Due largely to its potential for explosions -- making hash oil via butane extraction is presently illegal in California.
Hash oil, not to be confused with hempseed oil, is used for both medicinal and recreational purposes and made from the mature female flowers and leaves of the herb cannabis, thus having a much higher THC content.
oil | Standard Oil | Gulf Oil | Deepwater Horizon oil spill | Shell Oil Company | Midnight Oil | 1973 oil crisis | oil refinery | oil painting | Oil platform | Castor oil plant | Oil Campaign of World War II | Hash function | Secure Hash Algorithm | oil platform | North Sea oil | Anglo-Persian Oil Company | Prestige oil spill | Oil-for-Food Programme | Oil | Indian Oil Corporation | vegetable oil | Nippon Oil | Vacuum Oil Company | South Cuyama Oil Field | Russell Ranch Oil Field | Oil well | oil well | National Iranian Oil Company | Lucas Oil Stadium |