The Crystal Cave

Bornite

Cu₅FeS₄

Sulfides a copper iron sulfide.
Appearance: Are rarely in cubic, dodecahedral or octahedral crystals. Forms as compact granular masses of redish bronze color, showing an iridescent purple and greenish blue surfaces.
Hardness: 3
SG: 5,7
Opaque with metalic luster.
Crystal system: Cubic.
Environment: Builds in mafic rocks with magmatic segregation. High tepmerature pegmatites and hydrothermal veins, in the oxidation of copper deposits, associated with malacite.