igneous
Basalt Pebble
Basalt
Hardness: 6-7 on Mohs scale; Color: Dark grey to black; Luster: Dull/Sub-metallic; Crystal Structure: Aphanitic (fine-grained); Specific Gravity: 2.8–3.0. Smooth, rounded texture due to water erosion.
- Hardness
- 6-7 on Mohs scale
- Color
- Dark grey to black
- Luster
- Dull/Sub-metallic
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Physical properties
Hardness: 6-7 on Mohs scale; Color: Dark grey to black; Luster: Dull/Sub-metallic; Crystal Structure: Aphanitic (fine-grained); Specific Gravity: 2.8–3.0. Smooth, rounded texture due to water erosion.
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 has been further shaped by river or coastal wave action over thousands of years.
Uses & applications
Used in construction as a base for roads, as concrete aggregate, and for railroad ballast. High-quality smooth pebbles are used in landscaping and hot stone massage therapy.
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 dark color, heavy weight for its size (high density), and lack of visible crystals to the naked eye. Commonly found on beaches or in riverbeds near volcanic regions.
