igneous
Pumice
Pumice (Felsic volcanic glass)
AI-generated identification · may be incorrectHardness 5-6 (Mohs), highly vesicular with a frothy texture, dull to vitreous luster, amorphous structure, very low specific gravity (often floats on water).
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Physical properties
Hardness 5-6 (Mohs), highly vesicular with a frothy texture, dull to vitreous luster, amorphous structure, very low specific gravity (often floats on water).
Formation & geological history
Formed during explosive volcanic eruptions when high-silica, gas-rich lava rapidly depressurizes and cools, trapping expanding gas bubbles.
Uses & applications
Widely used as an abrasive in beauty products and stonewashed denim, as lightweight concrete aggregate, and as a soil aerator in horticulture.
Geological facts
Pumice is one of the only rocks that can float on water, sometimes forming massive floating 'rafts' on the ocean that can drift for thousands of miles.
Field identification & locations
Identify by its exceptionally light weight, pale gray-to-white color, and sponge-like vesicular texture. Commonly found near active or historic explosive volcanic zones.
