Comparison · Metamorphic Rocks
Blueschist vs Greenschist
Blueschist and Greenschist are easy to confuse because both are metamorphic rocks. Blueschist is harder (Mohs 5.5) than Greenschist (Mohs 4.5), so Blueschist will scratch Greenschist and not the other way round. A steel knife blade (Mohs 5.5) scratches it; a copper coin does not. Below is a side-by-side comparison of their properties and the quick tests that separate them.
Key differences between Blueschist and Greenschist
- Blueschist is harder (Mohs 5.5) than Greenschist (Mohs 4.5), so Blueschist will scratch Greenschist and not the other way round. A steel knife blade (Mohs 5.5) scratches it; a copper coin does not.
- Streak color differs: Blueschist leaves a variable; usually pale gray streak on unglazed porcelain, Greenschist leaves variable; usually pale greenish gray.
- They overlap in gray, green, and black, but Blueschist also comes in blue and Greenschist also comes in white.
Blueschist vs Greenschist properties
| Property | Blueschist | Greenschist |
|---|---|---|
| Type | Metamorphic Rocks | Metamorphic Rocks |
| Mohs hardness | 5.5 | 4.5 |
| Luster | silky | silky |
| Streak | Variable; usually pale gray | Variable; usually pale greenish gray |
| Transparency | opaque | opaque |
| Specific gravity | 3.1 | 2.9 |
| Crystal system | varies | varies |
| Common colors | Blue, Blue gray, Gray, Green, Black | Green, Gray green, Dark green, Black, White |
| Rarity | uncommon | common |
| Typical specimen value | $5–$150+ | $1–$75+ |
Which is more valuable?
Blueschist is usually the more valuable of the two: a typical collector specimen runs about $30 against $10 for Greenschist, and premium Blueschist can reach $150 or more.
About Blueschist
Blueschist is a blue to blue-gray metamorphic rock linked to subduction zones. Its color often comes from blue amphibole minerals such as glaucophane.
About Greenschist
Greenschist is a greenish metamorphic rock named for its common green minerals and schistose texture. It often looks green, gray-green, or dark green and may have a silky sheen.
Blueschist vs Greenschist FAQ
Is Blueschist the same as Greenschist?
No. Both are metamorphic rocks, but they are distinct rock types with different hardness, streak or luster. Blueschist is harder (Mohs 5.5) than Greenschist (Mohs 4.5), so Blueschist will scratch Greenschist and not the other way round. A steel knife blade (Mohs 5.5) scratches it; a copper coin does not.
How can you tell Blueschist from Greenschist?
Blueschist is harder (Mohs 5.5) than Greenschist (Mohs 4.5), so Blueschist will scratch Greenschist and not the other way round. A steel knife blade (Mohs 5.5) scratches it; a copper coin does not. Streak color differs: Blueschist leaves a variable; usually pale gray streak on unglazed porcelain, Greenschist leaves variable; usually pale greenish gray. They overlap in gray, green, and black, but Blueschist also comes in blue and Greenschist also comes in white.
Which is harder, Blueschist or Greenschist?
Blueschist is harder: Mohs 5.5 against Mohs 4.5 for Greenschist.
Which is more valuable, Blueschist or Greenschist?
Blueschist is usually the more valuable of the two: a typical collector specimen runs about $30 against $10 for Greenschist, and premium Blueschist can reach $150 or more.
