igneous
Pumice
Pumice
Hardness: 6 on the Mohs scale, Color: Light gray, white, yellowish, or brownish, Luster: Dull to earthy, Crystal structure: Amorphous (volcanic glass with vesicular texture), Specific gravity: Less than 1.0 (floats on water)
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Physical properties
Hardness: 6 on the Mohs scale, Color: Light gray, white, yellowish, or brownish, Luster: Dull to earthy, Crystal structure: Amorphous (volcanic glass with vesicular texture), Specific gravity: Less than 1.0 (floats on water)
Formation & geological history
Formed from explosive volcanic eruptions where gas-rich, felsic (silica-rich) lava rapidly cools and depressurizes, trapping gas bubbles within the glass matrix.
Uses & applications
Used in lightweight concrete, abrasive soaps, cosmetic exfoliants, horticulture for soil aeration, and stonewashed denim production.
Geological facts
Pumice is one of the only rocks that can float on water due to its high porosity and trapped air bubbles.
Field identification & locations
Easily identified by its extremely lightweight nature, vesicular (frothy with holes) texture, and pale color. Found globally near active or historical volcanic regions.
