RocksdayAzurite vs Vivianite
How to tell them apart
An intensely deep blue copper carbonate. Over time it slowly converts to green malachite, and the two are often found together.
Photo: Ivar Leidus, CC BY-SA 4.0
An iron phosphate that is nearly colorless when fresh but darkens to deep blue-green in light.
Photo: CarlesMillan, CC BY-SA 4.0
Quick tests
- Fingernail: A fingernail scratches Vivianite (Mohs 1.5–2) but not Azurite (Mohs 3.5–4).
- Acid (vinegar or dilute HCl): Azurite fizzes; Vivianite doesn't.
- Streak (rub on unglazed porcelain): Azurite leaves a light blue streak; Vivianite leaves white turning blue.
- Heft: Azurite feels noticeably heavier for its size (specific gravity 3.77–3.78 vs 2.68).
Key differences
- Azurite is harder and fizzes in acid.
Side by side
| Property | Azurite | Vivianite |
|---|---|---|
| Type | Mineral | Mineral |
| Mohs hardness | 3.5–4 | 1.5–2 |
| Luster | Vitreous | Vitreous to pearly |
| Streak | Light blue | White turning blue |
| Colors | Blue | Blue, Green, Clear |
| Crystal system | Monoclinic | Monoclinic |
| Specific gravity | 3.77–3.78 | 2.68 |
| Formula | Cu₃(CO₃)₂(OH)₂ | Fe₃(PO₄)₂·8H₂O |
| Found in | Bisbee, Arizona; Tsumeb, Namibia | Llallagua, Bolivia; Kerch, Crimea |
Properties that are the same for both are grayed out.
How to identify azurite
- Deep 'azure' blue, often with green malachite.
- Fizzes in acid.
- Soft — a knife scratches it.
- Light blue streak.
Crystal system: Monoclinic
Full Azurite guide →How to identify vivianite
- Blue-green bladed crystals that darken over time.
- Very soft and flexible.
- Often on fossils, bones or in bogs.
Crystal system: Monoclinic
Full Vivianite guide →More comparisons
Could you tell them apart from a blurry close-up?
Play today's Rocksday