igneous
Vesicular basalt (probable)
Basalt, typically composed of plagioclase, pyroxene, and olivine
AI-generated identification · may be incorrectDark gray to brown, fine-grained, dull luster, with abundant small vesicles and a weathered pale surface; hardness about 5–6, massive texture, and no obvious cleavage. The image alone cannot confirm mineral composition or distinguish it from weathered scoria.
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Physical properties
Dark gray to brown, fine-grained, dull luster, with abundant small vesicles and a weathered pale surface; hardness about 5–6, massive texture, and no obvious cleavage. The image alone cannot confirm mineral composition or distinguish it from weathered scoria.
Formation & geological history
An extrusive volcanic rock formed when iron- and magnesium-rich lava cooled rapidly at or near Earth’s surface, commonly during eruptions from the Cenozoic to the present. Vesicles formed from gas bubbles trapped in cooling lava.
Uses & applications
Used as crushed aggregate, road base, riprap, and occasionally as decorative stone; collectible value is generally minimal unless it is an unusual locality specimen.
Geological facts
Its apparent pores are gas-bubble cavities rather than sedimentary holes; weathering can produce the cream-colored rind visible here.
Field identification & locations
Identify by its heavy feel, fine texture, volcanic appearance, and lack of visible sand grains or fossils; a streak, density test, and fresh broken surface would help confirm it. Common worldwide in volcanic provinces, oceanic crust, and basalt flows.
