Crystal guide
How to Identify Peridot
(Mg,Fe)₂SiO₄ (Olivine)
Peridot is the gem variety of olivine ((Mg,Fe)₂SiO₄) in yellow-green to olive hues. Identify it by fresh grass-green color that never goes emerald-blue, strong birefringence doubling facet edges, Mohs 6.5–7, and an oily luster on rough crystals.
About Peridot
Peridot is the gem variety of olivine ((Mg,Fe)₂SiO₄) in yellow-green to olive hues. Identify it by fresh grass-green color that never goes emerald-blue, strong birefringence doubling facet edges, Mohs 6.5–7, and an oily luster on rough crystals.
Peridot is filed under crystals in the RockScan directory. Composition: Magnesium iron silicate. It forms via mantle-derived basalt and peridotite. Typical occurrence: Pakistan, Myanmar, USA (Arizona), China. For the broader method, see how to identify rock types.
Peridot properties
| Mohs hardness | 6.5–7 |
|---|---|
| Class | crystal |
| Scientific name | (Mg,Fe)₂SiO₄ (Olivine) |
| Color | Yellowish green to olive |
| Luster | Vitreous |
| Crystal system / texture | Orthorhombic |
| Composition | Magnesium iron silicate |
| Formation | Mantle-derived basalt and peridotite |
| Occurrence | Pakistan, Myanmar, USA (Arizona), China |
How to identify Peridot
- Yellow-green to olive color, even in tone without blue secondary.
- Doubled back-facet edges under a loupe (strong birefringence).
- Mohs 6.5–7; mantle-born crystals, often in basalt matrix.
Lookalikes to rule out
- Green tourmaline: Green tourmaline is harder (7–7.5) with strong pleochroism and striated prisms; peridot shows doubled facet edges from high birefringence.
- Emerald: Emerald is beryl (7.5–8) with chromium spectrum and jardin inclusions; peridot is softer olivine with a purely yellow-green hue.
- Green glass: Glass holds round bubbles with singly refractive optics; peridot doubles back-facet edges under a loupe.
Photo tips for Peridot ID
- Shoot in daylight — peridot's yellow-green glows best in sun and dulls under warm bulbs.
- Loupe-shot the doubled facet junctions; doubling is the classic peridot proof.
- Show the oily luster on rough olivine bombs when photographing matrix pieces.
Snap one specimen in natural light, then open the result in the online studio or the rock identifier app.
Peridot FAQ
How do you identify peridot?
Check yellow-green color plus doubled facet edges under magnification. Tourmaline shows pleochroism instead; glass shows bubbles.
Peridot vs emerald?
Emerald is harder beryl with bluish-green and jardin gardens; peridot is softer olivine in pure yellow-green.
Where does peridot form?
Earth's mantle — carried up in basalts and peridotites, and even found in pallasite meteorites.
How to identify peridot
Green gems blur together, but peridot owns two tells no rival shares: mantle-born yellow-green plus visible doubling. Check both:
- Yellow-green only: fresh grass to olive hue with no blue secondary — bluish green means tourmaline or emerald.
- Facet doubling: back edges split into two under a loupe; few gems double this strongly.
- Hardness 6.5–7: softer than tourmaline, emerald, and sapphire — facet edges abrade sooner.
- Oily rough: unpolished olivine shows a greasy luster in basaltic matrix.
- Photo confirm: daylight color shot plus a loupe doubling photo, then RockScan against tourmaline and glass.
Peridot vs green tourmaline vs emerald vs glass
- Green tourmaline: harder with pleochroic color shifts and striated prisms; no strong doubling.
- Emerald: harder beryl with chromium spectrum and garden inclusions.
- Green glass: bubbles, mold lines, and single refraction with no facet doubling.
Photo tips for peridot doubling
Daylight for true lime tone, then a loupe macro on facet junctions to catch the doubling. Compare tourmaline, topaz, and meteorite (pallasite connection) guides, then confirm in the online studio or rock identifier app.
Related crystals to compare
Browse all: rocks · minerals · crystals · directory · what rock is this · rock vs mineral vs crystal. Confirm with the online studio or rock identifier app.