Basalt

Basalt is an aphanitic extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron exposed at or very near the surface of a rocky planet or moon.

Colors It Comes In - Dark Grey to Black and Dull Burgundy To Brown

Fracture - (1) Colonnade, (2) Entablature, (3) Horizontal fractures near flow tops, (4) Conchoidal

Shape - Variety Of Sizes, Column-Like, Hexagonal

Luster - Dull

Texture - Fine-grained, Aphanitic

Streak - White to Grey

Locality - In the USA, Basalt is widespread in Hawaii, Snake Plain River, and Columbia Basalt. Also, notable deposits occur in California, Minnesota, Texas, New England, and many other states.

Where It Can Be Found - Basalt is one of the most popular rock types, covering more than 70% of the Earth's surface. It forms in many places, including mid-ocean ridges, island arcs, ocean islands, rifting valleys, and back-arc basins.

Hardness On The Mohs Scale - 5 To 6 Out Of 10