Xylene (from Greek ξύλο, xylo, "wood"), xylol or dimethylbenzene is an aromatic hydrocarbon mixture consisting of a benzene ring with two methyl groups at various substituted positions. The three isomers of xylene have the molecular formula C8H10, also represented by the semi-structural formula C6H4(CH3)2. Xylene is a major petrochemical produced by catalytic reforming and also by coal carbonisation in the manufacture of coke fuel.