Geminite

General Information:
 Chemical Formula:
Cu++2As+++++2O7·3(H2O)
 Composition:
(Molecular Weight = 442.98 gm)
Copper 28.69 % Cu
Arsenic 33.83 % As
Hydrogen 1.37 % H 
Oxygen 36.12 % O 
 Empirical Formula:
Cu2As2O7·3(H2O)
 Environment:
Coatings on quartz.
 IMA Status:
Approved IMA
 Locality:
Cap Garonne mine, Var, France.
 Name Origin:
Named from the Latin gemini, twins, in allusion to the usual character of the crystals.
Physical Properties:
 Cleavage:
[001] Perfect
 Color:
light green or sea green.
 Density:
3.7 - 3.71, Average = 3.7
 Diaphaniety:
Transparent
 Habits:
Radial - Crystals radiate from a center without producing stellar forms (e.g. stibnite), Columnar - Forms columns, Twinning Common - Crystals are usually twinned.
 Hardness:
3-3.5 - Calcite-Copper Penny
 Luminescence:
Non-fluorescent.
 Luster:
Vitreous (Glassy)
 Streak:
pale green
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