Mineral coal is a combustible sedimentary rock, black or brown in colour, which occurs in strata called layers of coal. Harder forms, such as anthracite, can be considered metamorphic rocks due to subsequent exposure to elevated temperature and pressure. It consists basically of carbon, sulphur, hydrogen, oxygen and nitrogen, as well as trace elements. The higher the carbon content, the purer it is considered. There are four main types of coal: peat, lignite, coal and anthracite (in increasing order of carbon content). It is extracted from the ground by open or underground mining.

Among the various fuels produced and conserved by nature in the fossilized form, it is believed to be the most abundant mineral coal. With coke and coal tar, its by-products are vital to many modern industries.