igneous
Dark vesicular volcanic rock, likely scoria
Scoria; iron-rich basaltic to andesitic pyroclast
AI-generated identification · may be incorrectTypically dark brown to black, highly vesicular, dull to slightly glassy, with fine-grained volcanic groundmass; hardness about 5–6, no consistent cleavage, and specific gravity commonly 2.0–2.8. The image is dim, so identification is approximate; it could also be vesicular basalt.
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Physical properties
Typically dark brown to black, highly vesicular, dull to slightly glassy, with fine-grained volcanic groundmass; hardness about 5–6, no consistent cleavage, and specific gravity commonly 2.0–2.8. The image is dim, so identification is approximate; it could also be vesicular basalt.
Formation & geological history
Forms when gas-rich basaltic or andesitic lava cools rapidly, trapping bubbles; commonly produced in cinder cones and lava flows during Quaternary to modern volcanism. It occurs in volcanic fields worldwide.
Uses & applications
Used as lightweight aggregate, drainage and landscaping stone, abrasive material, and occasionally in decorative specimens; generally not a jewelry gemstone.
Geological facts
Scoria is denser and darker than pumice because its magma is more iron- and magnesium-rich. Its abundant holes record escaping volcanic gases during eruption.
Field identification & locations
Identify it by its black or reddish-brown color, rough bubbly texture, and greater weight than pumice; a streak, density test, and fresh broken surface help distinguish it from slag. Common locations include Hawaii, Iceland, Italy, Mexico, and western North America.
