igneous
Red vesicular volcanic rock, likely scoria
Scoria (mafic volcanic rock; commonly basaltic, composed mainly of plagioclase, pyroxene, and iron-rich glass)
AI-generated identification · may be incorrectDark red to maroon, porous, matte to dull luster, with abundant gas vesicles; typically 5–6 Mohs and low-to-moderate density. The rounded shape appears tumbled or naturally water-worn, and the color may be oxidation-enhanced.
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Physical properties
Dark red to maroon, porous, matte to dull luster, with abundant gas vesicles; typically 5–6 Mohs and low-to-moderate density. The rounded shape appears tumbled or naturally water-worn, and the color may be oxidation-enhanced.
Formation & geological history
Forms when gas-rich basaltic lava cools rapidly, trapping bubbles; red coloration develops through oxidation of iron during or after eruption. Commonly Quaternary to Recent around cinder cones, lava flows, and volcanic fields.
Uses & applications
Used as lightweight landscaping stone, drainage aggregate, barbecue media when specifically manufactured for that purpose, and decorative rock; generally has little jewelry value.
Geological facts
Scoria is typically denser and less glassy than pumice, so it may sink in water. Vesicle size and abundance reflect gases escaping from erupting magma.
Field identification & locations
Identify by its lightweight, highly vesicular texture, rough surface, and reddish oxidized color; common in volcanic regions such as Hawaii, the western United States, Iceland, Italy, and New Zealand. Avoid assuming it is slag without checking for irregular industrial glassy textures or metallic inclusions.
