igneous
Weathered vesicular volcanic rock (likely scoria/tuff)
Basaltic scoria or vesicular volcanic tuff; exact identification is limited by the photograph
AI-generated identification · may be incorrectDark brown-gray, highly porous, rough and dull with abundant cavities and weathering rinds; likely hardness about 5–6 Mohs, with no visible cleavage. The rounded, pitted texture suggests vesicles or weathered pumice-like volcanic material.
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Physical properties
Dark brown-gray, highly porous, rough and dull with abundant cavities and weathering rinds; likely hardness about 5–6 Mohs, with no visible cleavage. The rounded, pitted texture suggests vesicles or weathered pumice-like volcanic material.
Formation & geological history
Formed when gas-rich lava or volcanic ash cooled rapidly, trapping bubbles; weathering has enlarged or stained the pores. Such rocks are generally Cenozoic to recent, though similar textures occur in older volcanic provinces.
Uses & applications
Used as lightweight aggregate, landscaping stone, drainage material, abrasives, and occasionally decorative specimens; usually little jewelry value.
Geological facts
Scoria is typically heavier and darker than pumice because it contains more iron-rich basaltic minerals. The specimen may also be vesicular basalt or welded tuff, which cannot be distinguished confidently without density, streak, and close texture examination.
Field identification & locations
Common in volcanic regions, including Hawaii, Iceland, the western United States, Italy, and Japan. Look for vesicles, iron staining, low density, and a lack of sedimentary layering; a glassy surface and very low density favor pumice.
