Coal is a brown-black sedimentary rock which is combustible. It is a fossil fuel and is formed from fossilised biological matter (e.g. peat). Its main use is in the production of energy (coal power stations). It can be used as a fuel for a solid fuel hearth. It is also the raw material from which coke is made, a fuel which is also used in solid fuel forges as well as being the fuel of choice in steel production.