Oleum was an unincorporated community in Contra Costa County, California, United States., located between the City of Hercules and the unincorporated town of Rodeo. It was a small company town, with housing for Union Oil company workers, hence the name, derived from "petroleum". The refinery still exists.
The site is located on the Mexican land grant Rancho El Pinole made to Ygnacio Martinez. A post office operated at Oleum from 1910 to 1951.
- ^ a b c d e "Oleum (Contra Costa County, California)". Geographic Names Information System. United States Geological Survey. Retrieved May 11, 2014.
- ^ a b "FIPS55 Data: California". FIPS55 Data. United States Geological Survey. February 23, 2006. Retrieved May 11, 2014.