is a standard for measuring energy. A Btu is the amount of energy required to raise the temperature of one pound of water one degree Fahrenheit.

is a hard, dry substance used in the manufacture of iron and steel. It is produced by heating coal to a very high temperature without the presence of air.

is an underground mining machine that removes coal from the face and loads it onto conveyors.

is a method that includes using explosives in a coal seam, fracturing the seam and removing the coal onto a conveyor or shuttle car.

, a large, electrically-powered excavating machine used in the surface mining process to remove heavy rock and soils above the coal seam.

is commonly used to describe the exposed area of a coal seam from which coal is extracted.

is a term representing coal, crude oil or natural gas that is formed from the fossil remains of organic material.

is a process by which coal is converted into low, medium or high-Btu gas.

is the unexcavated face of exposed overburden and coal at a surface mine.

is a unit of electricity measurement. One kilowatt hour equals 1,000 watts of electricity used for one hour.