Basalt River Pebble

Hardness: 6 (Mohs scale), Color: Dark grey to charcoal, Luster: Dull/Matte, Structure: Fine-grained aphanitic, Specific Gravity: 2.8-3.0.

Formed from the rapid cooling of magnesium-rich and iron-rich lava at or near the Earth's surface. This specific specimen has been smoothed and rounded by long-term water erosion in a river or coastal environment during the Holocene epoch.

Used in landscaping, as aquarium decor, or as a pocket stone. Industrial basalt is used for crushed stone in construction, road base, and railroad ballast.

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

Identify by its dark color, heavy weight for its size, and the lack of visible large crystals. Commonly found in riverbeds, glacial deposits, and along volcanic coastlines.