Gas Abundance

the amount of gas liberated per unit of mass or volume of a mineral during its extraction. Gas abundance depends on the gas-bearing capacity, as well as on the gas permeability, the method and intensity of extraction of the mineral, the depth of the mining, and the pressure of the gas enclosed in the joints and pores of the mineral and the surrounding rock. During underground mineral extraction, the quantity of gas escaping into the underground mining area per unit of time is called the absolute gas abundance; the relative gas abundance refers to a unit of mineral extracted per unit of time (usually per day). The gas abundance of mines refers to the amount of gas that escapes from seams of coal (ore) and rock. Mines (pits) that give off methane are called gas mines. Mines in the USSR are classified in four categories according to the amount of escaping methane, hydrogen, or other explosive gas per ton of daily mineral (coal or ore) extraction.