igneous
Porous volcanic rock (likely pumice)
Pumice; vesicular volcanic glass, typically silica-rich
AI-generated identification · may be incorrectPale tan-gray, rough and highly porous with a dull to slightly glassy luster; hardness and density vary, commonly Mohs 5–6 and low specific gravity. The cavities are gas bubbles; no distinct cleavage or visible crystal structure.
Identified More igneous →
Explore Porous volcanic rock (likely pumice) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Pale tan-gray, rough and highly porous with a dull to slightly glassy luster; hardness and density vary, commonly Mohs 5–6 and low specific gravity. The cavities are gas bubbles; no distinct cleavage or visible crystal structure.
Formation & geological history
Forms when gas-rich lava cools rapidly during explosive eruptions, trapping bubbles in volcanic glass. Its age cannot be determined from the image.
Uses & applications
Used as an abrasive, lightweight aggregate, and horticultural soil amendment; small pieces are also collected or used for personal exfoliation.
Geological facts
Pumice can be so vesicular that it floats, though this specimen’s buoyancy cannot be established visually.
Field identification & locations
Look for abundant rounded or stretched cavities and unusually low weight; common around volcanoes and in volcanic deposits worldwide. The image is consistent with pumice, but lighting and scale limit certainty.
