igneous
Pumice
Felsic volcanic glass
AI-generated identification · may be incorrectHardness 6 on Mohs scale, pale gray to cream color, dull luster, highly vesicular amorphous structure, low specific gravity allowing it to float on water.
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Physical properties
Hardness 6 on Mohs scale, pale gray to cream color, dull luster, highly vesicular amorphous structure, low specific gravity allowing it to float on water.
Formation & geological history
Formed from rapidly cooling, gas-rich felsic lava during explosive volcanic eruptions, common in Pacific Northwest volcanic arcs.
Uses & applications
Used in lightweight concrete, abrasive soaps, horticulture as a soil conditioner, and personal care pumice stones.
Geological facts
Pumice is one of the only rocks that can float on water due to its trapped gas bubbles forming a foam-like glass matrix.
Field identification & locations
Easily identified by its extremely low weight and abundance of tiny air cavities; commonly found near regional volcanic deposits.
