Fluorite

**Chemical name:** Calcium fluoride

**Formula:** CaF₂

**Molar mass:** 78,07 g/mol

**Mohs scale hardness:** 4

**Crystal system:** Face centred cubic cell of Ca²⁺ ions, the tetrahedral cavities are occupied by ions F⁻

**Crystal habit:** Box, rarely octahedral.

**Information:** Pure calcium fluoride is a colourless crystalline substance insoluble in water. In nature, due to the content of rare earth, fluorite exhibits different colours ‒ blue, yellow, white and purple to black.

**Use:** Fluorite is used to produce hydrofluoric acid. It is used in metallurgy and glass industry. Calcium fluoride is commonly used as a material for optical purposes (production of lenses).