Using Lightning to Make Glass

Before the dawn of Science, a flash of lighting followed by thunder was considered to be the will of Greek Gods. Now that we know more about lightning, we know that it can be hotter than the surface of the Sun, that it can – contrary to popular belief – strike in the same place twice, and that when it hits sand, it can create some amazingly beautiful art.

Have you ever watched a film in which dramatic scenes of lightning are followed by the creation of glass? One such film is “Sweet Home Alabama”, where when lightning strikes sand, the quartz in the sand turns into a glass sculpture that resembles a plant root. Steel rods are rammed into the sand in order to provoke such a strike to take place.

Well, lightning strikes actually do fuse sand into cone or root-like structures, and this phenomenon is extremely rare. The resulting structures are known as “fulgurites”, meaning “thunderbolt stones”. They usually show branching or small holes.

HOW ARE FULGURITES FORMED BY LIGHTNING?

Fulgurites are formed when lightning with a temperature of at least 1800 °C instantly melts silica on a lightning conductor and fuses grains together. When cooled, the resultant product is a fulgurite tube. This entire process takes place over a mere duration of approximately

one second!

WHAT DO FULGURITES LOOK LIKE?

Fulgurites can be as thick as several centimetres in diameter and can have deep penetrations, sometimes as far as 15 metres below the surface that has been struck by lightning. One of the longest fulgurites that has been formed in modern days was found in Northern Florida, USA, and measures slightly longer than 4.9 metres. In the Yale University Peabody Museum of Natural History, you will find the longest known preserved fulgurite which measures approximately 4 metres in length. In his chronicle, “The Voyage of the Beagle”, Charles Darwin, the renowned explorer, recorded that fulgurite tubes that he had found in Drigg, Cumberland, UK, reached a length of 9.1 metres!