General Information:
Chemical Formula:Ca2(Fe++,Mg)3Al2(Si7Al)O22(OH)2
Composition:(Molecular Weight = 879.70 gm)Calcium 9.11 %
CaMagnesium 2.76 %
MgAluminum 9.20 %
AlIron 12.70 %
FeSilicon 22.35 %
SiHydrogen 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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