igneous
Basalt Pebble
Aphanitic Extrusive Igneous Rock
AI-generated identification · may be incorrectHardness 6 on Mohs scale, dark gray to black color, dull to sub-metamorphic luster, fine-grained aphanitic crystal structure, lacks prominent cleavage, specific gravity around 2.9-3.0.
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Physical properties
Hardness 6 on Mohs scale, dark gray to black color, dull to sub-metamorphic luster, fine-grained aphanitic crystal structure, lacks prominent cleavage, specific gravity around 2.9-3.0.
Formation & geological history
Formed from the rapid cooling of low-viscosity, mafic lava flows at the Earth's surface, common in volcanic regions and oceanic crust.
Uses & applications
Used in construction, aggregate for concrete, road base material, and decorative landscaping stones.
Geological facts
Basalt is the most common rock type in the Earth's crust underlying the world's ocean basins, and is also found on the Moon and Mars.
Field identification & locations
Identify by its dark, dense, fine-grained appearance and rounded shape from water tumbling in rivers or beaches; widely distributed globally.
