igneous
Basalt Pebble
Basalt
Hardness: 6 on Mohs scale. Color: Dark gray to black, often weathering to brownish tones. Luster: Dull or earthy. Structure: Fine-grained (Aphanitic) to microscopic. Cleavage: None. Specific Gravity: 2.8–3.0.
- Hardness
- 6 on Mohs scale
- Color
- Dark gray to black, often weathering to brownish tones
- Luster
- Dull or earthy
Identified More igneous →
Explore Basalt Pebble in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6 on Mohs scale. Color: Dark gray to black, often weathering to brownish tones. Luster: Dull or earthy. Structure: Fine-grained (Aphanitic) to microscopic. Cleavage: None. Specific Gravity: 2.8–3.0.
Formation & geological history
Formed from the rapid cooling of magnesium-rich and iron-rich lava at or near the Earth's surface. This specimen appears to be water-worn, indicating it was shaped by fluvial or coastal processes.
Uses & applications
Crushed basalt is used as aggregate in construction, road base, and railroad ballast. It is also used in cast basalt for abrasion-resistant liners and occasionally in stone masonry.
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 on the Moon, Mars, and Venus.
Field identification & locations
Identify in the field by its dark color, heavy weight (density), and fine-grained texture. It is often found in volcanic regions or as rounded pebbles in rivers and beaches.
