Calcium fluoride

Calcium fluoride is the inorganic compound with the formula CaF₂. This ionic compound 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⁻ ion is surrounded by four Ca²⁺ ions. Although perfectly packed crystalline samples are colorless, the mineral is often deeply colored due to the presence of F-centers.

Chemical structure

Preparation

The mineral fluorspar is abundant, widespread, and mainly of interest as a precursor to HF. Thus, little motivation exists for the preparation of CaF₂. High purity CaF₂ is produced by treating calcium carbonate with hydrofluoric acid:

CaCO₃ + 2 HF → CaF₂ + CO₂ + H₂O

Source of HF

Naturally occurring CaF₂ 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...... ...
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