igneous
Basalt
Mafic Extrusive Igneous Rock
Hardness: 6 on Mohs scale. Color: Dark gray to black. Luster: Earthy, dull to slightly glistening. Texture: Aphanitic (fine-grained), crystalline structure. Specific Gravity: 2.8-3.0.
- Hardness
- 6 on Mohs scale
- Color
- Dark gray to black
- Luster
- Earthy, dull to slightly glistening
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Physical properties
Hardness: 6 on Mohs scale. Color: Dark gray to black. Luster: Earthy, dull to slightly glistening. Texture: Aphanitic (fine-grained), crystalline structure. 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 for road bases, concrete aggregate, railroad ballast, and dimension stone for paving.
Geological facts
Basalt is the most common rock type in the Earth's crust, forming most of the oceanic crust. It is also extremely common on the Moon and Mars.
Field identification & locations
Identify by its dark gray color, fine-grained texture, and heavy density relative to size. Very common in volcanic regions and ocean floor formations.
