igneous
Vesicular basalt (lava rock)
Basalt, a mafic volcanic rock composed mainly of plagioclase feldspar and pyroxene, commonly with olivine
AI-generated identification · may be incorrectDark gray-brown, fine-grained groundmass with abundant rounded gas vesicles; typically Mohs 5–6, dull to slightly glassy, with no obvious cleavage. The cavities may be lined or partly filled with minerals, but none are clearly identifiable here.
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Physical properties
Dark gray-brown, fine-grained groundmass with abundant rounded gas vesicles; typically Mohs 5–6, dull to slightly glassy, with no obvious cleavage. The cavities may be lined or partly filled with minerals, but none are clearly identifiable here.
Formation & geological history
Formed when gas-rich basaltic lava cooled rapidly at or near the surface; its age cannot be determined from the image. Vesicular basalts occur in volcanic regions and lava flows worldwide.
Uses & applications
Used as decorative stone, landscaping material, and sometimes construction aggregate; attractive pieces are collected as geological specimens.
Geological facts
The rounded holes are vesicles left by gas bubbles trapped as lava solidified. This specimen’s unusually dense, regular cavities may also reflect biological boring or weathering, so a closer examination would help confirm their origin.
Field identification & locations
Look for a dark, fine-grained volcanic matrix and bubble-shaped cavities; distinguish it from coral or other fossil material by checking whether the holes cut through the rock or contain mineral infill. Common in volcanic terrains.
