| a combustible mixture of gaseous hydrocarbons that accumulates in porous sedimentary rocks, esp. those yielding petroleum, consisting usually of over 80 percent methane together with minor amounts of ethane, propane, butane, nitrogen, and, sometimes, helium: used as a fuel and to make carbon black, acetylene, and synthesis gas. |
natural gas  (nāch'ər-əl) Pronunciation Key
A mixture of hydrocarbon gases that occurs naturally beneath the Earth's surface, often with or near petroleum deposits. Natural gas contains mostly of methane but also has varying amounts of ethane, propane, butane, and nitrogen. It is used as a fuel and in making organic compounds. |