A single bolt of lightning can deliver 5 gigajoule of energy enough to power an average U.S. household for more than a month. When such a powerful lightning bolt strikes a sandy area like a beach or a dune, the sand particles can melt and fuse together in less than a second. Sand melts at about 1800 degrees Celsius, but the temperature in a bolt of lighting can reach 30,000 degrees, or more than five times the temperature on the surface of the sun. If conditions are right, the fused sand forms long hollow tubes called fulgurite. The term comes from the Latin word fulgur, which means "lightning". Although lightning strikes earth at least a million times each day, only rarely does fulgurites form.

Fulgurites are usually found beneath the surface of the sand, generally decreasing in diameter and sometimes branching outs as they descend. Their shape reflects the path lightning bolt took as it dispersed into the ground. Because of this, fulgurites are sometimes called “fossilized lightning”.

A 14 inch fulgurite found near Queen Creek, Arizona. Photo credit