igneous
Vesicular Basalt
Extrusive mafic igneous rock
Hardness: 5-6 (Mohs scale), Color: Dark gray to reddish-brown, Luster: Dull/Earthy, Structure: Vesicular (pitted with gas bubbles), Specific Gravity: 2.8–3.0
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Physical properties
Hardness: 5-6 (Mohs scale), Color: Dark gray to reddish-brown, Luster: Dull/Earthy, Structure: Vesicular (pitted with gas bubbles), Specific Gravity: 2.8–3.0
Formation & geological history
Formed from the rapid cooling of magnesium-rich and iron-rich lava at or very near the Earth's surface, where trapped gases expand to create holes (vesicles).
Uses & applications
Used in landscaping (lava rocks), aggregate for concrete and asphalt, and sometimes as a natural pumice substitute for skin exfoliation.
Geological facts
The holes in the rock were once gas bubbles trapped in molten lava. Basalt is the most common rock type on Earth's crust and even makes up much of the lunar surface.
Field identification & locations
Look for a lightweight, porous appearance with many visible small or medium-sized holes. Found in volcanic regions like Hawaii, Iceland, and the Pacific Northwest.
