Fluorite is a mineral with a Mohs hardness of 5.0-6.0, and its crystal system is trigonal. It typically occurs as deep blue or purple color masses in hydrothermal veins, though it can also form transparent hexagonal crystals and other varieties. Fluorite may fluoresce under ultraviolet light and produce a characteristic green to violet glow.
Fluorite crystals are popular with collectors because they allow an electric current to be passed through them in either direction, preventing the build-up of static electricity or electromagnetic fields within the stone.