igneous
Vesicular Basalt
Extrusive Igneous Rock
Hardness of 6 on the Mohs scale; dark gray to greenish-gray or black in color; dull to submetallic luster; fine-grained, aphanitic texture with prominent gas cavities (vesicles); specific gravity around 2.8 - 3.0
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Physical properties
Hardness of 6 on the Mohs scale; dark gray to greenish-gray or black in color; dull to submetallic luster; fine-grained, aphanitic texture with prominent gas cavities (vesicles); specific gravity around 2.8 - 3.0
Formation & geological history
Formed from the rapid cooling of low-viscosity, gas-rich basaltic lava flows on the Earth's surface, where escaping gas bubbles create the characteristic pitted or vesicular texture.
Uses & applications
Used in construction, road aggregate, railroad ballast, and occasionally as decorative stone or lightweight aggregate.
Geological facts
Vesicular basalt is one of the most common rock types on Earth's surface and makes up most of the oceanic crust as well as extensive continental flood basalts.
Field identification & locations
Easily identified by its dark, fine-grained matrix and characteristic rounded holes (vesicles) left by trapped gas bubbles; commonly found in volcanic regions worldwide.
