igneous
Vesicular basalt (likely scoria)
Basaltic volcanic rock; primarily plagioclase, pyroxene, and olivine, with abundant gas vesicles
AI-generated identification · may be incorrectDark gray-brown, fine-grained, porous, and dull to slightly earthy luster; typically Mohs 5–6, with no visible cleavage and low-to-moderate specific gravity due to vesicles. The rounded shape appears naturally water-worn or human-tumbled.
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Physical properties
Dark gray-brown, fine-grained, porous, and dull to slightly earthy luster; typically Mohs 5–6, with no visible cleavage and low-to-moderate specific gravity due to vesicles. The rounded shape appears naturally water-worn or human-tumbled.
Formation & geological history
Formed when fluid basaltic lava cooled rapidly at or near Earth’s surface, trapping gas bubbles; commonly Cenozoic to Recent, though basalt occurs throughout geologic time. Exact age and locality cannot be determined from the photograph.
Uses & applications
Used as lightweight aggregate, road material, landscaping stone, and occasionally abrasives; generally not a jewelry gemstone. A fine labeled specimen may have modest educational or collector interest.
Geological facts
Vesicles are preserved bubbles from volcanic gases; abundant, irregular pores distinguish scoria or vesicular basalt from dense basalt. Its brown color may reflect oxidation of iron-bearing minerals.
Field identification & locations
Identify by its dark mafic color, fine texture, hardness, and numerous irregular holes; a streak, density, and fresh broken surface would improve identification. Common near volcanic fields, lava flows, and shorelines draining volcanic terrain.
