Needle. An instrument used in blasting coal, with which a channel is formed through the tamping for the entrance of the squib.
Nut coal. One of the regular sizes of bituminous coal.
Opening. Any excavation in or into a mine.
Operator. The person, firm, or corporation working a colliery.
Outcrop. That portion of any geological stratum which appears at the surface.
Output. The amount of coal produced from any mine, or from any area of country.
Parting. The layer of slate or bony coal which separates two benches of a coal seam.
Pea coal. One of the regular sizes of prepared anthracite.
Picking shute. A shute in the breaker from which the pieces of slate are picked out by a boy as they pass down with the coal.
Pillar. A column or body of coal left unmined to support the roof.