Calcium fluoride (Chemical formula: CaF2) is the fluoride, white crystal, insoluble in water, crystal is transparent. It is the main component of fluorite minerals, but also the main source of fluorine, can be used to produce hydrogen fluoride, fluorine gas, fluoride and other important chemical reagents, annual output reached 500,000 tons (1990 's late). The calcium fluoride type structure is an important structure in the crystal structure. In the cube cell, the ca2+ and the eight f− were cube-shaped, f− and four ca2+ with tetrahedron-type ligands. Because of the presence of f in the lattice, calcium fluoride in the mineral is often very deep in color. Hydrogen fluoride is made from calcium fluoride in industry and in laboratories. When calcium fluoride reacts with concentrated sulfuric acid in a lead dish, hydrogen fluoride gas is released: CaF2 (s) + H2SO4 (L) →caso4 (s) + 2 HF (g) Hydrogen fluoride is a very important intermediate in chemical industry, it can be used to prepare hydrofluoric acid, and it is also the raw material for producing organic fluorine compound and fluoride and many other chemical reagents.