igneous
Pumice
Pumice, vesicular volcanic glass, commonly rhyolitic to dacitic in composition
AI-generated identification · may be incorrectLight gray, highly vesicular, dull to slightly glassy; typically Mohs 5–6, with no distinct cleavage and irregular fracture. The rounded shape may result from weathering or handling.
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Physical properties
Light gray, highly vesicular, dull to slightly glassy; typically Mohs 5–6, with no distinct cleavage and irregular fracture. The rounded shape may result from weathering or handling.
Formation & geological history
Forms when gas-rich, silica-rich lava rapidly cools and traps bubbles during explosive eruptions; it can be geologically recent or much older. The image alone cannot establish its age or exact composition.
Uses & applications
Used as an abrasive, lightweight aggregate, soil amendment, and in polishing and personal-care products; attractive pieces are collected.
Geological facts
Pumice is so porous that many pieces float initially, though they eventually become waterlogged.
Field identification & locations
Identify it by its abundant cavities and unusually low density; common deposits occur near volcanoes, including in Italy, Iceland, Turkey, and the western United States. Similar-looking vesicular rocks can be denser scoria.
