igneous
Pumice
Pumice; highly vesicular volcanic glass, commonly rhyolitic to dacitic in composition
AI-generated identification · may be incorrectVery lightweight, pale pink-tan, frothy and porous with a dull to silky luster; hardness about 5–6 Mohs, no cleavage, amorphous glassy structure, and typically low specific gravity (often floats).
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Physical properties
Very lightweight, pale pink-tan, frothy and porous with a dull to silky luster; hardness about 5–6 Mohs, no cleavage, amorphous glassy structure, and typically low specific gravity (often floats).
Formation & geological history
Forms when gas-rich felsic lava erupts explosively and rapidly cools, trapping abundant bubbles; specimens are generally geologically young, from Cenozoic to recent volcanic eruptions.
Uses & applications
Used as an abrasive, exfoliant, lightweight aggregate, soil additive, filtration medium, and decorative stone; usually low jewelry value.
Geological facts
Its holes are vesicles formed by expanding volcanic gases, and pumice can be transported long distances by water because it may float.
Field identification & locations
Identify it by its unusually low density, abundant interconnected pores, rough texture, and ability to scratch softer materials; common sources include Italy, Greece, Turkey, Iceland, the western United States, and New Zealand.
