igneous
Weathered, vesicular volcanic rock (likely basaltic scoria)
Scoria, probably basaltic; exact identification requires testing
AI-generated identification · may be incorrectDark gray to brown, highly irregular and vesicular with a dull to slightly glassy luster; chiefly fine-grained plagioclase, pyroxene, and iron-rich volcanic glass. Typical hardness is about 5–6 Mohs and specific gravity about 2.0–2.8, though the pale coating and rounded inclusions obscure the texture.
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Physical properties
Dark gray to brown, highly irregular and vesicular with a dull to slightly glassy luster; chiefly fine-grained plagioclase, pyroxene, and iron-rich volcanic glass. Typical hardness is about 5–6 Mohs and specific gravity about 2.0–2.8, though the pale coating and rounded inclusions obscure the texture.
Formation & geological history
Forms when gas-rich mafic lava cools rapidly at or near a volcanic vent, commonly during the Quaternary and younger volcanic activity. The specimen appears heavily weathered or coated, possibly with secondary minerals or soil cement.
Uses & applications
Used as lightweight aggregate, landscaping stone, abrasive, and sometimes in construction blocks; generally little jewelry value.
Geological facts
Scoria is more vesicular and usually darker than dense basalt; pale patches may be weathering products, ash, or adhering sediment rather than the original rock.
Field identification & locations
Look for abundant trapped-gas holes, low density, a rough surface, and no obvious sedimentary layering; a streak, magnet test, density measurement, and fresh break would improve identification. Common around volcanic fields, cinder cones, and lava flows worldwide.
