Comparison · Igneous Rocks
Granite vs Pumice
Granite and Pumice are easy to confuse because both are igneous rocks. Granite is harder (Mohs 6.5) than Pumice (Mohs 5–6), so Granite will scratch Pumice 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 Granite and Pumice
- Granite is harder (Mohs 6.5) than Pumice (Mohs 5–6), so Granite will scratch Pumice 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.
- Granite feels noticeably heavier for its size (specific gravity 2.7 versus 0.25–0.9 for Pumice).
- Hold a thin edge to the light: Granite is opaque, Pumice is Opaque, translucent in thin shards.
- They overlap in gray and white, but Granite also comes in pink and black and Pumice also comes in brown and yellow.
Granite vs Pumice properties
| Property | Granite | Pumice |
|---|---|---|
| Type | Igneous Rocks | Igneous Rocks |
| Mohs hardness | 6.5 | 5–6 |
| Luster | vitreous | Dull to glassy |
| Streak | Variable; test individual minerals | — |
| Transparency | opaque | Opaque, translucent in thin shards |
| Specific gravity | 2.7 | 0.25–0.9 |
| Crystal system | varies | Amorphous |
| Common colors | Pink, Gray, White, Black | White, Light gray, Tan, Pale yellow |
| Rarity | common | common |
| Typical specimen value | $1–$50+ | $1–$75+ |
Which is more valuable?
Typical specimens of Granite and Pumice trade in a similar range, around $10.
About Granite
Granite is a coarse-grained igneous rock composed mainly of quartz, feldspar, and mica. It's one of the most common rocks in Earth's continental crust.
About Pumice
Pumice is a light-colored, extrusive volcanic rock so full of trapped gas bubbles, or vesicles, that it can float on water. It forms when gas-rich, silica-rich magma is violently depressurized during an explosive eruption, freezing the expanding bubbles in place as volcanic glass. Its extremely low density and rough, abrasive texture have made it useful to people for thousands of years.
Granite vs Pumice FAQ
Is Granite the same as Pumice?
No. Both are igneous rocks, but they are distinct rock types with different hardness, streak or luster. Granite is harder (Mohs 6.5) than Pumice (Mohs 5–6), so Granite will scratch Pumice 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 Granite from Pumice?
Granite is harder (Mohs 6.5) than Pumice (Mohs 5–6), so Granite will scratch Pumice 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. Granite feels noticeably heavier for its size (specific gravity 2.7 versus 0.25–0.9 for Pumice). Hold a thin edge to the light: Granite is opaque, Pumice is Opaque, translucent in thin shards.
Which is harder, Granite or Pumice?
Granite is harder: Mohs 6.5 against Mohs 5–6 for Pumice.
Which is more valuable, Granite or Pumice?
Typical specimens of Granite and Pumice trade in a similar range, around $10.
