Comparison · Semi-Precious Stones vs Minerals
Opal vs Rhodonite
Opal and Rhodonite are easy to confuse. Both sit near Mohs 5.5, 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 Opal and Rhodonite
- Both sit near Mohs 5.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
- Rhodonite feels noticeably heavier for its size (specific gravity 3.6 versus 2.1 for Opal).
- They overlap in black and pink, but Opal also comes in white and blue.
- Well-formed crystals give it away: Opal is amorphous, Rhodonite is triclinic.
Opal vs Rhodonite properties
| Property | Opal | Rhodonite |
|---|---|---|
| Type | Semi-Precious Stones | Minerals |
| Mohs hardness | 5.5 | 6 |
| Luster | vitreous | vitreous |
| Streak | White | White |
| Transparency | translucent | translucent |
| Specific gravity | 2.1 | 3.6 |
| Crystal system | amorphous | triclinic |
| Common colors | White, Black, Fire, Blue, Pink | Pink, Rose, Pink with black veins |
| Rarity | uncommon | uncommon |
| Typical specimen value | $50–$10000+ | $5–$200+ |
Which is more valuable?
Opal is usually the more valuable of the two: a typical collector specimen runs about $500 against $30 for Rhodonite, and premium Opal can reach $10000 or more.
About Opal
Opal is famous for its play-of-color, caused by the diffraction of light through microscopic silica spheres. Australia produces 95% of the world's opals.
About Rhodonite
Rhodonite is a pink manganese silicate often featuring black veins of manganese oxide. It's the official gem of Massachusetts.
Opal vs Rhodonite FAQ
Is Opal the same as Rhodonite?
No. Opal is a semi-precious stone while Rhodonite is a mineral. Both sit near Mohs 5.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
How can you tell Opal from Rhodonite?
Both sit near Mohs 5.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Rhodonite feels noticeably heavier for its size (specific gravity 3.6 versus 2.1 for Opal). They overlap in black and pink, but Opal also comes in white and blue.
Which is harder, Opal or Rhodonite?
Rhodonite is harder: Mohs 6 against Mohs 5.5 for Opal.
Which is more valuable, Opal or Rhodonite?
Opal is usually the more valuable of the two: a typical collector specimen runs about $500 against $30 for Rhodonite, and premium Opal can reach $10000 or more.
