igneous
Basalt Pebble
Basalt (Mafic volcanic rock)
Hardness: 5-6 (Mohs); Color: Dark grey to black; Luster: Dull or earthy; Structure: Aphanitic (fine-grained); Specific Gravity: 2.8-3.0
- Hardness
- 5-6 (Mohs)
- Color
- Dark grey to black
- Luster
- Dull or earthy
Identified More igneous →
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Physical properties
Hardness: 5-6 (Mohs); Color: Dark grey to black; Luster: Dull or earthy; 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. This specimen shows signs of water-worn weathering, suggesting it was found in a river or coastal environment.
Uses & applications
Primarily used in construction (crushed stone, railroad ballast) and as an industrial raw material for stone wool insulation.
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 and Mars.
Field identification & locations
Identify by its weight (dense for its size), dark color, and lack of visible crystals. Commonly found in volcanic regions, riverbeds, and along beaches.
