General Information:
Chemical Formula:
Cu2S
Composition:
(Molecular Weight = 159.16 gm)
Copper 79.85 % Cu
Sulfur 20.15 % S
Empirical Formula:
Cu2S
Environment:
Secondary mineral in or near the oxidized zone of copper sulfide deposits.
Locality:
Cornwall, England and Butte, Montana.
Name Origin:
From the Greek, meaning chalkos, "copper".
Physical Properties:
Cleavage:
[110] Indistinct
Color:
blue black, gray, black, black gray, or steel gray.
Density:
5.5 - 5.8, Average = 5.65
Diaphaniety:
Opaque
Habits:
Massive - Uniformly indistinguishable crystals forming large masses., Granular - Generally occurs as anhedral to subhedral crystals in matrix., Euhedral Crystals - Occurs as well-form ed crystals showing good external form.
Hardness:
2.5-3 - Finger Nail-Calcite
Luminescence:
None.
Luster:
Metallic
Streak:
grayish black
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