Gerdtremmelite

General Information:
 Chemical Formula:
ZnAl2(AsO4)(OH)5
 Composition:
(Molecular Weight = 343.31 gm)
Aluminum 15.72 % Al
Zinc 19.05 % Zn
Arsenic 21.82 % As
Hydrogen 1.47 % H 
Oxygen 41.94 % O 
 Empirical Formula:
ZnAl2(AsO4)(OH)5
 Environment:
Deeply oxidized ore zone at Tsumeb.
 IMA Status:
Approved IMA 1985
 Locality:
Tsumeb, Namibia.
 Name Origin:
Named for Gerd Tremmel, who first recognized the mineral.
Physical Properties:
 Cleavage:
None
 Color:
brown, yellowish brown, or dark brown.
 Diaphaniety:
Transparent
 Habits:
Spherical - Spherical, rounded aggregates., Tabular - Form dimensions are thin in one direction.,
 Luminescence:
Non-fluorescent.
 Luster:
Adamantine
 Streak:
white
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