RocksdayCinnabar vs Cuprite
How to tell them apart
Mercury sulfide and the main ore of mercury: bright scarlet, soft and very heavy. Toxic — handle with care.
Photo: H. Zell, CC BY-SA 3.0
Copper oxide forming deep red cubes and octahedrons, sometimes as hair-like 'chalcotrichite'.
Photo: Didier Descouens, CC BY-SA 3.0
Quick tests
- Fingernail: A fingernail scratches Cinnabar (Mohs 2–2.5) but not Cuprite (Mohs 3.5–4).
- Streak (rub on unglazed porcelain): Cinnabar leaves a scarlet streak; Cuprite leaves brownish red.
- Heft: Cinnabar feels noticeably heavier for its size (specific gravity 8.1–8.2 vs 6.1–6.15).
Key differences
- Cinnabar is softer with a scarlet streak.
Side by side
| Property | Cinnabar | Cuprite |
|---|---|---|
| Type | Mineral | Mineral |
| Mohs hardness | 2–2.5 | 3.5–4 |
| Luster | Adamantine to dull | Adamantine to submetallic |
| Streak | Scarlet | Brownish red |
| Colors | Red | Red, Black |
| Crystal system | Trigonal | Cubic |
| Specific gravity | 8.1–8.2 | 6.1–6.15 |
| Formula | HgS | Cu₂O |
| Found in | Almadén, Spain; Guizhou, China | Onganja, Namibia; Bisbee, Arizona |
Properties that are the same for both are grayed out.
How to identify cinnabar
- Bright scarlet red with a scarlet streak.
- Very heavy.
- Soft — a fingernail or coin scratches it.
- Often coats white quartz or dolomite.
Crystal system: Trigonal
Full Cinnabar guide →How to identify cuprite
- Deep red, glinting crystals that can look almost black.
- Heavy.
- Brownish-red streak.
Crystal system: Cubic
Full Cuprite guide →More comparisons
Could you tell them apart from a blurry close-up?
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