igneous
Scoria (vesicular volcanic rock)
Basaltic scoria; chiefly plagioclase, pyroxene, olivine, and volcanic glass
AI-generated identification · may be incorrectTypically dark gray to reddish-brown, highly vesicular, rough, and dull to slightly glassy; hardness about 5–6 Mohs, with no prominent cleavage and low density due to abundant gas cavities.
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Physical properties
Typically dark gray to reddish-brown, highly vesicular, rough, and dull to slightly glassy; hardness about 5–6 Mohs, with no prominent cleavage and low density due to abundant gas cavities.
Formation & geological history
Forms when gas-rich basaltic magma erupts and rapidly cools, trapping bubbles in the lava; commonly Quaternary to modern volcanic material. The reddish patches may reflect oxidation of iron-bearing minerals.
Uses & applications
Used as lightweight aggregate, landscaping stone, drainage material, abrasive, and sometimes in horticulture; generally not a jewelry stone.
Geological facts
Scoria differs from pumice because it is darker, denser, and usually has thicker cavity walls. Its vesicles record dissolved volcanic gases escaping during eruption.
Field identification & locations
Identify it by its black, brown, or red color, abundant irregular holes, rough texture, and ability to feel unusually light; common near cinder cones, lava flows, and basaltic volcanoes worldwide.
