igneous
Basalt Pebble
Aphanitic Extrusive Igneous Rock
AI-generated identification · may be incorrectHardness: 6 on Mohs scale, Color: Dark grey to black, Luster: Dull to sub-vitreous, Crystal structure: Microcrystalline or cryptocrystalline.
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Physical properties
Hardness: 6 on Mohs scale, Color: Dark grey to black, Luster: Dull to sub-vitreous, Crystal structure: Microcrystalline or cryptocrystalline.
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 as aggregate, railroad ballast, and in the production of stone wool insulation.
Geological facts
Basalt is the most common rock type in the Earth's oceanic crust and also makes up extensive volcanic formations on the Moon and Mars.
Field identification & locations
Identify by its dense, dark, fine-grained matrix and smooth water-worn surface when found in riverbeds or beaches.
