igneous
Scoria (vesicular basalt)
Vesicular basalt; primarily plagioclase, pyroxene, olivine, and volcanic glass
AI-generated identification · may be incorrectDark reddish-brown, highly vesicular, rough, and typically dull to subvitreous; hardness about 5–6 Mohs, with no prominent cleavage and low-to-moderate density due to abundant gas cavities.
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Physical properties
Dark reddish-brown, highly vesicular, rough, and typically dull to subvitreous; hardness about 5–6 Mohs, with no prominent cleavage and low-to-moderate density due to abundant gas cavities.
Formation & geological history
An extrusive volcanic rock formed when basaltic lava cooled rapidly while trapped gases expanded; commonly Quaternary to modern in age and associated with cinder cones, lava flows, and volcanic fields.
Uses & applications
Used as lightweight aggregate, drainage and landscaping stone, abrasive material, and sometimes in barbecue or fire pits; generally low collector value.
Geological facts
Its red-brown color commonly results from oxidation of iron-bearing minerals during or after eruption. Scoria is denser and darker than pumice, which is usually pale and may float.
Field identification & locations
Identify it by its dark color, abundant irregular holes, and heavy feel relative to pumice; common sources include Hawaii, Iceland, Mexico, Italy, and volcanic regions worldwide. The pictured specimen could also be vesicular basalt or weathered cinder without testing.
