Comparison · Igneous Rocks
Obsidian vs Rainbow Obsidian
Obsidian and Rainbow Obsidian are easy to confuse because both are igneous rocks. 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 Obsidian and Rainbow Obsidian
- Both sit near Mohs 5.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
- Hold a thin edge to the light: Obsidian is translucent, Rainbow Obsidian is opaque.
- They overlap in black, green, and multicolored, but Obsidian also comes in brown and Rainbow Obsidian also comes in purple and yellow.
Obsidian vs Rainbow Obsidian properties
| Property | Obsidian | Rainbow Obsidian |
|---|---|---|
| Type | Igneous Rocks | Igneous Rocks |
| Mohs hardness | 5.5 | 5.5 |
| Luster | vitreous | vitreous |
| Streak | White | White |
| Transparency | translucent | opaque |
| Specific gravity | 2.4 | 2.4 |
| Crystal system | amorphous | amorphous |
| Common colors | Black, Brown, Green, Rainbow | Black with rainbow sheen, Purple, Green, Gold |
| Rarity | common | uncommon |
| Typical specimen value | $5–$100+ | $10–$200+ |
Which is more valuable?
Rainbow Obsidian is usually the more valuable of the two: a typical collector specimen runs about $50 against $20 for Obsidian, and premium Rainbow Obsidian can reach $200 or more.
About Obsidian
Obsidian is a naturally occurring volcanic glass formed from rapidly cooled lava. Its sharp edges made it invaluable for ancient tools and weapons.
About Rainbow Obsidian
Rainbow obsidian is a type of volcanic glass that displays bands of colorful iridescence when polished and viewed in bright light.
Obsidian vs Rainbow Obsidian FAQ
Is Obsidian the same as Rainbow Obsidian?
No. Both are igneous rocks, but they are distinct rock types with different hardness, streak or luster. 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 Obsidian from Rainbow Obsidian?
Both sit near Mohs 5.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Hold a thin edge to the light: Obsidian is translucent, Rainbow Obsidian is opaque. They overlap in black, green, and multicolored, but Obsidian also comes in brown and Rainbow Obsidian also comes in purple and yellow.
Which is harder, Obsidian or Rainbow Obsidian?
They are about equally hard, both near Mohs 5.5.
Which is more valuable, Obsidian or Rainbow Obsidian?
Rainbow Obsidian is usually the more valuable of the two: a typical collector specimen runs about $50 against $20 for Obsidian, and premium Rainbow Obsidian can reach $200 or more.
