igneous
Pumice
Pumice (a highly vesicular volcanic glass)
Hardness: 5-6 Mohs. Color: White, light gray, or cream. Luster: Dull to pearly. Structure: Highly vesicular/porous (frothy glass). Specific Gravity: 0.25 to 1.2, often floats on water.
- Hardness
- 5-6 Mohs
- Color
- White, light gray, or cream
- Luster
- Dull to pearly
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Physical properties
Hardness: 5-6 Mohs. Color: White, light gray, or cream. Luster: Dull to pearly. Structure: Highly vesicular/porous (frothy glass). Specific Gravity: 0.25 to 1.2, often floats on water.
Formation & geological history
Formed during explosive volcanic eruptions when lava with high water and gas content is ejected into the air; rapid cooling traps gas bubbles. Found in young volcanic regions.
Uses & applications
Used as an abrasive in soaps (pumice stones), cosmetic exfoliants, stone-washed denim production, lightweight concrete aggregate, and horticulture (perlite alternative).
Geological facts
Pumice is the only rock that can float on water due to its incredible porosity. Massive 'pumice rafts' can travel across oceans for years after an eruption.
Field identification & locations
Identify by its light weight, rough texture, and ability to float. Commonly found in volcanic areas like the Cascades (USA), Italy, or New Zealand.
