cyanide solutions so that minute particles of gold in the interior of the minerals will be readily dissolved.
Oxide ore - Mineralized rock in which some of the original minerals have been oxidized. Oxidation tends to make the ore more porous and permits a more complete permeation of cyanide solutions so that minute particles of gold in the interior of the minerals will be readily dissolved
Oxidized zone - An area of mineral deposits modified by surface waters, e.g. sulfides altered to oxides and carbonates.

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Pan - To wash gravel, sand or crushed rock samples in order to isolate gold or other valuable metals by their higher density.
Participating interest - A company's interest in a mine, which entitles it to a certain percentage of profits in return for putting up an equal percentage of the capital cost of the project.
Paste-fill - Back-filling of mined-out underground areas with finely ground rock in a slurry.
Patenting - A process established under the U.S. General Mining Law of 1872 which permits the conversion of mining claims on federal lands into full fee ownership, provided certain conditions are met.
Peridotite - An intrusive igneous rock consisting mainly of olivine.
Permeable - Pertaining to a rock or soil having a texture that permits passage of liquids or gases under the pressure ordinarily found in earth materials.
Pillar - A block of solid ore or other rock left in place to structurally support the shaft, walls or roof of a mine.
Placer - A deposit of sand and gravel containing valuable metals such as gold, tin or diamonds.
Plunge - The vertical angle a linear geological feature makes with the horizontal plane.
Porphyry - Any igneous rock in which relatively large crystals , called phenocrysts, are set in a fine-grained groundmass.
PPM - Parts per million, also gram/tonne
PPB - Parts per billion.
Pregnant pond - Pond containing solution which has percolated through the ore on a heap leach. The solution is impregnated with gold and silver removed from the ore.
Primary deposits - Valuable minerals deposited during the original period of mineralisation, as opposed to those deposited as a result of alteration or weathering.
Probable ore - Material for which tonnage and grade are computed partly from specific measurements, samples or production data and partly from projection for a reasonable distance on geological evidence; and for which the sites available for inspection, measurement and sampling are too widely or otherwise inappropriately spaced to outline the material completely or to establish its grade throughout.
Prospect - A mining property, the value of which has not been determined by exploration.
Proven ore - Material for which tonnage and grade are computed from dimensions revealed in outcrops, trenches, underground workings or drill holes; grade is computed from the results of adequate sampling; and the sites for inspection, sampling and measurement are so spaced and the geological character so well-defined that size, shape and mineral content are established.
Pulp - Pulverized or ground ore in solution.
Pyrite - A common, pale-bronze or brass-yellow, isometric mineral. It is dimorphous with marcasite and often contains small amounts of other metals. Pyrite has a brilliant metallic luster and an absence of cleavage, and has been mistaken for gold. Pyrite is the most wide-spread and abundant of the sulfide minerals and occurs in all kinds of rocks, such as in nodules in sedimentary rocks and coal seams or as a common vein material associated with many different minerals.

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Quartz - Crystalline silica, an important rock-forming mineral. It is, next to feldspar, the commonest mineral, occurring either in transparent hexagonal crystals (colorless, or colored by impurities) or in crystalline or cryptocrystalline masses. Quartz is the commonest gangue mineral of ore deposits, forms the major proportion of most sands and has a widespread distribution in igneous, metamorphic and sedimentary rocks.
- general term for a variety of non-crystalline or cryptocrystalline minerals having the same chemical composition as that of quartz, such as chalcedony, agate, and opal.
Quartzite - A granoblastic metamorphic rock consisting mainly of quartz and formed by recrystallization of sandstone or chert by either regional or thermal metamorphism.
- A very hard but un-metamorphosed sandstone, consisting chiefly of quartz grains that have been so completely and solidly cemented with secondary silica that the rock braks across or through the grains rather than around them. The cement grows in optical and crystallographic continuity around each quartz grain, thereby tightly interlocking the grains as the original pore spaces are filled.

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Raise - A vertical hole between mine levels used to move ore or waste rock or to provide ventilation.
Ramp - An inclined underground tunnel which provides access for exploration or a connection between levels of a mine.
Reclamation - The process by which lands disturbed as a result of mining activity are reclaimed back to a beneficial land use. Reclamation activity includes the removal of buildings, equipment, machinery and other physical remnants of mining, closure of tailings impoundments, leach pads and other mine features, and contouring, covering and re-vegetation of waste rock piles and other disturbed areas.
Recovered grade - Actual metal content of ore determined after processing.
Recovery rate - A term used in process metallurgy to indicate the proportion of valuable material obtained in the processing of an ore. It is generally stated as a percentage of the material recovered compared to the total material present in the ore.
Reef - A gold-bearing sedimentary horizon, normally a conglomerate ban, that may contain economic levels of gold.
Refining - The final stage of metal production in which impurities are removed from the molten metal.
Refractory material - Gold mineralized material in which the gold is not amenable to recover by conventional cyanide methods without any pretreatment. The refractory nature can be either silica or sulphide encapsulation of the gold or the presence of naturally occurring carbons which reduce gold recovery. Material of this nature is difficult or expensive to recover its valuable constituents.
Rehabilitation - The process of reclaiming land disturbed by mining to allow an appropriate post-mining use and address among other issues, ground and surface water, topsoil, final slope gradient, waste handling and re-vegetation issues.
Reserve - The quantity of mineral that is calculated to lie within given boundaries. It is described as total (or gross), workable, or probable working, depending on the application of certain arbitrary limits in respect of deposit thickness, depth, quality, geological conditions, and contemporary economic factors. Proved, probable, and possible reserves are other terms used in general mining practice.
Resource - A Mineral Resource is a concentration or occurrence of natural, solid, inorganic or fossilized organic material in or on the Earth's crust in such form and quantity and of such a grade or quality that it has reasonable prospects for economic extraction. The location, quantity, grade, geological characteristics and continuity of a Mineral Resource are known, estimated or interpreted from specific geological evidence and knowledge.
Reverse circulation drilling - Drilling that produces rock chips rather than core. Faster and cheaper than diamond drilling, the chips are forced by air to surface for examination.
Reverse circulation holes - Holes drilled using a process where the circulation of bit-coolant and cuttings removal liquids, drilling fluid, mud or air down the borehole outside the drill rods and upward inside the drill rods. Also called countercurrent; counter flush.
Rhyolite - A fine-grained, extrusive igneous rock which has the same chemical composition as granite.
Rock factor - The number of cubic metres of a particular rock type required to make up one tonne of the material. One tonne of a highly siliceous ore may occupy 0.40 cubic metres, while a tonne of dense sulphide ore may occupy only 0.25 cubic metres.
Rock mechanics - The study of the mechanical properties of rocks, which includes stress conditions around mine openings and the ability of rocks and underground structures to withstand these stresses.
Room-and-pillar mining - A method of mining flat-lying ore deposits in which the mined-out area, or rooms, are separated by pillars of approximately the same size.
Rod & tube mills - These are types of circular grinding mills used to break the ore down into fine particles in preparation for dissolving out the gold by means of cyanide.
Run-of-mine - A term used loosely to describe ore of average grade.

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SAG mill - Semi-autogenous grinding mill, grinding rock into fine powder whereby the grinding media consists of larger chunks of rocks and steel balls.
Sample - A small portion of rock or a mineral deposit taken so that the metal content can be determined by assaying.
Sampling - Selecting a fractional but representative part of a mineral deposit for analysis.
Sandstone - A sedimentary rock consisting of grains of sand cemented together.
Secondary enrichment - Enrichment of a vein or mineral deposit by minerals that have been taken into solution from one part of the vein or adjacent rocks and redeposited in another.
Sediment - Solid fragmental material that originates from weathering of rocks and is transported or deposited by air, water, or ice, or that accumulates by other natural agents, such as chemical precipitation from solution or secretion by organisms, and that forms in layers on the Earth's surface at ordinary temperatures in a loose, unconsolidated form; e.g., sand, gravel, silt, mud, alluvium.
Sedimentary rock - Rocks formed from material derived generally by erosion of other rocks and laid down by a chemical or mechanical process i.e., limestone, shale and sandstone.
Shaft - A vertical passageway to an underground mine for moving personnel, equipment, supplies and material including ore and waste rock.
Sheeted veins - A group of closely spaced, distinct parallel fractures filled with mineral matter and separated by layers of barren rock.
Shotcrete - A mixture made of course aggregate, applied by pneumatic pressure through a specially adapted hose and used as a fireproofing agent and as a sealing agent to prevent weathering of mine timbers and roadways.
Shoot - A concentration of mineral values; that part of a vein or zone carrying values of ore grade.
Siliceous - A rock containing an abundance of quartz.
Slurry - A mixture of crushed and finely ground solids with water.
Smelting - A metallurgical operation in which metal is separated from impurities by a process that includes fusion.
Spot bolting - The use of one or just a few roof bolts at spot locations.
Station - An enlargement of a shaft made for the storage and handling of equipment and for driving drifts at that elevation.
Stockpile - Broken ore heaped on surface or prepared areas underground, pending treatment or shipment.
Stockwork - A mineral deposit consisting of a 3-dimensional network of planar to irregular veinlets spaced closely enough that the whole mass can be mined.
Stope - An area in an underground mine where ore is mined (usually in a longwall).
Stoping - The process of mining the orebody on the plane of the reef.
Stoping width - The sum of the channel width and external waste widths.
Stratigraphy - Strictly, the description of bedded rock sequences; used loosely, the sequence of bedded rocks in a particular area.
Stratum/ strata - A bed or layer of rock; strata, more than one layer.
Strike fault - A fault whose strike is parallel to the strike of the strata.
Strike length - The longest horizontal dimension along which drilling results have established mineralization.
Stripping Ratio - The ratio of the number of tonnes of waste material removed to the number of tonnes of ore removed, used in connection with open pit mining.
Sulphide ore - A sub-group of refractory ore - mineralized rock in which much of the gold is encapsulated in sulphides and is not readily amenable to dissolution by cyanide solutions - associated with sulphide minerals (primarily pyrite) that have not been oxidized. Some sulphide ore may require autoclaving or roasting prior to cyanidation.
Sustainable development - Industrial development that does not detract from the potential of the natural environment to provide benefits to future generations.
SX/EW - Solvent extraction, electrowinning.
Syenite - An intrusive igneous rock composed chiefly of orthoclase.
Syncline - A down-arching fold in bedded rocks.
Syngenetic - A term used to describe when mineralization in a deposit was formed relative to the host rocks in which it is found. In this case, the mineralization was formed at the same time as the host rocks. (The opposite is epigenetic.)

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Tailings - Material rejected from a mill after most of the recoverable valuable minerals have been extracted.
Tailings dam - A natural or man-made area suitable for depositing the material that remains after the treatment of ore.
Thermal regeneration - The process of heating activated carbon granules typically to 750 degrees Celsius to restore carbon properties for the next gold extraction cycle.
Thickener - A vessel or apparatus for reducing the proportion of water in a pulp by means of sedimentation.
Thrusting event - A period of structural compression in geological time with the generation of low-angle thrust faults.
Ton - Used in imperial statistics. Equal to 2,000 pounds. Referred to as a short ton.
Tonnage - Quantities where the ton or tonne is an appropriate unit of measure. Typically used to measure resources and reserves of gold-bearing material in situ or quantities of ore and waste material mined, transported or milled.
Tonne - Used in metric statistics. 1 tonne= 2,205 pounds.
Total cash cost - Production costs calculated in accordance with the Gold Institute Standard, including direct mining expenses, mine development adjustments, refining and transportation costs, by-product credits, royalties and production taxes.
Total production cost - Production costs comprised of total cash production cost plus depreciation, depletion and reclamation provisions.
Tram - To haul cars of ore or waste in a mine.
Trench - A long, narrow excavation dug through overburden or blasted out of rock, to expose a vein or ore structure.
Trend - The direction, in the horizontal plane, of a linear geological feature, such as an ore zone.
Troy ounce - Used in imperial statistics. 1 troy ounce= 31.10348 grams.
Tube mill - An apparatus consisting of a revolving cylinder about half-filled with steel rods or balls and into which crushed ore is fed for fine grinding.
Tunnel - A horizontal underground opening, open to the atmosphere at both ends.

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Uncut value - The actual assay value of a core sample as opposed to a cut value, which has been reduced by some formula.
UTEM - Deep electromagnetic survey.

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Vein - A fissure, fault or crack in a rock filled by minerals that have travelled upwards from some deep source.
Visible gold - Native gold which is discernible, in a hand specimen, to the unaided eye.
Volcanic rocks - Igneous rocks formed from magma that has flowed out or has been violently ejected from a volcano.
Volcanogenic - A term used to describe the volcanic origin of mineralization.

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Warrant - A derivative security that gives the holder the right to purchase securities (usually equity) from the issuer at a specific price within a certain time frame. Warrants are often included in a new debt issue to entice investors.
Waste - Material that contains insufficient mineralization for consideration for future treatment and, as such, is discarded.
Witness post - A claim post placed on a claim line when it cannot be placed in the corner of a claim because of water or difficult terrain.
Winze - An internal shaft.
Writeoffs - Amounts deducted from a company's reported profit for depreciation or preproduction costs. Writeoffs are not an out-of-pocket expense, but reduce the amount of taxable profit.

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Zinc precipitation - The chemical reaction using zinc dust that converts gold solution to a solid form for smelting into unrefined gold bars.
Zone - An area of distinct mineralization.

   

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