igneous
Pumice
Pumice (Highly vesicular felsic volcanic rock)
Porous and vesicular texture, Hardness: 5-6 (Mohs scale), Color: Creamy white to light gray, Luster: Dull to pearly, Density: Low enough to float on water (Specific Gravity < 1.0)
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Physical properties
Porous and vesicular texture, Hardness: 5-6 (Mohs scale), Color: Creamy white to light gray, Luster: Dull to pearly, Density: Low enough to float on water (Specific Gravity < 1.0)
Formation & geological history
Formed during explosive volcanic eruptions where gas-rich lava cools rapidly, trapping bubbles in a glassy matrix. Most deposits range from the Quaternary period to the present.
Uses & applications
Used as an abrasive in cleaning products, cosmetic exfoliants, lightweight concrete aggregate, and in stone-washing textiles (jeans).
Geological facts
Pumice is the only rock known to float on water until it eventually becomes waterlogged and sinks. Large rafts of pumice can float across oceans for thousands of miles after an eruption.
Field identification & locations
Identify in the field by its extreme lightness (low density) and frothy, bubble-filled appearance. Found in volcanic regions like the Mediterranean, Iceland, and the western United States.
