Petroleum: black, dark brown or greenish liquid found in porous rock formations in the earth. The American Petroleum Institute, in its Manual of Petroleum Measurement Standards (MPMS), defines it as "a substance, generally liquid, occurring naturally in the earth and composed mainly of mixtures of chemical compounds of carbon and hydrogen with or without other nonmetallic elements such as sulfur, oxygen, and nitrogen." (1)
Also known as:
Crude Oil
Bitumen
Petrol
Vaseline (brand name)
References
1. Petroleum
