igneous
Scoria (vesicular volcanic rock)
Scoria, typically basaltic or andesitic volcanic material
AI-generated identification · may be incorrectReddish-brown, porous and vesicular, with a dull to slightly glassy luster; composed mainly of plagioclase, pyroxene, and volcanic glass. Hardness varies, commonly about 5–6 Mohs; the visible cavities are gas bubbles preserved as the lava cooled.
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Physical properties
Reddish-brown, porous and vesicular, with a dull to slightly glassy luster; composed mainly of plagioclase, pyroxene, and volcanic glass. Hardness varies, commonly about 5–6 Mohs; the visible cavities are gas bubbles preserved as the lava cooled.
Formation & geological history
Forms when gas-rich lava erupts and cools rapidly, trapping abundant vesicles. It is generally geologically young and associated with volcanic cones and lava flows.
Uses & applications
Used as lightweight landscaping stone, drainage aggregate, and abrasive; attractive pieces are kept as geological curiosities.
Geological facts
Scoria is less vesicular and generally denser than pumice, and its red color commonly results from oxidation of iron during cooling.
Field identification & locations
Identify it by its lightweight, rough, bubble-filled surface and dark or reddish volcanic color. Found near basaltic volcanoes worldwide; the photograph alone cannot confirm its origin.
