Bitumen is also sometimes confused with petroleum pitch which, although also derived from crude oil, is a substance produced by a different process from that used for refined bitumen. Petroleum pitches are the residues from the extreme heat treatment or “cracking” of petroleum fractions. Their properties and chemical composition are therefore quite different from those of bitumen.
Naturally-occurring bitumen, sometimes also called natural asphalt, rock asphalt, lake asphalt or oil sand, has been used as an adhesive, sealant and waterproofing agent for over 8,000 years. But it occurs only in small quantities and its properties are quite different from refined bitumen.