igneous
Pumice
Pumice (volcanic glass foam)
AI-generated identification · may be incorrectHardness 5.5 to 6, extremely lightweight, vesicular texture with numerous gas cavities, dull luster, light gray to tan color, amorphous crystal structure with specific gravity under 1.0.
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Physical properties
Hardness 5.5 to 6, extremely lightweight, vesicular texture with numerous gas cavities, dull luster, light gray to tan color, amorphous crystal structure with specific gravity under 1.0.
Formation & geological history
Formed from the rapid cooling of gas-rich felsic or intermediate lava during explosive volcanic eruptions, preventing crystal growth.
Uses & applications
Used in lightweight concrete, concrete aggregates, abrasive blocks, cosmetics, and horticultural soil conditioning.
Geological facts
Pumice is the only known rock that can float on water due to its high volume of trapped air bubbles.
Field identification & locations
Identified easily by its extremely low weight and sponge-like vesicular texture; commonly found near active or historical volcanic regions worldwide.
