A naturally occurring fuel gas consisting of mostly methane but which has some ethane, butane, propane and nitrogen. It is colorless, and almost odorless unless a warning odor has been added, and has an ignition temperature of 900-10000F, and an explosive range of (3)8 to 17 percent. It is used for fuel and cooking, for the synthesis of ammonia and as a raw material for the petrochemical industry; as a liquid it is called liquefied natural gas (LNG).