Comparison · Igneous Rocks
Basaltic Andesite vs Ignimbrite
Basaltic Andesite and Ignimbrite 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 Basaltic Andesite and Ignimbrite
- Both sit near Mohs 6, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
- Streak color differs: Basaltic Andesite leaves a gray to dark gray streak on unglazed porcelain, Ignimbrite leaves variable; often light gray or tan.
- Basaltic Andesite feels noticeably heavier for its size (specific gravity 2.85 versus 2.25 for Ignimbrite).
- They overlap in gray, black, brown, and red, but Ignimbrite also comes in pink and white.
Basaltic Andesite vs Ignimbrite properties
| Property | Basaltic Andesite | Ignimbrite |
|---|---|---|
| Type | Igneous Rocks | Igneous Rocks |
| Mohs hardness | 6 | 6 |
| Luster | dull | dull |
| Streak | Gray to dark gray | Variable; often light gray or tan |
| Transparency | opaque | opaque |
| Specific gravity | 2.85 | 2.25 |
| Crystal system | varies | varies |
| Common colors | Dark gray, Black, Brown, Red brown, Gray | Tan, Pink, Gray, White, Red brown, Black |
| Rarity | common | common |
| Typical specimen value | $1–$75+ | $1–$75+ |
Which is more valuable?
Typical specimens of Basaltic Andesite and Ignimbrite trade in a similar range, around $10.
About Basaltic Andesite
Basaltic andesite is a dark volcanic rock between basalt and andesite in composition. It can look fine-grained, dark gray to black, and may contain small crystals or vesicles.
About Ignimbrite
Ignimbrite is a volcanic rock formed from hot pyroclastic flows. It can look like tuff with pumice fragments, ash, crystals, and sometimes flattened streaks from welding.
Basaltic Andesite vs Ignimbrite FAQ
Is Basaltic Andesite the same as Ignimbrite?
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 Basaltic Andesite from Ignimbrite?
Both sit near Mohs 6, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Streak color differs: Basaltic Andesite leaves a gray to dark gray streak on unglazed porcelain, Ignimbrite leaves variable; often light gray or tan. Basaltic Andesite feels noticeably heavier for its size (specific gravity 2.85 versus 2.25 for Ignimbrite).
Which is harder, Basaltic Andesite or Ignimbrite?
They are about equally hard, both near Mohs 6.
Which is more valuable, Basaltic Andesite or Ignimbrite?
Typical specimens of Basaltic Andesite and Ignimbrite trade in a similar range, around $10.
