Basalt Pebble

Hardness 6 on Mohs scale, dark gray to black color, earthy to dull luster, fine-grained aphanitic texture, specific gravity 2.8-3.0.

Formed from the rapid cooling of low-viscosity basaltic lava at or near the Earth's surface, subsequently rounded by water action in river or beach environments.

Used primarily in aggregate for concrete and asphalt road construction, railway ballast, and crushed stone.

Basalt is the most common rock type in the Earth's crust, forming most of the oceanic crust as well as major volcanic plateaus on land.

Identified by its dark color, heavy weight, and fine-grained matrix with smooth water-worn edges. Common in riverbeds, lakeshores, and oceanic beaches near volcanic geology.