igneous
Basalt
Mafic Igneous Rock (primarily Plagioclase and Pyroxene)
Hardness: 6.0; Color: Dark grey to black; Luster: Dull to sub-metallic; Structure: Fine-grained/aphanitic; Cleavage: None; Specific Gravity: 2.8–3.0
- Hardness
- 6
- Color
- Dark grey to black
- Luster
- Dull to sub-metallic
Identified More igneous →
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Physical properties
Hardness: 6.0; Color: Dark grey to black; Luster: Dull to sub-metallic; Structure: Fine-grained/aphanitic; Cleavage: None; 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 Earth surface. This specimen appears potentially vesicular or weathered, formed in volcanic environments.
Uses & applications
Used primarily in construction for aggregate, road base, railroad ballast, and ground-up for industrial floor tiles or stone wool insulation.
Geological facts
Basalt is the most common rock type in the Earth's crust and makes up most of the ocean floor. It is also found on the Moon and Mars.
Field identification & locations
Identify by its dark color, heavy weight (density), and fine-grained texture. Commonly found in volcanic regions, lava fields, and oceanic ridges.
