General Information:
Chemical Formula:
[ ]Fe++5Al2Si6Al2O22(OH)2
Composition:
(Molecular Weight = 941.68 gm)
Aluminum 11.46 % Al
Iron 29.65 % Fe
Silicon 17.90 % Si
Hydrogen 0.21 % H
Oxygen 40.78 % O
Empirical Formula:
Fe2+5Al4Si6O22(OH)2
IMA Status:
Approved IMA 1978
Name Origin:
Named for its composition and the original gederite location at Heas, Gedres, France.
Physical Properties:
Cleavage:
[110] Perfect, [010] Indistinct, [100] Indistinct
Color:
green, brownish green, brown, or greenish blue.
Density:
3.57
Diaphaniety:
Transparent to Subopaque
Hardness:
5.5-6 - Knife Blade-Orthoclase
Luster:
Vitreous - Silky
Streak:
gray white
More details...