igneous
Pumice
Pumice (Vesicular Rhyolite)
Hardness: 5-6 Mohs (though fragile), Color: light grey to cream, Luster: dull to pearly, Structure: highly vesicular/porous, very low specific gravity (floats in water).
Identified More igneous →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 5-6 Mohs (though fragile), Color: light grey to cream, Luster: dull to pearly, Structure: highly vesicular/porous, very low specific gravity (floats in water).
Formation & geological history
Formed during explosive volcanic eruptions when extremely hot, gas-rich magma is violently ejected into the air, cooling rapidly and trapping gas bubbles as it solidifies.
Uses & applications
Used as an abrasive in cosmetics (exfoliants), polishing compounds, stonewashed jeans, lightweight concrete aggregate, and horticultural soil drainage.
Geological facts
Pumice is the only rock that can float on water due to its air-filled pores. Large eruptions can create 'pumice rafts' that float across oceans for thousands of miles.
Field identification & locations
Identify by its extreme lightness and sponge-like appearance. Commonly found in volcanic arc regions and recent volcanic deposits. Collectors look for color variations and unbroken vesicles.
