igneous
Basalt Gravel
Basalt
Hardness: 6 (Mohs); Color: Dark gray to black; Luster: Dull to sub-metallic; Crystal structure: Aphanitic (fine-grained); Specific gravity: 2.8-3.0
- Hardness
- 6 (Mohs)
- Color
- Dark gray to black
- Luster
- Dull to sub-metallic
Identified More igneous →
Explore Basalt Gravel in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6 (Mohs); Color: Dark gray to black; Luster: Dull to sub-metallic; Crystal structure: Aphanitic (fine-grained); 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's surface. Basalt is the most common volcanic rock on Earth.
Uses & applications
Commonly used as crushed stone for construction, road base, railroad ballast, and as a component in concrete and asphalt surfaces.
Geological facts
Basalt makes up most of the Earth's ocean floor. It is also found on the Moon and Mars, forming large lunar plains known as 'maria'.
Field identification & locations
Identify by its weighty feel, dark color, and lack of visible individual crystals without magnification. Commonly found in areas with past or present volcanic activity.
