Prop - Coal mining term for any single post used as roof support. Not precise, but very useful for determining the commercial value. Sulfur and Btu content are also generally reported with a proximate analysis. Pyrite - A hard, heavy, shiny, yellow mineral, FeS2 or iron disulfide, generally in cubic crystals. Also called iron pyrites, fool's gold, sulfur balls.
Iron pyrite is the most common sulfide found in coal mines.
Ramp - A secondary or tertiary inclined opening, driven to connect levels, usually driven in a downward direction, and used for haulage. The classification of coal by degree of hardness, moisture and heat content. It is the most common coal found in the United States and is used to generate electricity and to make coke for the steel industry. It has low fixed carbon and high percentages of volatile matter and moisture. It is used for generating electricity and for conversion into synthetic gas.