Comparison · Gemstones vs Igneous Rocks
Ammolite vs Obsidian
Ammolite and Obsidian are easy to confuse. Ammolite is harder (Mohs 7) than Obsidian (Mohs 5.5), so Ammolite will scratch Obsidian and not the other way round. It is about as hard as window glass: a knife barely marks it, while a steel file (Mohs 6.5) will. Below is a side-by-side comparison of their properties and the quick tests that separate them.
Key differences between Ammolite and Obsidian
- Ammolite is harder (Mohs 7) than Obsidian (Mohs 5.5), so Ammolite will scratch Obsidian and not the other way round. It is about as hard as window glass: a knife barely marks it, while a steel file (Mohs 6.5) will.
- Streak color differs: Ammolite leaves a white to light-colored streak on unglazed porcelain, Obsidian leaves white.
- Ammolite feels noticeably heavier for its size (specific gravity 3 versus 2.4 for Obsidian).
- They overlap in multicolored, but Obsidian also comes in black, brown, and green.
Ammolite vs Obsidian properties
| Property | Ammolite | Obsidian |
|---|---|---|
| Type | Gemstones | Igneous Rocks |
| Mohs hardness | 7 | 5.5 |
| Luster | vitreous | vitreous |
| Streak | White to light-colored | White |
| Transparency | translucent | translucent |
| Specific gravity | 3 | 2.4 |
| Crystal system | varies | amorphous |
| Common colors | Various | Black, Brown, Green, Rainbow |
| Rarity | common | common |
| Typical specimen value | $10–$500+ | $5–$100+ |
Which is more valuable?
Ammolite is usually the more valuable of the two: a typical collector specimen runs about $75 against $20 for Obsidian, and premium Ammolite can reach $500 or more.
About Ammolite
Ammolite is organic gemstone formed when it mixes with fossilized shell of extinct marine ammonite.
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.
Ammolite vs Obsidian FAQ
Is Ammolite the same as Obsidian?
No. Ammolite is a gemstone while Obsidian is a igneous rock. Ammolite is harder (Mohs 7) than Obsidian (Mohs 5.5), so Ammolite will scratch Obsidian and not the other way round. It is about as hard as window glass: a knife barely marks it, while a steel file (Mohs 6.5) will.
How can you tell Ammolite from Obsidian?
Ammolite is harder (Mohs 7) than Obsidian (Mohs 5.5), so Ammolite will scratch Obsidian and not the other way round. It is about as hard as window glass: a knife barely marks it, while a steel file (Mohs 6.5) will. Streak color differs: Ammolite leaves a white to light-colored streak on unglazed porcelain, Obsidian leaves white. Ammolite feels noticeably heavier for its size (specific gravity 3 versus 2.4 for Obsidian).
Which is harder, Ammolite or Obsidian?
Ammolite is harder: Mohs 7 against Mohs 5.5 for Obsidian.
Which is more valuable, Ammolite or Obsidian?
Ammolite is usually the more valuable of the two: a typical collector specimen runs about $75 against $20 for Obsidian, and premium Ammolite can reach $500 or more.
