Lazurite

Lazurite, formerly called azure spar, is a tectosilicate mineral with sulfate, sulfur and chloride, a feldspathoid and a member of the sodalite group. It crystallizes in the isometric system, although well-formed crystals are rare, and it is usually massive and forms the bulk of the gemstone lapis lazuli. It is deep blue to greenish blue, the color being due to the presence of S-3 anions, and has a Mohs hardness of 5.0 to 5.5. It is a product of contact metamorphism of limestone and is typically associated with calcite, pyrite and diopside. In this atlas it is the principal mineral that the gemstone lapis lazuli records.

Lazurite, formerly called azure spar, is a tectosilicate mineral with sulfate, sulfur and chloride, a feldspathoid and a member of the sodalite group. It crystallizes in the isometric system, although well-formed crystals are rare, and it is usually massive and forms the bulk of the gemstone lapis lazuli. It is deep blue to greenish blue, the color being due to the presence of S-3 anions, and has a Mohs hardness of 5.0 to 5.5. It is a product of contact metamorphism of limestone and is typically associated with calcite, pyrite and diopside. In this atlas it is the principal mineral that the gemstone lapis lazuli records.