Carbon the very large masses of carbonate rock (limestone, dolomite, marble and so on). Coal is very rich in carbon (anthracite contains 92–98%) and is the largest commercial source of mineral carbon, accounting for 4,000 gigatonnes or 80% of fossil fuel. As for individual carbon allotropes, graphite is found in large quantities in the United States (mostly in New York and Texas), Russia, Mexico, Greenland, and India. Natural diamonds occur in the rock kimberlite, found in ancient volcanic "necks", or "pipes". Most diamond deposits are in Africa, notably in South Africa, Namibia, Botswana, the Republic of the Congo, and Sierra Leone.
Metallurgical coal Metallurgical coal Metallurgical coal is a grade of low-ash, low-sulfur and low-phosphorus coal that can be used to produce high grade coke. Coke is an essential fuel and reactant in the blast furnace process for primary steelmaking. The demand for metallurgical coal is highly coupled to the demand for steel. Primary steelmaking companies will often have a division that produces coal for coking, to ensure stable and low-cost supply. Metallurgical coal is distinguished by the strong low-density coke produced when the coal is heated in a low-oxygen environment to reduce mineral impurities (e.g. less sulfur, phosphorus). On heating, the coal