igneous
Vesicular Basalt
Aphanitic Mafic Igneous Rock (with Vesicular Texture)
Hardness: 5-6 (Mohs), Color: Dark grey, black, or reddish-brown, Luster: Dull or earthy, Structure: Fine-grained with holes (vesicles), Specific Gravity: 2.8-3.0
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Physical properties
Hardness: 5-6 (Mohs), Color: Dark grey, black, or reddish-brown, Luster: Dull or earthy, Structure: Fine-grained with holes (vesicles), Specific Gravity: 2.8-3.0
Formation & geological history
Formed from the rapid cooling of magnesium-rich and iron-rich lava. The holes are caused by gas bubbles that were trapped in the lava as it solidified near the Earth's surface.
Uses & applications
Commonly used in landscaping as decorative 'lava rock', in road construction as aggregate, and sometimes in industrial abrasive applications.
Geological facts
Basalt is the most common rock in the Earth's crust and makes up the majority of the ocean floor. Vesicular basalt can be light enough to float temporarily if the gas pockets are numerous enough.
Field identification & locations
Identified by its dark color and distinctive pitted, 'holey' surface. Found in volcanic regions like Hawaii, Iceland, and the Pacific Northwest of the USA.
