igneous
Pumice
Pumice
Hardness: 6 (on dry glass, but very fragile), Color: Whitish to grey or yellowish, Luster: Earthy to silky, Crystal structure: Amorphous (volcanic glass), Cleavage: None, Specific gravity: Less than 1.0 (floats on water).
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Physical properties
Hardness: 6 (on dry glass, but very fragile), Color: Whitish to grey or yellowish, Luster: Earthy to silky, Crystal structure: Amorphous (volcanic glass), Cleavage: None, Specific gravity: Less than 1.0 (floats on water).
Formation & geological history
Formed from explosive volcanic eruptions where gas-rich felsic to intermediate lava rapidly cools and depressurizes, creating a frothy glass foam.
Uses & applications
Used in lightweight aggregate, abrasive stones, pumice stones for personal care, and concrete manufacturing.
Geological facts
Pumice is one of the only rocks that can float on water due to its high concentration of trapped gas bubbles.
Field identification & locations
Found worldwide near active or recent volcanic regions, especially in areas with rhyolitic or dacitic volcanism.
