Cyanite (also called distene), the chemical formula of Al2SiO5, is a tri-clone mineral. Hardness 5.5 - 7 Mohs scale. The name of the mineral comes from the Greek word κυανος (kýanos) - blue, according to the color of the crystals. It is used as a raw material for the production of fireproof and acid resistant materials - insulators.
Thanks to its beautiful blue crystals, it is also popular with collectors. Sometimes it is also used as a precious stone (cabochons, facet cuts).