igneous
Vesicular volcanic rock, likely pumice or weathered scoria
Pumice/scoria; predominantly volcanic glass and plagioclase, with possible pyroxene or iron oxides
AI-generated identification · may be incorrectLight gray to brown, highly vesicular, rough and dull to subvitreous; hardness about 5–6, generally no cleavage, and low specific gravity. The cavities formed from trapped volcanic gas; the dense, layered appearance may indicate scoria or altered pumice.
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Physical properties
Light gray to brown, highly vesicular, rough and dull to subvitreous; hardness about 5–6, generally no cleavage, and low specific gravity. The cavities formed from trapped volcanic gas; the dense, layered appearance may indicate scoria or altered pumice.
Formation & geological history
An extrusive igneous rock formed when gas-rich magma rapidly erupted and quenched, typically during the Quaternary or older volcanic activity. Weathering and mineral deposition have enlarged or partially filled the vesicles.
Uses & applications
Pumice is used as an abrasive, lightweight aggregate, concrete additive, horticultural medium, and exfoliant; scoria is used in landscaping and construction fill. This irregular specimen has modest collector value.
Geological facts
Its abundant holes are vesicles, not fossils, and pumice can sometimes float if its bulk density is below water. The specimen’s rounded form and altered surface may reflect transport or prolonged weathering.
Field identification & locations
Common around volcanic fields, especially basaltic and rhyolitic lava deposits; identify by glassy texture, abundant gas cavities, and lack of sedimentary layering or fossil structure. A streak, density, and thin-section test would distinguish pumice from scoria more reliably.
