igneous
Scoriaceous basalt (scoria)
Vesicular basalt; primarily plagioclase, pyroxene, olivine, and volcanic glass
AI-generated identification · may be incorrectDark gray, vesicular, rough, and typically glassy to dull; hardness about 5–6 Mohs, no consistent cleavage, fine-grained matrix, and specific gravity commonly 2.0–2.7 because of abundant gas cavities.
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Physical properties
Dark gray, vesicular, rough, and typically glassy to dull; hardness about 5–6 Mohs, no consistent cleavage, fine-grained matrix, and specific gravity commonly 2.0–2.7 because of abundant gas cavities.
Formation & geological history
An extrusive igneous rock formed when gas-rich basaltic lava cooled rapidly, trapping bubbles; commonly associated with young volcanic cones, lava flows, and cinder deposits, generally ranging from Holocene to much older volcanic ages.
Uses & applications
Used as lightweight aggregate, landscaping stone, drainage material, barbecue media, and occasionally as an abrasive or decorative stone; it has little jewelry value.
Geological facts
Scoria is denser and darker than pumice, while its vesicles are usually larger and its surface more rugged. The specimen’s appearance is consistent with scoria, though a photo cannot exclude weathered vesicular basalt or industrial slag.
Field identification & locations
Identify it by its dark basaltic color, abundant irregular holes, rough texture, and nonmetallic appearance; it commonly occurs near basaltic volcanoes worldwide, including Hawaii, Iceland, Mexico, and the western United States.
