a. In coal mining, bodies of combustible gases that tend to collect in
higher parts of mine workings and at the edge of goaves and wastes. They
are found in cavities, at ripping lips, at other sheltered places
protected from the ventilating current, and at the higher sides of rise
b. The concentration or gathering of oil or gas in some form of trap.
Commercial accumulation is a volume or quantity sufficient for profitable
Dictionary of Mining, Mineral, and Related Terms