Sodalite is a tectosilicate mineral with the formula Na ₈Cl ₂, with royal blue varieties widely used as an ornamental gemstone. Although massive sodalite samples are opaque, crystals are usually transparent to translucent. Sodalite is a member of the sodalite group with hauyne, nosean, lazurite and tugtupite.
Color: Blue, Purple
Luster: Greasy, Waxy
Crystal system: Cubic crystal system
Chemical formula: Na₈Al₆Si₆O₂₄ Cl₂
Hardness (Mohs hardness scale): 5.5 – 6