Comparison · Igneous Rocks
Andesite vs Rhyolite
Andesite and Rhyolite are easy to confuse because both are igneous rocks. Both sit near Mohs 5–6, 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 Andesite and Rhyolite
- Both sit near Mohs 5–6, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
- They overlap in gray and brown, but Andesite also comes in green and black and Rhyolite also comes in pink, red, white, and multicolored.
Andesite vs Rhyolite properties
| Property | Andesite | Rhyolite |
|---|---|---|
| Type | Igneous Rocks | Igneous Rocks |
| Mohs hardness | 5–6 | 5.5–7 |
| Luster | Dull groundmass with vitreous phenocrysts | Dull to vitreous (glassy groundmass) |
| Transparency | Opaque | Opaque |
| Specific gravity | 2.5–2.8 | 2.35–2.7 |
| Common colors | Gray, Dark gray, Greenish gray, Brown, Black | Pink, Gray, Tan, Red, White, Banded |
| Rarity | common | common |
| Typical specimen value | $1–$75+ | $1–$75+ |
Which is more valuable?
Typical specimens of Andesite and Rhyolite trade in a similar range, around $10.
About Andesite
Andesite is a fine-grained, intermediate volcanic rock formed from lava with a silica content between basalt and rhyolite, typically 57 to 63 percent. It is named for the Andes Mountains, where it makes up much of the volcanic arc, and its groundmass is usually too fine to identify individual minerals without magnification. Andesite forms at convergent plate boundaries where oceanic crust melts beneath continental or island arcs.
About Rhyolite
Rhyolite is a fine-grained volcanic igneous rock chemically equivalent to granite but formed by rapid cooling of silica-rich lava at or near Earth's surface rather than slow crystallization underground. Its high silica content makes rhyolitic magma extremely viscous, often producing explosive eruptions and distinctive flow-banded textures as the sticky lava moves sluggishly before solidifying. Rhyolite typically appears pale gray, pink, or tan and frequently contains visible bands or streaks recording its flow history.
Andesite vs Rhyolite FAQ
Is Andesite the same as Rhyolite?
No. Both are igneous rocks, but they are distinct rock types with different hardness, streak or luster. Both sit near Mohs 5–6, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
How can you tell Andesite from Rhyolite?
Both sit near Mohs 5–6, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. They overlap in gray and brown, but Andesite also comes in green and black and Rhyolite also comes in pink, red, white, and multicolored.
Which is harder, Andesite or Rhyolite?
Rhyolite is harder: Mohs 5.5–7 against Mohs 5–6 for Andesite.
Which is more valuable, Andesite or Rhyolite?
Typical specimens of Andesite and Rhyolite trade in a similar range, around $10.
