Anthracite

Anthracite (Greek aνθρακίτης (anthrakítes), "coal-like," from άνθραξ (ánthrax), coal) is a hard, compact variety of mineral coal that has a high luster. It has the highest carbon content, the fewest impurities, and the highest calorific content of all types of coals, which also include bituminous coal and lignite.