RocksdayChalcopyrite vs Pyrite
How to tell them apart
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
Brassy iron sulfide famous as 'fool's gold'. It often forms startlingly perfect cubes with fine parallel lines on the faces.
Photo: Ivar Leidus, CC BY-SA 4.0
Quick tests
- Scratch glass: Pyrite scratches glass (Mohs 6–6.5); Chalcopyrite can't (Mohs 3.5–4).
Key differences
- Pyrite is paler, harder and forms cubes.
- Chalcopyrite is softer, deeper yellow and tarnishes to iridescent colors.
Side by side
| Property | Chalcopyrite | Pyrite |
|---|---|---|
| Type | Mineral | Mineral |
| Mohs hardness | 3.5–4 | 6–6.5 |
| Luster | Metallic | Metallic |
| Streak | Greenish black | Greenish black |
| Colors | Gold | Gold |
| Crystal system | Tetragonal | Cubic |
| Specific gravity | 4.1–4.3 | 4.95–5.1 |
| Formula | CuFeS₂ | FeS₂ |
| Found in | Chile; Peru | Navajún, Spain; Huanzala, Peru |
Properties that are the same for both are grayed out.
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 →How to identify pyrite
- Pale brass-yellow metallic color.
- Streak is greenish black, not gold.
- Hard and brittle — it shatters rather than flattens when struck.
- Cubes with striated faces, or twelve-sided pyritohedrons.
Crystal system: Cubic
Full Pyrite guide →More comparisons
Could you tell them apart from a blurry close-up?
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