igneous
Basalt Pebble
Extrusive Igneous Rock
AI-generated identification · may be incorrectHardness of 6 on the Mohs scale, dark grey to black color, dull luster, microcrystalline or aphanitic texture, and lacks prominent cleavage.
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Physical properties
Hardness of 6 on the Mohs scale, dark grey to black color, dull luster, microcrystalline or aphanitic texture, and lacks prominent cleavage.
Formation & geological history
Formed from the rapid cooling of mafic lava exposed at or near the surface of a planet or moon, typically through volcanic activity.
Uses & applications
Used in construction as crushed stone for road bases, concrete aggregate, and railroad ballast, as well as in landscaping.
Geological facts
Basalt is the most common rock type in the Earth's crust underlying the world's oceans and also forms extensive geological formations like the Columbia River Basalt Group.
Field identification & locations
Identified by its fine-grained dark appearance and dense composition; commonly found in riverbeds and beaches where it has been smoothed by water erosion.
