A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

O

Occurrence       Existence or how a mineral is deposited.

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

Odd lot       A block of shares that is less than a board lot.

Open end pillaring       A method of mining pillars in which no stump is left; the pockets driven are open on the gob side and the roof is supported by timber.

Open order       An order to buy or sell stock, which is good until cancelled by the client.

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

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

Option (on stock)       The right to buy (or sell) a share at a set price, regardless of market value.

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

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       The calculated tonnage and grade of mineralization which can be extracted profitably; classified according to the level of confidence that can be placed in the data.

Ore Zone (Orebody)       A continuous, well-defined mass of material of sufficient ore content to make extraction economically feasible.

Orebody       A natural concentration of valuable material that can be extracted and sold at a profit.

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

Organic       Of plant or animal origin.

Organic maturation       The process of turning peat into coal.

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

Outby; outbye       Nearer to the shaft, and hence farther from the working face. Toward the mine entrance. The opposite of inby.

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

Overburden       Layers of soil and rock covering a coal seam. Overburden is removed prior to surface mining and replaced after the coal is taken from the seam.