igneous
River Stone (Basalt)
Basalt
Hardness: 6 (Mohs); Color: dark gray to black; Luster: dull to matte; Crystal structure: aphanitic (fine-grained); Cleavage: none; Specific gravity: 2.8-3.0
- Hardness
- 6 (Mohs)
- Color
- dark gray to black
- Luster
- dull to matte
Identified More igneous →
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Physical properties
Hardness: 6 (Mohs); Color: dark gray to black; Luster: dull to matte; Crystal structure: aphanitic (fine-grained); Cleavage: none; Specific gravity: 2.8-3.0
Formation & geological history
Formed from the rapid cooling of magnesium-rich and iron-rich lava. This particular specimen has been mechanically weathered and smoothed by water transport in a river or coastal environment.
Uses & applications
Used in construction as aggregate, in landscaping, as massage stones (due to heat retention), and as decorative elements in gardens or aquariums.
Geological facts
Basalt is the most common volcanic rock on Earth and also makes up most of the ocean floor. It is found on the Moon and Mars as well.
Field identification & locations
Identify by its dark color, heavy weight for its size, and absence of visible crystals. It is commonly found in riverbeds, along beaches, and near volcanic regions worldwide.
