Fluorite

**Chemical name:** Calcium fluoride **Molecular formula:** CaF₂ **Molar mass:** 78.07 g/mol **Mohs scale hardness:** 4 **Crystal system:** Face-centerd cubic lattice of Ca²⁺ ions, with F⁻ ions occupying the tetrahedral cavities. **Crystal habit:** Typically forms cubic crystals, occasionally exhibiting octahedral shapes. **Description:** Pure calcium fluoride is a colorless crystalline substance that is insoluble in water. In nature, the presence of trace amounts of rare earth elements gives fluorite a variety of colors, ranging from blue, yellow and white to purple and even black. **Applications:** Fluorite (calcium fluoride) is used in the production of hydrofluoric acid. It is also used in metallurgy and the glass industry. Additionally, because of its optical properties, calcium fluoride is commonly used as a material for manufacturing lenses and other optical components.