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

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Lacustrine deposit       Sediments deposited on the bottom of lakes.

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. Secondary timber placed behind main timber in a shaft, drive, tunnel or adit to support loose rock.

Lamp       The electric cap lamp worn for visibility. Also, the flame safety lamp used in coal mines to detect methane gas concentrations and oxygen deficiency.

Lamprophyre       An igneous rock, composed of dark minerals, that occurs in the form of dykes.

Laterite       A residual soil developed 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.

Lay       The general direction or slope of a device or ground surface.

Layout       The design or pattern of the main roadways and workings. The proper layout of mine workings is the responsibility of the manager aided by the planning department.

Leachable       Extractable by chemical solvents.

Leaching       A chemical process for the extraction of valuable minerals from ore; 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.

Lead       The bottom portion of gold-bearing channel gravels, particularly in buried placers.

Ledge       A horizontal layer of rock.

Leg Wires       The wires attached to an electric blasting cap used for initiating its detonation.

Lens       Generally used to describe a body of ore that is thick in the middle and tapers towards the ends.

Lenticular       A lens-shaped deposit having roughly the form of a double convex lens.

Lessee       The person leasing or optioning a mining property.

Level       A horizontal tunnel or drift in an underground mine.

Levet       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 m or more apart.

Lift       The amount of coal obtained from a continuous miner in one mining cycle.