Ferrogedrite

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
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