Basalt

Hardness of 6 on the Mohs scale, dark gray to black in color, fine-grained to aphanitic texture, dull luster, composed mostly of plagioclase feldspar and pyroxene.

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, often associated with volcanic activity and basaltic plateaus.

Used in construction, aggregate for roads, production of rock wool insulation, and manufacturing tiles or countertops.

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

Can be identified in the field by its dark color, heavy weight, and fine-grained texture lacking visible crystals without a microscope.