igneous
Vesicular volcanic rock, likely pumice or scoriaceous rhyolite
Pumice/scoria; predominantly silicate glass with quartz–feldspar minerals
AI-generated identification · may be incorrectLight tan, highly vesicular, rough and porous, with a dull to slightly glassy luster; typically hardness 5–6, no consistent cleavage, and low specific gravity. The pale color favors pumice or frothy rhyolite over dark basaltic scoria.
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Physical properties
Light tan, highly vesicular, rough and porous, with a dull to slightly glassy luster; typically hardness 5–6, no consistent cleavage, and low specific gravity. The pale color favors pumice or frothy rhyolite over dark basaltic scoria.
Formation & geological history
Formed when gas-rich felsic lava erupted explosively and rapidly quenched, trapping bubbles in volcanic glass; commonly Quaternary to recent, though older deposits also occur. Exact identification requires density, streak, and petrographic or chemical testing.
Uses & applications
Used as lightweight aggregate, abrasive, exfoliating stone, horticultural medium, and cement additive; attractive pieces may be collected but are rarely jewelry grade.
Geological facts
Pumice can float until its pores fill with water, whereas denser scoria usually sinks. The specimen’s irregular cavities and pale matrix are consistent with an oxidized or weathered felsic pyroclast.
Field identification & locations
Identify by extreme porosity, low weight, sharp vesicles, and glassy texture; common around explosive volcanic fields worldwide, including Italy, Iceland, Turkey, the western United States, and New Zealand.
