Basalts are the most prevalent and widely distributed of all igneous rocks. The vast majority of basalts are volcanic in origin, forming during the rapid cooling of lava on the Earth’s surface.

Basalts usually begin as a dark gray or black, but can develop a greenish or reddish crust when weathered. The grains of basalt are so fine that they cannot be distinguished without the help of a microscope. Under the sea, basalt flows are vast and are mostly found along oceanic ridges. Many islands in the oceans, such as Hawaii, are formed of layer upon layer of basalts erupted from underwater volcanoes. Extensive basalt flows can also be found in continental areas, often in the form of polygonal pillars that compose incredibly beautiful landscapes frequented by tourists.

Extremely durable and tough, basalts have been used for a variety of purposes by humans. Some of the earliest uses of basalts included the making of ax heads and vases. The Egyptians also utilized black basalt for sculptures and as a building material, primarily for paving stones. In modern times, basalts continue to be utilized for carvings and ornaments, appearing occasionally in polished form as jewelry. Other current uses of basalts include acting as durable floor tiles, as sturdy but flexible fabrics, and as an aggregate material in concrete.