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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