RocksdayBornite vs Chalcopyrite
How to tell them apart
A copper iron sulfide that tarnishes to brilliant purple and blue — the true 'peacock ore'.
Photo: Robert M. Lavinsky, CC BY-SA 3.0
Copper iron sulfide and the world's most important copper ore. Brassy yellow, often tarnished to rainbow purples and blues.
Photo: Robert M. Lavinsky, CC BY-SA 3.0
Quick tests
- Streak (rub on unglazed porcelain): Bornite leaves a grayish black streak; Chalcopyrite leaves greenish black.
Key differences
- Chalcopyrite is brass-yellow inside.
Side by side
| Property | Bornite | Chalcopyrite |
|---|---|---|
| Type | Mineral | Mineral |
| Mohs hardness | 3 | 3.5–4 |
| Luster | Metallic | Metallic |
| Streak | Grayish black | Greenish black |
| Colors | Purple, Blue, Brown | Gold |
| Crystal system | Orthorhombic | Tetragonal |
| Specific gravity | 4.9–5.4 | 4.1–4.3 |
| Formula | Cu₅FeS₄ | CuFeS₂ |
| Found in | Butte, Montana; Chile | Chile; Peru |
Properties that are the same for both are grayed out.
How to identify bornite
- Bronze on a fresh break, quickly tarnishing purple and blue.
- Soft — a knife scratches it.
- Usually massive, rarely crystals.
Crystal system: Orthorhombic
Full Bornite guide →How to identify chalcopyrite
- Deeper, greener yellow than pyrite.
- Iridescent tarnish on older surfaces.
- A knife scratches it (pyrite resists).
- Greenish-black streak.
Crystal system: Tetragonal
Full Chalcopyrite guide →More comparisons
Could you tell them apart from a blurry close-up?
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