RocksdayPumice vs Scoria
How to tell them apart
Volcanic glass so full of gas bubbles that it floats on water. It forms in explosive, gas-rich eruptions.
Photo: User MPF on en.wikipedia, CC BY-SA 3.0
Dark, bubble-filled lava that piles up as cinder cones. Larger holes and heavier than pumice.
Photo: ScoriaPumice, CC0
Quick tests
- Heft: Scoria feels noticeably heavier for its size (specific gravity 1–2 vs 0.25–0.9).
Key differences
- Scoria is dark, heavier and sinks.
- Pumice is pale, finer-bubbled and floats.
Side by side
| Property | Pumice | Scoria |
|---|---|---|
| Type | Igneous rock | Igneous rock |
| Mohs hardness | 5.5–6 | 5.5–6 |
| Luster | Dull to silky | Dull |
| Colors | White, Gray | Black, Red, Brown |
| Crystal system / structure | Vesicular (frothy) | Vesicular (bubbly) |
| Specific gravity | 0.25–0.9 | 1–2 |
| Found in | Lipari, Italy; Santorini, Greece | Sunset Crater, Arizona; Mauna Kea, Hawaii |
Properties that are the same for both are grayed out.
How to identify pumice
- Very light — it floats.
- Pale gray or white.
- Full of tiny bubbles and stretched fibers.
- Feels rough and scratchy.
Structure: Vesicular (frothy)
Full Pumice guide →How to identify scoria
- Black to rusty red.
- Full of large, rounded holes.
- Light for its size but sinks in water.
- Rough, crunchy texture.
Structure: Vesicular (bubbly)
Full Scoria guide →More comparisons
Could you tell them apart from a blurry close-up?
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