Comparison · Metamorphic Rocks
Amphibolite vs Metaconglomerate
Amphibolite and Metaconglomerate are easy to confuse because both are metamorphic rocks. Metaconglomerate is harder (Mohs 6.5) than Amphibolite (Mohs 5.5), so Metaconglomerate will scratch Amphibolite 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 Amphibolite and Metaconglomerate
- Metaconglomerate is harder (Mohs 6.5) than Amphibolite (Mohs 5.5), so Metaconglomerate will scratch Amphibolite 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: Amphibolite leaves a variable; usually pale gray to white streak on unglazed porcelain, Metaconglomerate leaves variable by pebbles and matrix.
- They overlap in black, gray, white, and red, but Amphibolite also comes in green and Metaconglomerate also comes in brown.
Amphibolite vs Metaconglomerate properties
| Property | Amphibolite | Metaconglomerate |
|---|---|---|
| Type | Metamorphic Rocks | Metamorphic Rocks |
| Mohs hardness | 5.5 | 6.5 |
| Luster | dull | dull |
| Streak | Variable; usually pale gray to white | Variable by pebbles and matrix |
| Transparency | opaque | opaque |
| Specific gravity | 3 | 2.65 |
| Crystal system | varies | varies |
| Common colors | Black, Dark green, Gray, White, Red | Gray, White, Tan, Red, Brown, Black |
| Rarity | common | uncommon |
| Typical specimen value | $1–$75+ | $1–$75+ |
Which is more valuable?
Typical specimens of Amphibolite and Metaconglomerate trade in a similar range, around $10.
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 Metaconglomerate
Metaconglomerate is a metamorphosed conglomerate with rounded pebbles or cobbles in a recrystallized matrix. Pebbles may appear stretched, flattened, or locked into a hard metamorphic rock.
Amphibolite vs Metaconglomerate FAQ
Is Amphibolite the same as Metaconglomerate?
No. Both are metamorphic rocks, but they are distinct rock types with different hardness, streak or luster. Metaconglomerate is harder (Mohs 6.5) than Amphibolite (Mohs 5.5), so Metaconglomerate will scratch Amphibolite 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 Amphibolite from Metaconglomerate?
Metaconglomerate is harder (Mohs 6.5) than Amphibolite (Mohs 5.5), so Metaconglomerate will scratch Amphibolite 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: Amphibolite leaves a variable; usually pale gray to white streak on unglazed porcelain, Metaconglomerate leaves variable by pebbles and matrix. They overlap in black, gray, white, and red, but Amphibolite also comes in green and Metaconglomerate also comes in brown.
Which is harder, Amphibolite or Metaconglomerate?
Metaconglomerate is harder: Mohs 6.5 against Mohs 5.5 for Amphibolite.
Which is more valuable, Amphibolite or Metaconglomerate?
Typical specimens of Amphibolite and Metaconglomerate trade in a similar range, around $10.
