igneous
Vesicular Basalt
Basalt (Mafic Extrusive Igneous Rock)
Hardness: 6 (Mohs), Color: Dark grey to black, Luster: Dull/Earthy, Crystal Structure: Aphanitic (fine-grained), includes vesicles (gas bubbles), Specific Gravity: 2.8-3.0
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Physical properties
Hardness: 6 (Mohs), Color: Dark grey to black, Luster: Dull/Earthy, Crystal Structure: Aphanitic (fine-grained), includes vesicles (gas bubbles), Specific Gravity: 2.8-3.0
Formation & geological history
Formed from the rapid cooling of magnesium-rich and iron-rich lava at the Earth's surface. The small holes, or vesicles, are formed by gas bubbles that were trapped in the lava as it solidified.
Uses & applications
Used in construction for road base, concrete aggregate, and railroad ballast. Also popular as landscape stone, 'lava rocks' for grills, and in stone therapy.
Geological facts
Basalt is the most common rock type in the Earth's crust and makes up most of the ocean floor. It is also found extensively on the Moon and Mars.
Field identification & locations
Identify by its dark color, heavy weight (dense composition), and the presence of small holes or pits. It is commonly found in volcanic fields, oceanic islands, and mid-ocean ridges.
