Fluorite (fluorine) Fluorescent sample with large crystals 4 to 6 cm The crystal system is cubic. Crystals are cubes or octahedra, often twinned. The habit can be granular, massive, or compact. Perfect octahedral cleavage. Conchoidal fracture. It is often associated with quartz, calcite, dolomite, galena, pyrite, chalcopyrite, sphalerite, barite... Chemical formula: CaF2. Hardness: 4. System: Cubic, sometimes octahedral. ... info ... mode= Add to basket