igneous
Vesicular volcanic rock, likely pumice or scoria
Pumice/scoria; predominantly volcanic glass with feldspar, pyroxene, and possibly olivine
AI-generated identification · may be incorrectLight tan to brown, highly vesicular, rough and dull to slightly glassy; hardness about 5–6 Mohs, with no obvious cleavage. Pumice is usually very lightweight and may float; scoria is darker, denser, and commonly iron-rich.
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Physical properties
Light tan to brown, highly vesicular, rough and dull to slightly glassy; hardness about 5–6 Mohs, with no obvious cleavage. Pumice is usually very lightweight and may float; scoria is darker, denser, and commonly iron-rich.
Formation & geological history
Forms when gas-rich lava rapidly cools during an explosive eruption, trapping bubbles in the solidifying melt. Most examples are geologically young, ranging from modern volcanic deposits to Quaternary material.
Uses & applications
Used as an abrasive, lightweight aggregate, horticultural soil additive, and landscaping stone; attractive pieces are sold as curios or specimens.
Geological facts
The open cavities are gas bubbles rather than fossils. The specimen’s tan-brown color and coarse, irregular pores suggest scoria or an oxidized pumice, but a photo cannot distinguish them confidently.
Field identification & locations
Common around volcanic regions, including the western United States, Mexico, Iceland, Italy, and New Zealand. Check whether it floats, its density, and whether the surface has sharp glassy edges; avoid confusing it with porous concrete or slag.
