igneous
Basalt Pebble
Aphanitic Igneous Rock
AI-generated identification · may be incorrectHardness of 6 on Mohs scale, dark gray to black color, dull luster, microcrystalline or glassy crystal structure with high specific gravity.
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Physical properties
Hardness of 6 on Mohs scale, dark gray to black color, dull luster, microcrystalline or glassy crystal structure with high specific gravity.
Formation & geological history
Formed from the rapid cooling of magnesium- and iron-rich lava exposed at or very near the Earth's surface.
Uses & applications
Used in construction, aggregate, railroad ballast, and sometimes in landscaping or stonemasonry.
Geological facts
Basalt is the most common rock type in the Earth's crust underlying the world's ocean basins and forming much of the volcanic islands.
Field identification & locations
Identify in the field by its dark, fine-grained matrix; commonly found in riverbeds, beaches, and volcanic regions.
