igneous
Red vesicular volcanic rock, likely scoria
Scoria (mafic pyroclastic rock), typically basaltic and composed mainly of plagioclase, pyroxene, and iron-rich glass
AI-generated identification · may be incorrectDark reddish-brown, fine-grained, porous, and dull to slightly earthy; hardness about 5–6 Mohs, with irregular fracture and abundant gas vesicles. The apparent elongated cavities and rough surface are characteristic of scoria, though weathered vesicular basalt is possible.
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Physical properties
Dark reddish-brown, fine-grained, porous, and dull to slightly earthy; hardness about 5–6 Mohs, with irregular fracture and abundant gas vesicles. The apparent elongated cavities and rough surface are characteristic of scoria, though weathered vesicular basalt is possible.
Formation & geological history
Forms when gas-rich basaltic lava erupts and rapidly cools, trapping bubbles; oxidation of iron produces the red-brown color. Most examples are geologically young, commonly Quaternary, though scoria occurs in volcanic rocks of many ages.
Uses & applications
Used as lightweight aggregate, landscaping stone, drainage material, abrasive, and sometimes in concrete or cinder blocks; generally little jewelry value.
Geological facts
Scoria is denser and typically darker than pumice because it forms from iron- and magnesium-rich magma. Its vesicles may be partly filled by later minerals such as zeolites or calcite.
Field identification & locations
Look for a lightweight, nonlayered volcanic fragment with irregular pores, reddish oxidation, and no visible mineral grains; it may attract a weak magnet if iron-rich. Common around cinder cones, lava fields, and basaltic volcanoes worldwide.
