Basalt River Stone

Hardness: 6-7 Mohs; Color: Dark grey to black; Luster: Dull/Matte; Crystal structure: Aphanitic (fine-grained); Specific gravity: 2.8-3.0.

Formed from the rapid cooling of magnesium-rich and iron-rich lava at the Earth's surface. This specific specimen has been worn smooth by water erosion in a river or beach environment over hundreds to thousands of years.

Commonly used in landscaping, aquarium decor, hot stone massage therapy, and as construction aggregate. Polished versions are used in decorative crafts.

Basalt is the most common rock type in the Earth's crust and makes up most of the ocean floor. It is also found extensively on the Moon and Mars.

Identify by its dark color, heavy weight for its size, and fine-grained texture. Commonly found in volcanic regions, riverbeds, and along coastlines.