Basalt is an extrusive igneous rock. It was formed as basaltic lava flow exposed and cooled on the surface of the planet. It is the most common volcanic rock on the Earth and on the other planets.
The phenocrysts include plagioclase, clinopyroxene, calcic plagioclase, and sometimes olivine and orthopyroxene. The groundmass contains the same minerals (non-olivine), magnetite and quartz. Usually, basalts are dark gray, black or greenish-black rock. Basalt is used as a raw material for the production of basalt fiber.