igneous
Vesicular basalt (possibly scoriaceous basalt)
Vesicular basalt; chiefly plagioclase, pyroxene, and iron-rich oxides
AI-generated identification · may be incorrectDark purplish-brown, fine-grained volcanic rock with rounded gas-bubble cavities (vesicles); typically Mohs 5–6, dull to slightly vitreous, with no obvious cleavage. The image alone cannot establish its exact composition or whether the cavities are natural.
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Physical properties
Dark purplish-brown, fine-grained volcanic rock with rounded gas-bubble cavities (vesicles); typically Mohs 5–6, dull to slightly vitreous, with no obvious cleavage. The image alone cannot establish its exact composition or whether the cavities are natural.
Formation & geological history
Forms when basaltic lava cools quickly while trapped gas escapes, leaving vesicles; commonly associated with relatively recent volcanic flows, though a specimen’s age cannot be determined from appearance.
Uses & applications
Used as decorative stone, landscaping material, and occasionally lightweight aggregate; porous specimens are also collected.
Geological facts
Vesicles are the frozen remnants of gas bubbles in lava; mineral-filled cavities are called amygdales.
Field identification & locations
Look for a dense, dark volcanic groundmass containing scattered rounded holes; distinguish it from industrial slag by geological context and consistent natural texture. Basalt occurs worldwide in volcanic regions.
