SUGILITE

Chemical Formula: KNa2(Fe++,Mn++,Al)2Li3Si12O30
Composition: Molecular Weight = 1,028.28 gm
Potassium 3.80 % K 4.58 % K2O
Sodium 4.47 % Na 6.03 % Na2O
Lithium 2.03 % Li 4.36 % Li2O
Manganese 3.21 % Mn 4.14 % MnO
Aluminum 0.52 % Al 0.99 % Al2O3
Iron 6.52 % Fe 8.38 % FeO
Silicon 32.78 % Si 70.12 % SiO2
Oxygen 46.68 % O
______ ______
100.00 % 98.60 % = TOTAL OXIDE
Empirical Formula: KNa2Fe2+1.2Mn2+0.6Al0.2Li3Si12O30
IMA Status: Approved IMA 1976

Physical Properties
Cleavage: [0001] Indistinct
Colour: brownish yellow, violet, or reddish violet.
Density: 2.74
Diaphaniety: Transparent to Translucent
Hardness: 6-6.5
Lustre: Vitreous (Glassy)

Much, much more about sugilite! Very interesting! Metaphysicals et al at sugilite.org!