Comparison · Metamorphic Rocks
Amphibolite vs Skarn
Amphibolite and Skarn are easy to confuse because both are metamorphic 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 Amphibolite and Skarn
- Both sit near Mohs 5.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
- Streak color differs: Amphibolite leaves a variable; usually pale gray to white streak on unglazed porcelain, Skarn leaves variable by mineral content.
- They overlap in black, green, gray, white, and red, but Skarn also comes in brown.
Amphibolite vs Skarn properties
| Property | Amphibolite | Skarn |
|---|---|---|
| Type | Metamorphic Rocks | Metamorphic Rocks |
| Mohs hardness | 5.5 | 5.5 |
| Luster | dull | dull |
| Streak | Variable; usually pale gray to white | Variable by mineral content |
| Transparency | opaque | opaque |
| Specific gravity | 3 | 3.1 |
| Crystal system | varies | varies |
| Common colors | Black, Dark green, Gray, White, Red | Green, Brown, White, Gray, Red, Black |
| Rarity | common | uncommon |
| Typical specimen value | $1–$75+ | $2–$150+ |
Which is more valuable?
Skarn is usually the more valuable of the two: a typical collector specimen runs about $20 against $10 for Amphibolite, and premium Skarn can reach $150 or more.
About Amphibolite
Amphibolite is a dark, tough metamorphic rock made mostly of amphibole and plagioclase. It often appears black to dark green and may contain red garnets.
About Skarn
Skarn is a calc-silicate metamorphic rock formed where hot intrusive fluids alter carbonate rocks. It can be green, brown, white, red, or mixed and may contain garnet, pyroxene, epidote, or ore minerals.
Amphibolite vs Skarn FAQ
Is Amphibolite the same as Skarn?
No. Both are metamorphic 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 Amphibolite from Skarn?
Both sit near Mohs 5.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Streak color differs: Amphibolite leaves a variable; usually pale gray to white streak on unglazed porcelain, Skarn leaves variable by mineral content. They overlap in black, green, gray, white, and red, but Skarn also comes in brown.
Which is harder, Amphibolite or Skarn?
They are about equally hard, both near Mohs 5.5.
Which is more valuable, Amphibolite or Skarn?
Skarn is usually the more valuable of the two: a typical collector specimen runs about $20 against $10 for Amphibolite, and premium Skarn can reach $150 or more.
