igneous
Pumice
Pumice (Amorphous silicate glass with trapped gas bubbles)
AI-generated identification · may be incorrectHardness: 5-6 on Mohs scale (brittle); Color: Light grey, tan, cream, or off-white; Luster: Dull to pearly; Texture: Highly vesicular (filled with small cavities/vesicles); Density: Extremely low specific gravity (often floats on water).
- Hardness
- 5-6 on Mohs scale (brittle)
- Color
- Light grey, tan, cream, or off-white
- Luster
- Dull to pearly
Identified More igneous →
Explore Pumice in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 5-6 on Mohs scale (brittle); Color: Light grey, tan, cream, or off-white; Luster: Dull to pearly; Texture: Highly vesicular (filled with small cavities/vesicles); Density: Extremely low specific gravity (often floats on water).
Formation & geological history
Formed during explosive volcanic eruptions when highly gas-saturated, felsic (silica-rich) lava rapidly cools and depressurizes, trapping millions of tiny gas bubbles inside a glass matrix.
Uses & applications
Used widely in cosmetic exfoliation (pumice stones), lightweight concrete production, abrasive cleaners, horticulture (soil aeration), and stonewashing denim jeans.
Geological facts
Pumice is one of the few rocks that can float on water due to its high porosity and closed-cell vesicle structure. Giant floating 'pumice rafts' created by underwater volcanic eruptions can travel thousands of miles across oceans.
Field identification & locations
Identified in the field by its sponge-like vesicular texture, pale color, and remarkably light weight. Commonly found near active or historic explosive volcanic regions such as Italy, Greece, the US Pacific Northwest, and New Zealand.
