Bornite
Bornite, also known as peacock ore, is a sulfide mineral with chemical composition Cu5FeS4 that crystallizes in the orthorhombic system (pseudo-cubic).
| Bornite | |
|---|---|
Lightly iridescent bornite crystal on quartz needles, from Kazakhstan Specimen size: 3.6 cm × 2.2 cm × 1.2 cm (1.42 in × 0.87 in × 0.47 in) | |
| General | |
| Category | Sulfide mineral |
| Formula (repeating unit) | Cu5FeS4 |
| IMA symbol | Bn |
| Strunz classification | 2.BA.10 |
| Crystal system | Orthorhombic |
| Crystal class | Dipyramidal (mmm) H-M symbol: (2/m 2/m 2/m) |
| Space group | Pbca |
| Unit cell | a = 10.95 Å, b = 21.862 Å, c = 10.95 Å; Z = 16 |
| Identification | |
| Formula mass | 501.88 g/mol |
| Color | Copper red, bronze brown, purple |
| Crystal habit | Granular, massive, disseminated – Crystals pseudocubic, dodecahedral, octahedral |
| Twinning | Penetration twins on [111] |
| Cleavage | Poor on [111] |
| Fracture | Uneven to subconchoidal |
| Tenacity | Brittle |
| Mohs scale hardness | 3–3.25 |
| Luster | Metallic if fresh, iridescent tarnish |
| Streak | Grayish black |
| Specific gravity | 5.06–5.08 |
| Refractive index | Opaque |
| Pleochroism | Weak but noticeable |
| Other characteristics | Magnetic after heating, iridescent |
| References | |
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