igneous
Red vesicular volcanic rock, likely scoria
Scoria (vesicular basalt/andesite), composition mainly plagioclase, pyroxene, iron oxides, and volcanic glass
AI-generated identification · may be incorrectTypically dark red to black, highly vesicular, rough, and dull to glassy; Mohs hardness about 5–6, with no visible cleavage and relatively low density due to abundant gas cavities. The specimen appears rounded or shaped, so surface color and texture may be altered by weathering or processing.
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Physical properties
Typically dark red to black, highly vesicular, rough, and dull to glassy; Mohs hardness about 5–6, with no visible cleavage and relatively low density due to abundant gas cavities. The specimen appears rounded or shaped, so surface color and texture may be altered by weathering or processing.
Formation & geological history
Forms when gas-rich basaltic to andesitic lava cools rapidly, trapping bubbles; its red color commonly results from oxidation of iron during or after eruption. It is generally Quaternary to recent, though older volcanic examples are widespread.
Uses & applications
Used as lightweight aggregate, drainage material, landscaping rock, abrasive, and soil amendment; occasionally used decoratively, but it is not usually a jewelry gemstone.
Geological facts
Scoria is denser and generally darker than pumice, whose bubbles are more abundant and whose overall density can be low enough to float. The rounded shape may indicate a landscaping or tumbled specimen rather than an unmodified outcrop fragment.
Field identification & locations
Identify it by its reddish-black color, abundant irregular holes, rough texture, and light weight compared with solid basalt. Common sources include volcanic regions such as Mexico, Italy, Iceland, the western United States, and Hawaii.
