Cryoliitti

Cryoliitti, known in English as cryolite, is a rare fluoride mineral with the chemical formula Na3AlF6. It forms colorless to white or pale-yellow crystals and is typically found as translucent to opaque granular masses or crystal aggregates. The mineral is relatively soft, with a Mohs hardness around 2.5 to 3, and has a vitreous luster.

Occurrence and distribution: Cryolite is best known from the Ivigtut deposit in southwestern Greenland, historically its most important source. It forms in fluoride-rich, aluminous rocks and is commonly associated with other halide minerals. Outside Greenland, cryolite occurs only in minor, scattered localities and is not mined on a commercial scale.

Industrial history and applications: Cryolite is famous for its role in the electrolytic production of aluminum. In the Hall-Héluot process, natural cryolite acted as a solvent for alumina and helped lower the melting point and improve conductivity of the molten bath. Although cryolite was once a major industrial raw material, the development of synthetic cryolite and alternative fluxes reduced the reliance on natural cryolite, and large-scale mining declined. Today, cryolite is primarily of historical and mineralogical interest, with small quantities produced for collectors, research, and specialized applications.

Notes on handling: As a fluoride-bearing mineral, cryolite should be handled with care to avoid inhalation of dust and exposure to fluorides, following standard mineralogical and laboratory safety practices.