Lazurite - Na₃Ca(Si₃Al₃)O₁₂S

Habit: Deep blue, azure, violet blue or greenish blue. Dodecahedral crystals or more rarely cubes; also granular, disseminated or massive. Vitreous luster; translucent to opaque. Light blue streak.

Environment: A contact metamorphic mineral found in limestones.

Etymology: From its resemblance in color to the mineral azurite, whose name comes from the Persian lazhward, meaning "blue."

Lazurite is usually massive and forms the main component of lapis lazuli, a popular bright blue ornamental material that should be classified as a rock rather than a mineral. Most lapis lazuli also contains calcite (typically white) and pyrite (metallic yellow gold), and usually some haüyne and sodalite (also blue) as well. Lapis has been used as a gemstone for millennia; the famous mask of Tutankhamen, for example, has lapis lazuli inlays.