Basalt

Hardness of 6 on the Mohs scale, dark gray to black in color, fine-grained aphanitic texture, dull luster, high specific gravity.

Formed from the rapid cooling of low-viscosity lava rich in magnesium and iron exposed at or very near the surface of a planet or moon.

Used extensively in construction as crushed aggregate for road bases, concrete production, and railway ballast, as well as in stonemasonry.

Basalt is the most common rock type in the Earth's crust underlying the ocean basins, and it is also commonly found on the Moon and Mars.

Identified by its dark color, fine-grained texture, and high density. Found worldwide in volcanic regions, oceanic crusts, and ancient flood basalt provinces.