General Information:
Chemical Formula:
Cu5FeS4
Composition:
(Molecular Weight = 501.84 gm)
Iron 11.13 % Fe
Copper 63.31 % Cu
Sulfur 25.56 % S
Empirical Formula:
Cu5Fe2+S4
Environment:
Disseminated in igneous intrusions and a primary and secondary mineral in copper ore veins.
IMA Status:
Approved IMA 1960
Locality:
Cornwall, England and Arizona porphyry copper deposits.
Name Origin:
Named after the Austrian mineralogist, I. von Born (1742-1791).
Physical Properties:
Cleavage:
[111] Imperfect
Color:
copper red, bronze brown, or purple.
Density:
4.9 - 5.3, Average = 5.09
Diaphaniety:
Opaque
Habits:
Massive - Granular - Common texture observed in granite and other igneous rock., Reniform - "Kidney like" in shape (e.g.. hematite)., Granular - Generally occurs as anhedral to subhed ral crystals in matrix.
Hardness:
3 - Calcite
Luminescence:
None.
Luster:
Metallic
Streak:
grayish black
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