Comparison · Minerals vs Semi-Precious Stones
Forsterite vs Peridot
Forsterite and Peridot are easy to confuse. Both sit near Mohs 6.5–7, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Below is a side-by-side comparison of their properties and the quick tests that separate them.
Key differences between Forsterite and Peridot
- Both sit near Mohs 6.5–7, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
- Hold a thin edge to the light: Forsterite is Transparent to translucent, Peridot is transparent.
- They overlap in green and yellow, but Forsterite also comes in clear.
- Well-formed crystals give it away: Forsterite is Orthorhombic, Peridot is orthorhombic.
Forsterite vs Peridot properties
| Property | Forsterite | Peridot |
|---|---|---|
| Type | Minerals | Semi-Precious Stones |
| Mohs hardness | 6.5–7 | 6.5 |
| Luster | Vitreous | vitreous |
| Streak | White | White |
| Transparency | Transparent to translucent | transparent |
| Specific gravity | 3.2–3.3 | 3.3 |
| Crystal system | Orthorhombic | orthorhombic |
| Common colors | Pale yellow-green, Olive green, Colorless | Yellow-Green, Olive Green, Lime Green |
| Rarity | common | uncommon |
| Typical specimen value | $2–$150+ | $50–$2000+ |
Which is more valuable?
Peridot is usually the more valuable of the two: a typical collector specimen runs about $200 against $20 for Forsterite, and premium Peridot can reach $2000 or more.
About Forsterite
Forsterite is the magnesium-rich end member of the olivine mineral series, with the formula Mg2SiO4, and its gem-quality transparent green variety is known as peridot. It crystallizes directly from magnesium-rich magma and is one of the first minerals to form as basaltic and ultramafic melts cool. Forsterite is abundant in Earth's upper mantle, where the olivine-rich rock peridotite is believed to make up much of that layer.
About Peridot
Peridot is the gem variety of olivine, one of the most common minerals in Earth's mantle. Its distinctive yellow-green color comes from iron.
Forsterite vs Peridot FAQ
Is Forsterite the same as Peridot?
No. Forsterite is a mineral while Peridot is a semi-precious stone. Both sit near Mohs 6.5–7, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
How can you tell Forsterite from Peridot?
Both sit near Mohs 6.5–7, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Hold a thin edge to the light: Forsterite is Transparent to translucent, Peridot is transparent. They overlap in green and yellow, but Forsterite also comes in clear.
Which is harder, Forsterite or Peridot?
They are about equally hard, both near Mohs 6.5–7.
Which is more valuable, Forsterite or Peridot?
Peridot is usually the more valuable of the two: a typical collector specimen runs about $200 against $20 for Forsterite, and premium Peridot can reach $2000 or more.
