igneous
Vesicular basalt (likely)
Vesicular basalt; chiefly plagioclase and pyroxene, possibly olivine, with gas-bubble vesicles
AI-generated identification · may be incorrectDark gray, fine-grained matrix with rounded cavities and pale mineral patches; typically Mohs 5–6, dull to slightly glassy, with no obvious cleavage. The image alone cannot confirm the pale patches’ identity or exact composition.
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Physical properties
Dark gray, fine-grained matrix with rounded cavities and pale mineral patches; typically Mohs 5–6, dull to slightly glassy, with no obvious cleavage. The image alone cannot confirm the pale patches’ identity or exact composition.
Formation & geological history
Forms when gas-rich basaltic lava cools quickly at or near the surface, trapping bubbles. It may be geologically recent or ancient; age cannot be determined from appearance.
Uses & applications
Basalt is widely used as crushed aggregate, road stone, and building stone; vesicular pieces are mainly collected or used decoratively.
Geological facts
The holes are vesicles left by gas bubbles, unlike the mineral-filled cavities called amygdules.
Field identification & locations
Look for a dark, fine-grained volcanic rock with rounded holes and a relatively heavy feel; common in volcanic regions and lava flows worldwide. A photo cannot rule out other porous rocks or identify its locality.
