A

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 (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.
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.