Calcium fluoride is the inorganic compound with the formula CaF<sub>2</sub>. This ioniccompound of calcium and fluorine occurs naturally as the mineral fluorite (also called fluorspar). It is the source of most of the world's fluorine. This insoluble solid adopts a cubic structure wherein calcium is coordinated to eight fluoride anions and each F<sup>−</sup> ion is surrounded by four Ca<sup>2+</sup> ions. Although perfectly packed crystalline samples are colorless, the mineral is often deeply colored due to the presence of F-centers.
The mineral fluorspar is abundant, widespread, and mainly of interest as a precursor to HF. Thus, little motivation exists for the preparation of CaF<sub>2</sub>. High purity CaF<sub>2</sub> is produced by treating calcium carbonate with hydrofluoric acid:
Naturally occurring CaF<sub>2</sub> is the principal source of hydrogen fluoride, a commodity chemical used to produce a wide range of materials. Hydrogen fluoride is liberated from the mineral by the action of concentrated sulfuric......