igneous
Basalt Pebble
Basalt
Hardness: 6.0; Color: Dark grey to black; Luster: Dull or earthy; Crystal structure: Aphanitic (fine-grained); Specific gravity: 2.9–3.1
- Hardness
- 6
- Color
- Dark grey to black
- Luster
- Dull or earthy
Identified More igneous →
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Physical properties
Hardness: 6.0; Color: Dark grey to black; Luster: Dull or earthy; Crystal structure: Aphanitic (fine-grained); Specific gravity: 2.9–3.1
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.
Uses & applications
Used in construction as crushed stone for road base, concrete aggregate, and railroad ballast, or for stone carvings and decorative landscaping.
Geological facts
Basalt is the most common rock type in the Earth's crust and makes up most of the ocean floor; it has also been identified on the Moon, Mars, and Venus.
Field identification & locations
Identify by its dark color, heavy weight (relative to size), and very fine-grained texture; commonly found on beaches, near volcanic sites, and in riverbeds.
