igneous
Pumiceous volcanic rock (likely rhyolitic pumice/tuff)
Felsic volcanic glass and ash; commonly quartz–alkali feldspar–plagioclase composition
AI-generated identification · may be incorrectLight gray to pink-brown, fine-grained and highly vesicular, with scattered dark mafic inclusions; dull to faintly silky luster. Hardness about 5–6, low density, and no obvious cleavage; the rounded surface appears naturally weathered or tumbled.
Identified More igneous →
Explore Pumiceous volcanic rock (likely rhyolitic pumice/tuff) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Light gray to pink-brown, fine-grained and highly vesicular, with scattered dark mafic inclusions; dull to faintly silky luster. Hardness about 5–6, low density, and no obvious cleavage; the rounded surface appears naturally weathered or tumbled.
Formation & geological history
Formed when gas-rich, silica-rich magma erupted explosively and rapidly quenched, trapping bubbles; likely Cenozoic or younger, though age cannot be determined from the image. Common in volcanic ash-flow deposits, pumice layers, and welded or reworked tuffs.
Uses & applications
Used as lightweight abrasive, horticultural medium, concrete aggregate, and decorative stone; attractive pieces may be collected but are generally low value.
Geological facts
The pink coloration commonly reflects oxidized iron, while dark spots may be lithic fragments or mafic minerals. Its vesicles distinguish it from ordinary dense granite or sandstone.
Field identification & locations
Identify by unusually low weight, abundant holes, glassy/fine texture, and lack of visible sedimentary layering; common in volcanic regions such as the western United States, Italy, Iceland, Japan, and New Zealand.
