Comparison · Igneous Rocks vs Silicate Minerals
Obsidian vs Schorl
Obsidian and Schorl are easy to confuse. Schorl is harder (Mohs 7) than Obsidian (Mohs 5.5), so Schorl 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 Obsidian and Schorl
- Schorl is harder (Mohs 7) than Obsidian (Mohs 5.5), so Schorl 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: Obsidian leaves a white streak on unglazed porcelain, Schorl leaves white to grayish.
- Schorl feels noticeably heavier for its size (specific gravity 3.1 versus 2.4 for Obsidian).
- Hold a thin edge to the light: Obsidian is translucent, Schorl is opaque.
- They overlap in black and brown, but Obsidian also comes in green and multicolored.
- Well-formed crystals give it away: Obsidian is amorphous, Schorl is trigonal.
Obsidian vs Schorl properties
| Property | Obsidian | Schorl |
|---|---|---|
| Type | Igneous Rocks | Silicate Minerals |
| Mohs hardness | 5.5 | 7 |
| Luster | vitreous | vitreous |
| Streak | White | White to grayish |
| Transparency | translucent | opaque |
| Specific gravity | 2.4 | 3.1 |
| Crystal system | amorphous | trigonal |
| Common colors | Black, Brown, Green, Rainbow | Black, Bluish black, Brownish black |
| Rarity | common | common |
| Typical specimen value | $5–$100+ | $5–$400+ |
Which is more valuable?
Schorl is usually the more valuable of the two: a typical collector specimen runs about $50 against $20 for Obsidian, and premium Schorl can reach $400 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 Schorl
Schorl is the common black, iron-rich member of the tourmaline group. It forms striated prismatic crystals with a rounded triangular cross-section and is by far the most abundant tourmaline species in nature.
Obsidian vs Schorl FAQ
Is Obsidian the same as Schorl?
No. Obsidian is a igneous rock while Schorl is a silicate mineral. Schorl is harder (Mohs 7) than Obsidian (Mohs 5.5), so Schorl 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 Obsidian from Schorl?
Schorl is harder (Mohs 7) than Obsidian (Mohs 5.5), so Schorl 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: Obsidian leaves a white streak on unglazed porcelain, Schorl leaves white to grayish. Schorl feels noticeably heavier for its size (specific gravity 3.1 versus 2.4 for Obsidian).
Which is harder, Obsidian or Schorl?
Schorl is harder: Mohs 7 against Mohs 5.5 for Obsidian.
Which is more valuable, Obsidian or Schorl?
Schorl is usually the more valuable of the two: a typical collector specimen runs about $50 against $20 for Obsidian, and premium Schorl can reach $400 or more.
