Glossary of Mining Terms

    • 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.
    • Adit -An opening driven horizontally into the side of a mountain or hill for providing access to a mineral deposit.
    • 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 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 -Relatively recent deposits of sedimentary material 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.
    • 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.
    • 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 -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.
    • 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 (meter, inch, centimeter) – The assay value multiplied by the number of feet, meters, inches, centimeters 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.
    • 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.
    • 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.