General Information:
Chemical Formula:
(Mg,Fe++)5Al2Si6Al2O22(OH)2
Composition:
(Molecular Weight = 847.05 gm)
Magnesium 8.61 % Mg
Aluminum 12.74 % Al
Iron 13.19 % Fe
Silicon 19.89 % Si
Hydrogen 0.24 % H
Oxygen 45.33 % O
Empirical Formula:
Mg3Fe2+2Al2(Si6Al2O22)(OH)2
IMA Status:
Discredited IMA 1998
Name Origin:
Named for its composition and the original gederite location at Heas Valley, Gedres, France. IMA amphibole commission recommends abandoning this species name.
Physical Properties:
Cleavage:
[???] Good
Color:
gray white.
Hardness:
5-6 - Between Apatite and Orthoclase
Streak:
white
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