igneous
Basalt
Mafic Igneous Rock
Hardness: 6-7 (Mohs scale); Color: Dark grey to black; Luster: Dull/earthy; Crystal structure: Aphanitic (fine-grained); Cleavage: Non-existent; Specific Gravity: 2.8 - 3.0
- Hardness
- 6-7 (Mohs scale)
- Color
- Dark grey to black
- Luster
- Dull/earthy
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Physical properties
Hardness: 6-7 (Mohs scale); Color: Dark grey to black; Luster: Dull/earthy; Crystal structure: Aphanitic (fine-grained); Cleavage: Non-existent; Specific Gravity: 2.8 - 3.0
Formation & geological history
Formed from the rapid cooling of magnesium-rich and iron-rich lava at or very near the surface of a terrestrial planet or a moon.
Uses & applications
Used primarily in construction (crushed stone, concrete aggregate), road base, and as high-quality building stone or paving sets.
Geological facts
Basalt is the most common rock type in the Earth's crust and makes up most of the ocean floor. Large parts of the Moon and Mars are also covered in basaltic plains.
Field identification & locations
Identify by its dark color, heavy weight (density), and lack of visible crystals. It is commonly found in volcanic regions and on beaches where volcanic activity occurred.
