Natural Sodalite, 10.35 Cts. Oval , 20 x 15 MM Depth : 4.5 MM, Ash Blue, Opaque, Good , Origin : Namibia Hardness : 5.5, Specific Gravity : 2.1 - 2.3 , Refractive Index : 1.48, Chemical Composition : Na4Al3(SiO4)3Cl Treatment : Natural