igneous
Pumice
Pumice, vesicular volcanic glass; typically silica-rich, with composition similar to rhyolite
AI-generated identification · may be incorrectPale cream to light gray, dull or silky luster, and highly porous, frothy texture. Hardness is variable (about 5–6 Mohs for glassy material); crystal structure is mostly amorphous, with sparse microscopic crystals possible.
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Physical properties
Pale cream to light gray, dull or silky luster, and highly porous, frothy texture. Hardness is variable (about 5–6 Mohs for glassy material); crystal structure is mostly amorphous, with sparse microscopic crystals possible.
Formation & geological history
Forms when gas-rich, silica-rich magma erupts and cools rapidly, trapping abundant bubbles in volcanic glass. It may be geologically very young or much older, depending on the eruption.
Uses & applications
Used as a lightweight aggregate, abrasive, soil conditioner, and exfoliating stone; attractive or unusually textured pieces are collected.
Geological facts
Pumice can be so vesicular that it floats temporarily, though this small specimen’s buoyancy cannot be determined from the image.
Field identification & locations
The light color and dense, irregular cavities suggest pumice, but the photo does not show enough detail to confirm it. Common around explosive volcanoes and volcanic deposits worldwide; check that the cavities are natural and the piece feels unusually light.
