igneous
Basalt
Basalt
Hardness: 6.0; Color: Dark grey to black; Luster: Dull to sub-metallic; Crystal structure: Aphanitic (fine-grained); Specific gravity: 2.8-3.0; Contains plagioclase feldspar, pyroxene, and olivine.
- Hardness
- 6
- Color
- Dark grey to black
- Luster
- Dull to sub-metallic
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Physical properties
Hardness: 6.0; Color: Dark grey to black; Luster: Dull to sub-metallic; Crystal structure: Aphanitic (fine-grained); Specific gravity: 2.8-3.0; Contains plagioclase feldspar, pyroxene, and olivine.
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 a moon. It is the most common volcanic rock on Earth.
Uses & applications
Extensively used in construction, such as aggregate for roads, railroad ballast, and concrete. It is also used as a dimension stone for flooring, monuments, and landscaping.
Geological facts
Basalt is the most common rock in Earth's crust and makes up most of the ocean floor. It is also found on the Moon, Mars, and Venus.
Field identification & locations
Identify in the field by its dark color, heavy weight (density), and lack of visible crystals without a magnifying glass. It is commonly found in volcanic regions, oceanic crust, and riverbeds near volcanic flows.
