The international unit for measuring magnetic flux density.

Native gold: 

Metallic gold in its free or uncombined state. Placer gold.

Native metal: 

A metal occurring in nature in pure form, uncombined with other elements.

Natural riffles: 

Small steps or ledges in bedrock. Depressions holding gold.

Net smelter return: 

An interest in a mining property held by the vendor on the net revenue generated from the sale of metal produced by the mine.


A rounded lump or mass of mineral.

Noncash costs: 

Costs that are typically accounted for ratably over the life of an operation (which include depreciation and amortization of capital assets, accruals for the costs of mine reclamation and amortization of property acquisition costs).


Containing little or no metal; industrial mineral.


A coarse-grained igneous rock that is host to copper/nickel deposits in the Sudbury area of Ontario. (see Gabbro)


A small mass of precious metal, found free in nature.


Existence or how a mineral is deposited.

Ocean crust: 

The relatively thin, solid portion of the Earth's surface underlying the oceans.


A polyhedron with eight plane surfaces.

Open pit: 

A surface mine, open to daylight, such as a quarry. Also referred to as open-cut or open-cast mine.

Operating cost: 

Cash cost plus depreciation and amortization.


An agreement to purchase a property reached between the property vendor and some other party that wishes to explore the property further.


A mixture of ore minerals and gangue from which at least one of the metals can be extracted at a profit.


A mineral deposit with sufficient tonnage and grade from which a commodity may be mined, processed and sold economically.

Ore pass: 

Vertical or inclined passage for the downward transfer of ore connecting a level with the hoisting shaft or a lower level.

Ore Reserves: 

Ore reserves: a proven and probable reserve is that part of a mineral deposit which could be extracted or produced economically and legally at the time of the reserve determination.


The portion, or length, of the vein, or other ore structure, that carries sufficient valuable mineral to be extracted profitably.


Of plant or animal origin.

Organic maturation: 

The process of turning peat into coal.


The process of mountain-building by folding and faulting of the Earth's crust.


Troy ounces of a fineness of 999.9 parts per 1,000 parts, equal to 31.1034 grams.


An exposure of rock or mineral deposit that can be seen on surface, i.e., that is not covered by overburden or water.


Surface waste materials covering a mineral deposit.


Sedimentary beds that have been deformed in such a way that the oldest beds are lying on top of younger beds.


A chemical reaction caused by exposure to oxygen that results in a change in the chemical composition of a mineral.


Any chemical combination with oxygen.


To combine with oxygen.

Oxidized ore: 

The alteration of metalliferous minerals by weathering and the action of surface waters and their conversion, partly or wholly into oxides, carbonates or sulfates.

Oxidized zone: 

Portion of ore deposit where oxygen has displaced other non-metallic elements in chemical combination with metals.


To wash (in a metal, bowl-like pan) gravel and sand or rock samples that have been ground to small particles, in order to separate gold or other valuable metals.

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.


Fire assay procedure for separating gold from other metals.


The ultimate stage of holding a mineral claim, after which no more assessment work is necessary; determines that all mineral rights, both surface and underground have been earned.


A process established under the General Mining law of 1872 which permits the conversion of mining claims on federal lands into full fee ownership, provided certain conditions are met.

Pay streak: 

A layer or channel within a gravel deposit that contains a much higher average gold content that the surrounding gravels.


A coarse-grained, igneous rock, usually irregular in texture and composition, similar to a granite in composition; it usually occurs in dykes or veins and sometimes contains valuable minerals.


A marble-sized ball of iron ore bonded by clay and fused for hardness.


A yellowish-brown iron and nickel sulfide mineral.


An intrusive igneous rock consisting mainly of olivine.


A term used to describe the coarse grained texture of some igneous rocks.


A porphyritic crystal inclusion.


Scaly minerals, micas, chlorites and clays; a term more recently applied to minerals with a layered crystal structure.

Picket line: 

A reference line, marked by pickets or stakes, established on a property for mapping and survey purposes.


Common term for an ingot of cast metal.

Pig iron: 

Crude cast iron from a blast furnace.


A block of solid ore or rock left in place to structurally support the shaft, walls or roof in a mine.

Piss ditch: 

A ditch which runs along one side of a mine tunnel to provide drainage of seepage water while keeping the center of the tunnel reasonably dry for walking or wheelbarrowing.


Refers to the relative angle of slope or dip of an ore deposit.


An important uranium ore mineral, containing a high percentage of uranium oxide. It is black in color, possesses a characteristic pitch like or greasy luster and is highly radioactive.


Digging test pits for sampling gravels.


An alluvial deposit of sand and gravel containing valuable metals such as gold, tin, etc.

Placer mining: 

Mining sand and gravel deposits for their mineral content.


A building or group of buildings, and their contained equipment, in which a process or function is carried out; on a mine it will include warehouses, hoisting equipment, compressors, maintenance shops, offices, mill or concentrator.

Plate tectonics: 

A geological theory which postulates that the Earth's crust is made up of a number of rigid plates which collide, rub up against and spread out from one another.


A metal of white color like silver, but of inferior luster. It is the heaviest of known metals.


A common name for a small offshoot from a larger batholith.


The vertical angle an orebody makes between the horizontal plane and the direction along which it extends, longitudinally to depth.


Refers to rocks of igneous origin that have come from great depth.


A small area where large quantity’s of valuable metals are concentrated.

Polishing pond: 

The last in a series of settling ponds through which mill effluent flows before being discharged into the natural environment.


The relative quantity of holes or opening in a substance.


Any igneous rock in which relatively large, conspicuous crystals (called phenocrysts) are set in a fine-grained or aphanitic groundmass.

Porphyry copper: 

A deposit of disseminated copper minerals in a large body of porphyry.


The surface entrance to a tunnel or adit.


A list of financial assets.

Positive ore: 

See Ore Reserves.

Possible ore: 

See Ore Reserves.

Possible reserves: 

Valuable mineralization not sampled enough to accurately estimate its tonnage and grade, or even verify its existence. Also called "inferred reserves".


A vertical but slightly slanted timber which supports the header and lagging in underground sets.


Potassium compounds mined for fertilizer and for use in the chemical industry.

Precambrian Shield: 

An area covering much of northern Canada consisting of the oldest, most stable part of the North American continental plate.


The material that settles from a liquid solution as a result of a chemical reaction when a particular substance is added to the solute.

Pregnant pond: 

A pond containing solution which has been percolated through the ore on the pad. The solution is impregnated with gold and silver removed from the ore.


Removal of overburden in advance of beginning operations to remove ore in an open pit operation.


The original or unaltered form.

Primary deposits: 

Ore minerals deposited during the original period or periods of metallization as opposed to those deposited as a result of alteration or weathering.

Probable ore: 

See Ore Reserves.

Probable reserves: 

Valuable mineralization not sampled enough to accurately estimate the terms of tonnage and grade. Also called "indicated reserves".

Profile, Soil: 

The term given to layers of soils, gravel, rock, etc. which occur down a vertical 'face'. The layering is usually indicative of alluvial activity: soils and rocks being transported into a site in succeeding geologic eras.

Pro rata: 

In proportion (to ownership, income or contribution).


A mining property, the value of which has not been proven by exploration.


The search for valuable mineral deposits.


The younger of two Precambrian systems or eras.

Proton precession magnetometer: 

A geophysical instrument which measures magnetic field intensity in terms of vertical gradient and total field.

Proven reserves: 

Reserves that have been sampled extensively by closely spaced diamond drill holes and developed by underground workings in sufficient detail to render an accurate estimation of grade and tonnage. Also called "measured reserves".


Pulverized or ground ore in solution.


A common sulfide mineral, shiny and yellow in color and composed of sulfur and iron, sometimes known as "fool's gold".

Pyroclastic deposits: 

Deposits made up of rock material expelled aerially from a volcanic vent.


An iron sulfide, less common than pyrite, bronze in color and magnetic; some times is associated with nickel, in which case it may be mined as a nickel ore.