igneous
Basalt River Stone
Aphanitic mafic extrusive igneous rock
AI-generated identification · may be incorrectHardness 6 on Mohs scale, dark gray to black color, fine-grained aphanitic texture, dull luster, specific gravity around 2.8 to 3.0.
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Physical properties
Hardness 6 on Mohs scale, dark gray to black color, fine-grained aphanitic texture, dull luster, specific gravity around 2.8 to 3.0.
Formation & geological history
Formed from the rapid cooling of low-viscosity basaltic lava flows at the Earth's surface, often rounded by water transport in riverbeds.
Uses & applications
Used widely in construction aggregates, railroad ballast, dimension stone, and landscaping materials.
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, fine grain size where individual crystals are not visible to the naked eye, and high density. Found worldwide.
