igneous
Red vesicular volcanic rock, likely scoria
Scoria (vesicular basalt/andesite), composed mainly of plagioclase, pyroxene, and iron-rich glass
AI-generated identification · may be incorrectDark red-orange, porous, and dull to slightly glassy; typically hardness 5–6, no visible cleavage, fine-grained volcanic texture, and specific gravity about 2.0–2.5. The cavities are gas bubbles, with iron oxidation producing the red color.
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Physical properties
Dark red-orange, porous, and dull to slightly glassy; typically hardness 5–6, no visible cleavage, fine-grained volcanic texture, and specific gravity about 2.0–2.5. The cavities are gas bubbles, with iron oxidation producing the red color.
Formation & geological history
Forms when gas-rich mafic to intermediate lava rapidly cools at or near the surface, commonly during cinder-cone eruptions; specimens may range from modern to millions of years old.
Uses & applications
Used as lightweight aggregate, drainage material, landscaping stone, abrasive, and occasionally in decorative or lapidary pieces; generally unsuitable for fine jewelry.
Geological facts
Scoria is typically denser and darker than pumice because it contains more iron and less total vesicularity. The pictured piece may also be a tumbled or weathered fragment of red volcanic rock.
Field identification & locations
Identify it by abundant irregular holes, low density, rough texture, and red-brown coloration; common in volcanic regions such as Hawaii, Arizona, New Mexico, Iceland, Italy, and Japan.
