igneous
Vesicular volcanic rock, likely pumice or scoria
Pumice (highly vesicular rhyolitic–dacitic volcanic glass) or scoria (vesicular basaltic rock)
AI-generated identification · may be incorrectLight gray, porous, and rough with abundant gas cavities; likely glassy to fine-grained, with hardness about 5–6 and low specific gravity. Its pale color favors pumice, while scoria is usually darker and denser.
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Physical properties
Light gray, porous, and rough with abundant gas cavities; likely glassy to fine-grained, with hardness about 5–6 and low specific gravity. Its pale color favors pumice, while scoria is usually darker and denser.
Formation & geological history
Forms when gas-rich lava rapidly decompresses and cools during an explosive eruption, preserving bubbles; age depends on the volcanic deposit. Common in young volcanic terrains and pyroclastic deposits.
Uses & applications
Used as a lightweight abrasive, concrete and masonry aggregate, horticultural soil additive, filtration media, and exfoliating stone. Attractive pieces may be sold as educational or collector specimens.
Geological facts
Pumice can float if its connected pores are not waterlogged; scoria generally sinks. The specimen’s irregular holes are vesicles, not fossils or weathering pits.
Field identification & locations
Look for a very low-density, frothy texture and sharp glassy surfaces; pale gray indicates pumice, whereas dark red-black indicates scoria. Common sources include Iceland, Italy, Greece, Mexico, the western United States, and New Zealand.
