igneous
Pumice
Vesicular volcanic glass
Hardness: 5-6 (Mohs scale), Color: light gray to cream, Luster: dull to silky, Crystal Structure: amorphous (glassy), highly vesicular (filled with air bubbles), very low specific gravity (often floats on water).
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Physical properties
Hardness: 5-6 (Mohs scale), Color: light gray to cream, Luster: dull to silky, Crystal Structure: amorphous (glassy), highly vesicular (filled with air bubbles), very low specific gravity (often floats on water).
Formation & geological history
Formed during explosive volcanic eruptions when highly pressurized, gas-rich magma is ejected into the air, cooling rapidly and trapping gas bubbles as it solidifies. Primarily found in volcanic regions of various ages.
Uses & applications
Used as an abrasive in cleaning products, skin exfoliants (pumice stones), lightweight aggregate in concrete/cinder blocks, and in stonewashed denim production.
Geological facts
Pumice is the only rock that can reliably float on water for long periods. Large eruptions can create 'pumice rafts' that drift across oceans for thousands of miles.
Field identification & locations
Identify by its extremely lightweight feel and sponge-like texture with visible holes (vesicles). Found in volcanic fields, beaches near volcanic islands, or as decorative landscaping stones.
