igneous
Basalt Pebble
Mafic Extrusive Igneous Rock
AI-generated identification · may be incorrectHardness of 6 on the Mohs scale; dark black to dark gray color; aphanitic texture with a dull to submetallic luster; high specific gravity around 2.9 to 3.0.
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Physical properties
Hardness of 6 on the Mohs scale; dark black to dark gray color; aphanitic texture with a dull to submetallic luster; high specific gravity around 2.9 to 3.0.
Formation & geological history
Formed from the rapid cooling of magnesium- and iron-rich lava flows at the Earth's surface, dating across various geological eras.
Uses & applications
Used widely in construction as crushed stone, railroad ballast, aggregate in concrete, and occasionally in stone-age tools.
Geological facts
Basalt is the most common rock type in the Earth's crust beneath the oceans and also forms major volcanic features on the Moon and Mars.
Field identification & locations
Easily identified in the field by its very fine-grained dark matrix and heavy weight; found abundantly worldwide in volcanic regions and riverbeds.
