Lazurite is a tectosilicate mineral with sulfate, sulfur and chloride with formula (Na, Ca)₈[(S, Cl, SO₄, OH)₂|]. It is a feldspathoid and a member of the sodalite group. Lazurite crystallizes in the isometric system although well‐formed crystals are rare.
Luster: Vitreous
Color: Deep blue, azure, violet-blue, greenish blue
Refractive index: 1.502–1.522
Crystal class: Hextetrahedral (43m); H-M symbol: (4 3m)
Crystal habit: Crystals occur as dodecahedra, or rarely cubes; granular, disseminated, or massive
Crystal system: Isometric
Fracture: Uneven
Lazurite is famous for its gem form, Lapis Lazuli. Lapis Lazuli, casually called by its shortened name Lapis, is the gemstone form of Lazurite that is associated with white Calcite and sparkling Pyrite. The name Lazurite is derived from the term "Lazaward", which means heaven in Arabic, alluding to its blue color.
