igneous
Weathered vesicular volcanic rock (likely scoria or vesicular basalt)
Vesicular basalt/scoria; primarily plagioclase, pyroxene, olivine, and volcanic glass
AI-generated identification · may be incorrectGray-tan, rounded, and heavily vesicular with dark weathering patches; typically dull to slightly earthy luster, no visible cleavage, and Mohs hardness about 5–6. Specific gravity is commonly 2.0–2.8, reduced by abundant gas cavities.
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Physical properties
Gray-tan, rounded, and heavily vesicular with dark weathering patches; typically dull to slightly earthy luster, no visible cleavage, and Mohs hardness about 5–6. Specific gravity is commonly 2.0–2.8, reduced by abundant gas cavities.
Formation & geological history
Formed when basaltic lava cooled rapidly while escaping gas created vesicles; likely Cenozoic or younger, though age cannot be determined from the photograph. Rounding and surface alteration suggest transport or prolonged weathering.
Uses & applications
Used as lightweight aggregate, landscaping stone, abrasive, and occasionally in cement products; generally little jewelry value.
Geological facts
Scoria is usually darker and denser than pumice, while pumice can float because of extreme porosity. The mottled surface may reflect iron-oxide weathering or lichen staining.
Field identification & locations
Identify by its irregular gas cavities, volcanic texture, and relatively lightweight feel; a streak, density test, and fresh broken surface would distinguish it from weathered concrete. Common around basaltic volcanic fields and cinder cones.
