igneous
Weathered vesicular volcanic rock, likely pumiceous andesite or rhyolite
Pumiceous intermediate-to-felsic volcanic rock; commonly composed of plagioclase, quartz, alkali feldspar, and volcanic glass, with possible iron-oxide staining
AI-generated identification · may be incorrectLight tan to pink-brown, highly porous and irregular, with dull to earthy luster and dark mineral or weathering spots. Hardness is approximately 5–6 for the crystalline portions; no obvious cleavage, and low to moderate density depending on vesicle content.
Identified More igneous →
Explore Weathered vesicular volcanic rock, likely pumiceous andesite or rhyolite in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Light tan to pink-brown, highly porous and irregular, with dull to earthy luster and dark mineral or weathering spots. Hardness is approximately 5–6 for the crystalline portions; no obvious cleavage, and low to moderate density depending on vesicle content.
Formation & geological history
Formed when gas-rich lava or ash cooled rapidly during an explosive volcanic eruption, trapping bubbles in glassy rock. Its exact geological age cannot be determined from the image; similar material occurs in volcanic fields of many ages.
Uses & applications
Usually collected as a natural specimen; pumice is used as an abrasive, lightweight aggregate, and horticultural medium, while denser volcanic rock may be used locally as construction aggregate.
Geological facts
The cavities are vesicles created by escaping volcanic gases; dark patches may be magnetite, mafic minerals, or secondary manganese/iron oxides.
Field identification & locations
Check whether it is unusually light, porous, and possibly floats; a glassy fracture and lack of visible sedimentary layering support pumice. Common in volcanic regions worldwide, including Italy, Iceland, Mexico, and the western United States.
