General Information:
Chemical Formula:
Ca2(Fe++,Mg)3Al2(Si7Al)O22(OH)2
Composition:
(Molecular Weight = 879.70 gm)
Calcium 9.11 % Ca
Magnesium 2.76 % Mg
Aluminum 9.20 % Al
Iron 12.70 % Fe
Silicon 22.35 % Si
Hydrogen 0.23 % H
Oxygen 43.65 % O
Empirical Formula:
Ca2Fe2+2MgAl3Si7O22(OH)2
IMA Status:
Approved IMA 1978
Name Origin:
Named for its composition and for Gustav Tschermak von Sessenegg (1836-1927), Austrian mineralogist.
Physical Properties:
Diaphaniety:
Transparent to Translucent
Hardness:
5-6 - Between Apatite and Orthoclase
Luster:
Vitreous (Glassy)
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