igneous
Vesicular Basalt
Extrusive mafic igneous rock
AI-generated identification · may be incorrectHardness of 6 on the Mohs scale, dark gray to black color, dull luster, fine-grained aphanitic crystal structure, and distinctive gas-bubble cavities (vesicles).
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Physical properties
Hardness of 6 on the Mohs scale, dark gray to black color, dull luster, fine-grained aphanitic crystal structure, and distinctive gas-bubble cavities (vesicles).
Formation & geological history
Formed from the rapid cooling of low-viscosity, gas-rich basaltic lava flows at the Earth's surface.
Uses & applications
Used widely in aggregate for construction, railroad ballast, landscaping, and occasionally as decorative stone.
Geological facts
The characteristic holes are formed by trapped gas bubbles that escaped as the molten lava solidified. When these vesicles later fill with secondary minerals, the rock is known as amygdaloidal basalt.
Field identification & locations
Easily identified by its dark, fine-grained matrix peppered with small rounded or irregular holes. Found globally in volcanic provinces, oceanic crusts, and continental flood basalt regions.
