RocksdayAndradite vs Olivine
How to tell them apart
Calcium iron garnet. Its green gem variety, demantoid, disperses light into colors more strongly than diamond.
Photo: Didier Descouens, CC BY-SA 4.0
Olive-green silicate that makes up most of Earth's upper mantle. Gem-quality olivine is called peridot.
Photo: Robert M. Lavinsky, CC BY-SA 3.0
Key differences
- Peridot isn't as fiery and isn't cubic.
Side by side
| Property | Andradite | Olivine |
|---|---|---|
| Type | Mineral | Mineral |
| Mohs hardness | 6.5–7 | 6.5–7 |
| Luster | Adamantine to vitreous | Vitreous |
| Streak | White | White |
| Colors | Green, Yellow, Brown, Black | Green, Yellow |
| Crystal system | Cubic | Orthorhombic |
| Specific gravity | 3.8–3.9 | 3.2–4.4 |
| Formula | Ca₃Fe₂(SiO₄)₃ | (Mg,Fe)₂SiO₄ |
| Found in | Ural Mountains, Russia; Namibia | Papakōlea, Hawaii; San Carlos, Arizona |
Properties that are the same for both are grayed out.
How to identify andradite
- Very bright, almost diamond-like luster.
- Green, yellow, brown or black dodecahedral crystals.
- Hardness 6.5–7.
Crystal system: Cubic
Full Andradite guide →How to identify olivine
- Bottle- to olive-green glassy grains.
- Often as sugary green clumps in black basalt.
- No cleavage — breaks like glass.
- Hard enough to scratch glass.
Crystal system: Orthorhombic
Full Olivine guide →More comparisons
Could you tell them apart from a blurry close-up?
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