Basalt is a volcanic igneous rock formed by the rapid cooling of lava.With a name derived from Latin for "very hard stone," basalt is actually an extremely hard black igneous rock found throughout the Earth and our solar system. It can be found not only on Earth, but also on the Earth's moon and Mars. It is a volcanic igneous rock, formed from lava that cools rapidly at the Earth's surface. It is generally black in color due to the high amounts of magnesium oxide and calcium oxide, and very low amounts of the light-colored silicate minerals. It has many industrial applications, including as building materials and heat insulators.