Because of its extreme reactivity, fluorine does not occur uncombined in nature. Fluorine gas is produced commercially by electrolysis of a solution of hydrogen fluoride containing potassium hydrogen fluoride. Cryolite and apatite are other important natural compounds. Although there was no commercial production of fluorine before World War II, the use of the gas in a process for refining uranium ores prompted its manufacture. The importance of fluorine lies largely in its compounds.
Sodium fluoride is employed as an insecticide.
The linking of fluorine and carbon has created some of the most chemically inert compounds known. Fluorocarbons such as Teflon have found extensive use as lubricants and bearing materials because of their low friction. Because of their inertness and heat resistance they may be used, for example, as a coating on cooking ware. Because they are not wetted by water or oils, they are sometimes used to add antisoil properties to textiles. The use of fluorite as a flux was described in 1529 by Georgius Agricola.