RocksdayChalcopyrite vs Gold
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
A native metal that never tarnishes. In nature it occurs as nuggets, flakes in stream gravel and wires in quartz veins.
Photo: Alchemist-hp (talk) www.pse-mendelejew.de, CC BY-SA 3.0 de
Quick tests
- Streak (rub on unglazed porcelain): Chalcopyrite leaves a greenish black streak; Gold leaves golden yellow.
- Heft: Gold feels noticeably heavier for its size (specific gravity 15.5–19.3 vs 4.1–4.3).
Key differences
- Gold is malleable and leaves a gold streak.
- Chalcopyrite crumbles to a greenish-black powder.
Side by side
| Property | Chalcopyrite | Gold |
|---|---|---|
| Type | Mineral | Mineral |
| Mohs hardness | 3.5–4 | 2.5–3 |
| Luster | Metallic | Metallic |
| Streak | Greenish black | Golden yellow |
| Colors | Gold | Gold |
| Crystal system | Tetragonal | Cubic |
| Specific gravity | 4.1–4.3 | 15.5–19.3 |
| Formula | CuFeS₂ | Au |
| Found in | Chile; Peru | Witwatersrand, South Africa; Carlin Trend, Nevada |
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 gold
- Extremely heavy — sinks instantly in a gold pan.
- Bends and flattens instead of breaking.
- Golden streak.
- Stays bright yellow in shade and sun alike.
Crystal system: Cubic
Full Gold guide →More comparisons
Could you tell them apart from a blurry close-up?
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