igneous
Basalt Pebble (Shaped)
Extrusive Igneous Rock
Hardness: 6 on Mohs scale, Color: Dark grey to black, Luster: Dull to sub-vitreous, Crystal structure: Aphanitic (fine-grained), Cleavage: None, Specific gravity: 2.8-3.0
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Physical properties
Hardness: 6 on Mohs scale, Color: Dark grey to black, Luster: Dull to sub-vitreous, Crystal structure: Aphanitic (fine-grained), Cleavage: None, Specific gravity: 2.8-3.0
Formation & geological history
Formed from the rapid cooling of low-viscosity lava rich in magnesium and iron exposed at or very near the Earth's surface.
Uses & applications
Used in construction, aggregate, cobblestones, and carved or tumbled decorative objects.
Geological facts
Basalt is the most common rock type in the Earth's oceanic crust and is also found abundantly on the Moon and Mars.
Field identification & locations
Identified by its dark color and fine-grained texture. Commonly found in volcanic regions worldwide and riverbeds where weathering rounds the stones.
