igneous
Basalt Pebble
Mafic extrusive igneous rock
Hardness: 6 on Mohs scale; Color: Dark grey to black; Luster: Dull, earthy; Texture: Aphanitic (fine-grained); Specific Gravity: 2.8-3.0
- Hardness
- 6 on Mohs scale
- Color
- Dark grey to black
- Luster
- Dull, earthy
Identified More igneous →
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Physical properties
Hardness: 6 on Mohs scale; Color: Dark grey to black; Luster: Dull, earthy; Texture: Aphanitic (fine-grained); Specific Gravity: 2.8-3.0
Formation & geological history
Formed from the rapid cooling of magnesium-rich and iron-rich lava exposed at or very near the surface of a terrestrial planet or moon.
Uses & applications
Widely used in construction as crushed stone, concrete aggregate, road base, and ballast for railroad tracks. Also used for stone carvings and statues.
Geological facts
Basalt is the most common rock type in the Earth's crust, making up most of the oceanic crust. It is also extremely common on the Moon and Mars.
Field identification & locations
Identified by its dark color, heavy weight relative to size, and fine-grained texture. Commonly found in volcanic regions, riverbeds, and beaches worldwide.
