igneous
Vesicular basalt (likely weathered scoria)
Basaltic volcanic rock; chiefly plagioclase, pyroxene, and iron-rich olivine, with vesicles
AI-generated identification · may be incorrectDark reddish-brown, fine-grained, dull to slightly vitreous, with numerous rounded gas cavities and rusty weathering; hardness about 5–6 Mohs, no obvious cleavage, typical specific gravity 2.7–3.0.
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Physical properties
Dark reddish-brown, fine-grained, dull to slightly vitreous, with numerous rounded gas cavities and rusty weathering; hardness about 5–6 Mohs, no obvious cleavage, typical specific gravity 2.7–3.0.
Formation & geological history
An extrusive igneous rock formed when low-viscosity basaltic lava cooled rapidly at or near Earth’s surface, trapping gas bubbles; the red color reflects oxidation of iron minerals during weathering. Exact age cannot be determined from the photograph.
Uses & applications
Used as aggregate, road stone, landscaping material, and sometimes as lightweight abrasive or garden rock; generally little jewelry value.
Geological facts
The holes are vesicles, not fossils, and indicate degassing during eruption. More porous, lighter pieces are commonly called scoria; denser pieces are vesicular basalt.
Field identification & locations
Identify it by its heavy feel, fine texture, magnetic response in some specimens, and abundant irregular vesicles; common in volcanic regions, including Hawaii, Iceland, Mexico, and the western United States. The image alone cannot establish a precise locality or species.
