igneous
Vesicular volcanic rock, likely scoria
Scoria (mafic volcanic vesicular basalt), chiefly plagioclase, pyroxene, olivine, and volcanic glass
AI-generated identification · may be incorrectDark tan-brown, highly porous, dull to weakly vitreous; hardness about 5–6 Mohs, no obvious cleavage, and low-to-moderate density. The rounded cavities are vesicles formed by trapped gas bubbles; surface weathering may produce the ochre color.
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Physical properties
Dark tan-brown, highly porous, dull to weakly vitreous; hardness about 5–6 Mohs, no obvious cleavage, and low-to-moderate density. The rounded cavities are vesicles formed by trapped gas bubbles; surface weathering may produce the ochre color.
Formation & geological history
Forms when gas-rich basaltic lava or frothy volcanic ejecta rapidly cools, commonly during cinder-cone eruptions; most examples are Cenozoic or younger, though scoria occurs throughout geologic time.
Uses & applications
Used as lightweight aggregate, landscaping stone, abrasive, and soil-aeration material; attractive pieces may be collected, but it is generally not a gemstone.
Geological facts
The specimen is consistent with scoria, although strongly weathered pumice or vesicular basalt is also possible from an image alone. Scoria is typically denser and darker than pumice because it contains more iron- and magnesium-rich melt.
Field identification & locations
Identify it by abundant irregular vesicles, rough texture, and volcanic appearance; common localities include Hawaii, Iceland, Mexico, Italy, and volcanic fields worldwide. A fresh broken surface and a streak, density, or petrographic test would improve identification.
