igneous
Basalt (Vesicular)
Basalt
Hardness: 5-6 Mohs. Color: dark gray to black or reddish-brown. Luster: dull to earthy. Structure: fine-grained (aphanitic) with small vesicles (holes). Specific gravity: 2.8-3.0.
- Hardness
- 5-6 Mohs
- Color
- dark gray to black or reddish-brown
- Luster
- dull to earthy
Identified More igneous →
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Physical properties
Hardness: 5-6 Mohs. Color: dark gray to black or reddish-brown. Luster: dull to earthy. Structure: fine-grained (aphanitic) with small vesicles (holes). 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. This specific piece shows a vesicular texture from trapped gas bubbles during eruption.
Uses & applications
Used primarily in construction for crushed stone, aggregate, and railroad ballast. Also used as high-temperature insulation in the form of rock wool.
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 extensively on the Moon and Mars.
Field identification & locations
Identify by its dark color, heavy weight compared to other rocks of the same size, and fine-grained texture. Commonly found in volcanic fields, oceanic islands (like Hawaii), and mid-ocean ridges.
