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Fluorite (also called fluorspar) is the mineral form of calcium fluoride, CaF 2.It belongs to the halide minerals.It crystallizes in isometric cubic habit, although octahedral and more complex isometric forms are not uncommon.
The main uses of fluoride, in terms of volume, are in the production of cryolite, Na 3 AlF 6. It is used in aluminium smelting. Formerly, it was mined, but now it is derived from hydrogen fluoride. Fluorite is used on a large scale to separate slag in steel-making. Mined fluorite (CaF 2) is a commodity chemical used in steel-making.
Many compounds, notably the common mineral fluorite (CaF 2), adopt this structure. Many compounds with formula M 2 X have an antifluorite structure. In these the locations of the anions and cations are reversed relative to fluorite (an anti-structure); the anions occupy the FCC regular sites whereas the cations occupy the tetrahedral ...
Its use began in the 1940s, following studies of children in a region where water is naturally fluoridated. It is now used widely in public water systems in the United States and some other parts of the world, such that about two-thirds of the U.S. population is exposed to fluoridated water supplies [5] and about 5.7% of people worldwide. [6]
Substantial energy is still needed for both heating the materials and the electrolysis, but it is much more energy-efficient than melting the oxides themselves. As natural cryolite is now too rare to be used for this purpose, synthetic sodium aluminium fluoride is produced from the common mineral fluorite. [citation needed]
Fluorite of the acidspar grade is used directly as an additive to ceramics and enamels, glass fibers and clouded glass, and cement, as well as in the outer coating of welding rods. [5] Acidspar is primarily used for making hydrofluoric acid, which is a chemical intermediate for most fluorine-containing compounds.
Blue John (also known as Derbyshire Spar) is a semi-precious mineral, a rare form of fluorite with bands of a purple-blue or yellowish colour. In the United Kingdom it is found only at Blue John Cavern and Treak Cliff Cavern at Castleton in Derbyshire .
Hydrogen fluoride is typically produced by the reaction between sulfuric acid and pure grades of the mineral fluorite: [14] CaF 2 + H 2 SO 4 → 2 HF + CaSO 4. About 20% of manufactured HF is a byproduct of fertilizer production, which generates hexafluorosilicic acid. This acid can be degraded to release HF thermally and by hydrolysis: H 2 SiF ...