RocksdayAtacamite vs Malachite
How to tell them apart
A copper chloride forming dark emerald-green crystals in very dry climates.
Photo: Ivar Leidus, CC BY-SA 4.0
A vivid green copper carbonate with bold light-and-dark banding. It forms where copper deposits weather near the surface.
Photo: JJ Harrison (https://www.jjharrison.com.au/), CC BY-SA 3.0
Quick tests
- Acid (vinegar or dilute HCl): Malachite fizzes; Atacamite doesn't.
- Streak (rub on unglazed porcelain): Atacamite leaves a apple green streak; Malachite leaves light green.
Key differences
- Malachite is banded and fizzes in acid.
Side by side
| Property | Atacamite | Malachite |
|---|---|---|
| Type | Mineral | Mineral |
| Mohs hardness | 3–3.5 | 3.5–4 |
| Luster | Adamantine to vitreous | Silky to dull |
| Streak | Apple green | Light green |
| Colors | Green | Green |
| Crystal system | Orthorhombic | Monoclinic |
| Specific gravity | 3.75–3.77 | 3.6–4.05 |
| Formula | Cu₂Cl(OH)₃ | Cu₂CO₃(OH)₂ |
| Found in | Atacama Desert, Chile; Burra, South Australia | Katanga, DR Congo; Ural Mountains, Russia |
Properties that are the same for both are grayed out.
How to identify atacamite
- Deep emerald to blackish green slender prisms.
- Apple-green streak.
- Doesn't fizz in acid.
Crystal system: Orthorhombic
Full Atacamite guide →How to identify malachite
- Bright green with concentric light/dark bands.
- Fizzes in acid.
- Feels heavy for a stone.
- Light green streak.
Crystal system: Monoclinic
Full Malachite guide →More comparisons
Could you tell them apart from a blurry close-up?
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