Comparison · Igneous Rocks
Basalt vs Scoria
Basalt and Scoria are easy to confuse because both are igneous rocks. Both sit near Mohs 6, 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 Basalt and Scoria
- Both sit near Mohs 6, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
- Luster is different: Basalt is dull while Scoria is dull, glassy.
- Basalt feels noticeably heavier for its size (specific gravity 3 versus 1.5–2.6 for Scoria).
- Hold a thin edge to the light: Basalt is opaque, Scoria is Opaque.
- They overlap in black, but Basalt also comes in gray and green and Scoria also comes in red and brown.
Basalt vs Scoria properties
| Property | Basalt | Scoria |
|---|---|---|
| Type | Igneous Rocks | Igneous Rocks |
| Mohs hardness | 6 | 5–6 |
| Luster | dull | Dull, glassy |
| Streak | Variable; test individual minerals | — |
| Transparency | opaque | Opaque |
| Specific gravity | 3 | 1.5–2.6 |
| Crystal system | varies | — |
| Common colors | Black, Dark Gray, Dark Green | Dark red, Black, Brown, Reddish brown |
| Rarity | common | common |
| Typical specimen value | $1–$30+ | $1–$75+ |
Which is more valuable?
Scoria is usually the more valuable of the two: a typical collector specimen runs about $10 against $5 for Basalt, and premium Scoria can reach $75 or more.
About Basalt
Basalt is a dark, fine-grained volcanic rock that makes up most of the ocean floor and Hawaiian Islands. It often forms distinctive columnar jointing.
About Scoria
Scoria is a dark, highly vesicular volcanic rock of basaltic to andesitic composition, riddled with gas bubbles trapped as the lava cooled and depressurized rapidly. It is denser and darker than pumice, containing thicker vesicle walls and less silica, which is why scoria typically sinks in water while pumice floats. Its red color, when present, comes from oxidized iron in the rock.
Basalt vs Scoria FAQ
Is Basalt the same as Scoria?
No. Both are igneous rocks, but they are distinct rock types with different hardness, streak or luster. Both sit near Mohs 6, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
How can you tell Basalt from Scoria?
Both sit near Mohs 6, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Luster is different: Basalt is dull while Scoria is dull, glassy. Basalt feels noticeably heavier for its size (specific gravity 3 versus 1.5–2.6 for Scoria).
Which is harder, Basalt or Scoria?
Basalt is harder: Mohs 6 against Mohs 5–6 for Scoria.
Which is more valuable, Basalt or Scoria?
Scoria is usually the more valuable of the two: a typical collector specimen runs about $10 against $5 for Basalt, and premium Scoria can reach $75 or more.
