RocksdayMarcasite vs Pyrite
How to tell them apart
Same chemistry as pyrite but a different crystal structure; paler and more prone to crumbling.
Photo: Didier Descouens, CC BY-SA 4.0
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
Key differences
- Pyrite is yellower and forms cubes.
Side by side
| Property | Marcasite | Pyrite |
|---|---|---|
| Type | Mineral | Mineral |
| Mohs hardness | 6–6.5 | 6–6.5 |
| Luster | Metallic | Metallic |
| Streak | Greenish black | Greenish black |
| Colors | Gold, Silver | Gold |
| Crystal system | Orthorhombic | Cubic |
| Specific gravity | 4.8–4.9 | 4.95–5.1 |
| Formula | FeS₂ | FeS₂ |
| Found in | Chalk cliffs of Dover, England; Bohemia, Czech Republic | Navajún, Spain; Huanzala, Peru |
Properties that are the same for both are grayed out.
How to identify marcasite
- Pale brass to tin-white, often in spear or cockscomb shapes.
- Nodules in chalk with radiating insides.
- May crumble to white powder in humid storage.
Crystal system: Orthorhombic
Full Marcasite 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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