Basalt Pebble

Hardness of 6 on the Mohs scale; dark green to black color; fine-grained, aphanitic texture; dull to sub-vitreous luster; specific gravity around 2.8-3.0.

Formed from the rapid cooling of low-viscosity lava rich in iron and magnesium exposed at or very near the Earth's surface, often shaped into a smooth pebble by water action in rivers or beaches.

Used in construction as aggregate, dimension stone, in landscaping, and occasionally polished for decorative items.

Basalt is the most common rock type in the Earth's crust underlying the world's ocean basins and also forms much of the volcanic crust on other terrestrial planets like Mars and Venus.

Found worldwide in volcanic regions and riverbeds; identified by its dark color, heavy weight for its size, and fine-grained texture.