igneous
Red scoria (vesicular basalt)
Scoriaceous basalt; chiefly plagioclase, pyroxene, and iron-rich volcanic glass
AI-generated identification · may be incorrectUsually dark red-brown to black, highly porous, and dull to slightly earthy; hardness about 5–6 Mohs, with no consistent cleavage and low-to-moderate specific gravity. The vesicles are gas bubbles, and the reddish color reflects oxidation of iron.
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Physical properties
Usually dark red-brown to black, highly porous, and dull to slightly earthy; hardness about 5–6 Mohs, with no consistent cleavage and low-to-moderate specific gravity. The vesicles are gas bubbles, and the reddish color reflects oxidation of iron.
Formation & geological history
An extrusive volcanic rock formed when basaltic lava cooled rapidly while escaping dissolved gases; commonly Quaternary to modern in age. It occurs in cinder cones, lava flows, and volcanic fields.
Uses & applications
Used as lightweight landscaping stone, drainage aggregate, road fill, and occasionally in abrasive or decorative applications; generally little jewelry value.
Geological facts
Scoria is less dense and more vesicular than ordinary basalt but typically denser and darker than pumice. This specimen appears rounded or tumbled and may have surface coating or weathering.
Field identification & locations
Identify it by abundant irregular pores, rough texture, reddish-brown color, and magnetic response from iron-bearing minerals; common sources include Hawaii, Iceland, the western United States, Italy, and Mexico.
