RocksdayDemantoid vs Olivine
To tell Demantoid from Olivine: Peridot is yellower, less fiery and not cubic.
Green andradite garnet with a diamond-like sparkle. It bends light into colors more strongly than diamond, but it is much softer.
Photo: Robert M. Lavinsky, CC BY-SA 3.0
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 is yellower, less fiery and not cubic.
Side by side
| Property | Demantoid | Olivine |
|---|---|---|
| Type | Mineral | Mineral |
| Mohs hardness | 6.5–7 | 6.5–7 |
| Luster | Adamantine | Vitreous |
| Streak | White | White |
| Colors | Green, Yellow | 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 demantoid
- Bright green with strong fire.
- Hardness only 6.5–7 — a steel file can scratch it, unlike emerald.
- Ural stones often show curving 'horsetail' fibers inside.
Crystal system: Cubic
Full Demantoid 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
Frequently asked questions
What is the difference between demantoid and olivine?
Demantoid is a mineral with a Mohs hardness of 6.5–7 and an adamantine luster, usually green or yellow. Olivine is a mineral with a Mohs hardness of 6.5–7 and a vitreous luster, usually green or yellow.
How can you tell demantoid from olivine?
Peridot is yellower, less fiery and not cubic.
Could you tell them apart from a blurry close-up?
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