Coke is a fuel with few impurities and a high
carbon content, usually made from
coal. It is the solid
carbonaceous material derived from
destructive distillation of low-ash, low-sulfur
bituminous coal. Cokes made from coal are grey, hard, and
porous. While coke can be formed naturally, the commonly used form is man-made. The form known as
petroleum coke, or pet coke, is derived from oil refinery coker units or other cracking processes.