RocksdayPentlandite vs Pyrite
How to tell them apart
The main ore of nickel, a bronze-yellow sulfide usually intergrown with pyrrhotite.
Photo: John Sobolewski (JSS), CC BY 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); Pentlandite can't (Mohs 3.5–4).
- Streak (rub on unglazed porcelain): Pentlandite leaves a bronze-brown streak; Pyrite leaves greenish black.
Key differences
- Pyrite is harder.
Side by side
| Property | Pentlandite | Pyrite |
|---|---|---|
| Type | Mineral | Mineral |
| Mohs hardness | 3.5–4 | 6–6.5 |
| Luster | Metallic | Metallic |
| Streak | Bronze-brown | Greenish black |
| Colors | Gold, Brown | Gold |
| Crystal system | Cubic | Cubic |
| Specific gravity | 4.6–5 | 4.95–5.1 |
| Formula | (Fe,Ni)₉S₈ | FeS₂ |
| Found in | Sudbury, Ontario; Norilsk, Russia | Navajún, Spain; Huanzala, Peru |
Properties that are the same for both are grayed out.
How to identify pentlandite
- Light bronze-yellow metallic.
- Not magnetic.
- Usually as grains within pyrrhotite.
Crystal system: Cubic
Full Pentlandite 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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