Ussingite

General Information: Chemical Formula:Na2AlSi3O8(OH) Composition:(Molecular Weight = 302.22 gm)Sodium 15.21 % NaAluminum 8.93 % AlSilicon 27.88 % SiHydrogen 0.33 % H Oxygen 47.65 % O  Empirical Formula: Na2AlSi3O8(OH) Environment:Pegmatites. Locality:Kangerdluarusuk, Greenland.Physical Properties: Cleavage:[???] Good, [???] Good, [???] Good Color:white, light violet red, dark violet red, pink, or reddish violet. Density:2.46 - 2.5, Average = 2.48 Diaphaniety:Transparent Habits:Massive - Uniformly indistinguishable crystals forming large masses., , Hardness:6.5 - Pyrite Luster:Vitreous (Glassy) Streak:whiteMore details...