igneous
Vesicular Basalt
Basalt (Mafic volcanic rock)
Hardness: 5-6 Mohs. Color: Dark gray to black, often weathering to brown or reddish. Luster: Dull/Earthy. Structure: Massive with many small cavities (vesicles). Specific Gravity: 2.8-3.0.
- Hardness
- 5-6 Mohs
- Color
- Dark gray to black, often weathering to brown or reddish
- Luster
- Dull/Earthy
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Physical properties
Hardness: 5-6 Mohs. Color: Dark gray to black, often weathering to brown or reddish. Luster: Dull/Earthy. Structure: Massive with many small cavities (vesicles). Specific Gravity: 2.8-3.0.
Formation & geological history
Formed from the rapid cooling of magnesium-rich and iron-rich lava at the Earth's surface. The holes (vesicles) are created by gas bubbles trapped in the lava as it solidifies. Can be found in volcanic fields of various ages.
Uses & applications
Used as aggregate in construction, road base, decor for aquariums or landscaping, and occasionally as a source of industrial minerals.
Geological facts
Basalt is the most common rock type on Earth's crust and also covers large areas of the Moon, Mars, and Venus. On the Moon, the dark plains known as maria are composed of basalt.
Field identification & locations
Identify by its dark color, heavy weight (relative to size), and characteristic pitted or 'bubbly' surface texture. Commonly found in tectonic plate boundaries and hotspots like Hawaii or Iceland.
