igneous
Vesicular volcanic rock, likely pumice or scoria
Highly vesicular basaltic-to-rhyolitic volcanic rock; exact identification requires density, color, and composition tests
AI-generated identification · may be incorrectVery porous, light tan-gray, dull to slightly glassy; hardness about 5–6 Mohs, with irregular cavities (vesicles) and no obvious cleavage. Pumice is usually lightweight and silica-rich; scoria is darker, denser, and basaltic.
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Physical properties
Very porous, light tan-gray, dull to slightly glassy; hardness about 5–6 Mohs, with irregular cavities (vesicles) and no obvious cleavage. Pumice is usually lightweight and silica-rich; scoria is darker, denser, and basaltic.
Formation & geological history
Forms when gas-rich lava rapidly cools, trapping bubbles; typically Quaternary to recent volcanic material. The image’s pale color and exceptionally fine pores favor pumice, though weathered scoria is possible.
Uses & applications
Used as an abrasive, lightweight aggregate, horticultural soil additive, filtration medium, and concrete aggregate; attractive pieces are sold as decorative specimens.
Geological facts
Vesicles record dissolved volcanic gases escaping during eruption. Pumice can float temporarily if its pores remain connected; scoria generally sinks.
Field identification & locations
Common around explosive or highly gas-rich volcanoes, including Italy, Iceland, Greece, Turkey, the western United States, and New Zealand. Check whether it floats and compare density: pumice is usually below 1 g/cm³.
