igneous
Pumice
Pumice (volcanic glass foam)
AI-generated identification · may be incorrectHardness of 5.5 to 6 on the Mohs scale, typically light gray to white or yellowish, vitreous to dull luster, amorphous volcanic glass structure with no cleavage, extremely low specific gravity allowing it to float on water.
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Physical properties
Hardness of 5.5 to 6 on the Mohs scale, typically light gray to white or yellowish, vitreous to dull luster, amorphous volcanic glass structure with no cleavage, extremely low specific gravity allowing it to float on water.
Formation & geological history
Formed through the explosive eruption of silica-rich magma where trapped gases rapidly expand, causing the lava to foam and instantly solidify into glass before crystals can form.
Uses & applications
Widely used as an abrasive in personal care products, stonewashing jeans, lightweight aggregate in construction, and as a soil amendment in horticulture.
Geological facts
Pumice is the only rock that can float on water due to its high porosity filled with trapped gas bubbles.
Field identification & locations
Easily identified by its very light weight, pale color, and abundant visible gas cavities (vesicles). Found globally near active or historical volcanic regions.
