RocksdayCinnabar vs Realgar
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
A bright orange-red arsenic sulfide. Toxic, and it slowly crumbles to yellow powder in light.
Photo: Robert M. Lavinsky, CC BY-SA 3.0
Quick tests
- Streak (rub on unglazed porcelain): Cinnabar leaves a scarlet streak; Realgar leaves orange-red.
- Heft: Cinnabar feels noticeably heavier for its size (specific gravity 8.1–8.2 vs 3.5–3.6).
Key differences
- Cinnabar is denser with a scarlet streak.
Side by side
| Property | Cinnabar | Realgar |
|---|---|---|
| Type | Mineral | Mineral |
| Mohs hardness | 2–2.5 | 1.5–2 |
| Luster | Adamantine to dull | Resinous |
| Streak | Scarlet | Orange-red |
| Colors | Red | Red, Orange |
| Crystal system | Trigonal | Monoclinic |
| Specific gravity | 8.1–8.2 | 3.5–3.6 |
| Formula | HgS | As₄S₄ |
| Found in | Almadén, Spain; Guizhou, China | Getchell mine, Nevada; Shimen, Hunan, China |
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 realgar
- Orange-red with a resinous luster.
- Very soft.
- Orange streak; often with yellow orpiment.
Crystal system: Monoclinic
Full Realgar guide →More comparisons
Could you tell them apart from a blurry close-up?
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