Few of nature’s elemental phenomena are more powerful yet less permanent than lightning… well, not exactly. Fulgurites, or “petrified lightning”, are the glassy trails of lightning strikes left in sandy soil or exposed rocks. As fragile as they are beautiful, fulgurites are the next best thing to holding a lightning bolt in your hand!
Out Of The Blue, Into The Ground
The word fulgurite is derived from “fulgur”, which means “thunderbolt” in Latin. That’s just part of the story, though, as the real action begins once the bolt hits the ground. The average lightning bolt packs up to a gigajoule of energy – enough to power an all-electric home for about a week, or around 300 kilowatt-hours. When a strike enters the ground it makes its presence known by vaporizing soil & sand along a downward, branching path that may be up to 20 feet long. Temperatures of up to 50,000 degrees blast sand (silicon dioxide) into a hollow tube lined with what is essentially glass: a fulgurite.
It’s estimated that around 16 million lightning storms occur on our planet each year, with most of these storms shedding multiple lightning bolts. Though conditions have to be just right for a fulgurite to form, the sheer number of bolts hitting sandy soil over countless centuries has resulted in innumerable fulgurites (or pieces thereof) scattered in and on the ground.
Fossilized Lightning
Archaeologists working near Corrie Village on the cost of Scotland’s Isle of Arrran in 1966 made an astonishing discovery: a fossilized fulgurite! Judging from the age and nature of the surrounding sandstone, the lightning strike which created the fossil fulgurite occurred some 250 million years ago at the end of the Permian Period. Though our planet has changed much since that ancient era before the dinosaurs even appeared, the fundamental physical processes that drive the hydrological cycle, including lightning, obviously have not.
The Corrie Village fulgurite fossil was likely formed when lightning struck the crest of a sand dune and radiated into the dune, vitrifying and hollowing out a glass tube of unknown length and depth. Deserts in Scotland? A quarter of a billion years ago, what is now the British Isles existed as part of Pangaea, a huge super-continent with vast, desert-like interior regions.
Mother Nature’s Litter Box
The easiest fulgurites to fond and recover are those that have formed recently in loosely structured sand. The shifting sand makes the fulgurites both easy to see and relatively uncomplicated to remove. One might compare the occurrence of fulgurites in dune fields to a cat’s litter box, except on a much larger scale.
Expanded human activity in previously isolated desert regions such as the Sahara and Gobi deserts, and the Australian Outback, has helped make fulgurites less rare for collectors to acquire and at the same time, lowered their cost.
Lechatelierite, or “Lightning Glass”
The glossy, glassy interior lining of many fulgurites is actually a form of natural glass called Lechatelierite. In some cases the tube may be completely plugged with glass. People have worked Lechatelierite into jewelry since prehistoric times and it can be quite beautiful as the examples above right clearly show.
It’s possible that ancient societies noted the connection between lightning, sand, and the glass inside fulgurites; then set about artificially melting sand to make the first glass.
Man-Made Fulgurites, Part 1
In early May of 2006, something odd caught the eye of a pedestrian making his way along the concrete sidewalk past the corner of Colfax and 24th in Minneapolis, Minnesota. According to the discoverer, “The scar was something like 3 meters long and in about 5 segments, each about 2 cm deep and up to about 5 cm wide… On closer examination, I found the edges of the scar almost completely encrusted with black glass, some of which was easy to pick loose.”
Though the characteristics of the scar have much in common with those of classic fulgurites, the horizontal structure of the scar and its location directly beneath power lines hint at a more prosaic yet still electrical origin.
Man-Made Fulgurites, Part 2
Downed power lines are one thing; artificially triggering lightning to make DIY fulgurites is another thing entirely. That’s exactly what artist Allan McCollum has done, however, not one but some hundreds of times in the summer of 1997. The results range from slim glass tubes no larger than soda straws to the Mother Of All Fulgurites, a fork-tailed monster over 17 feet deep that the Guinness World Book of Records has recognized as the world’s longest.
McCollum conducted his fulgurite experiments in cooperation with the University of Florida’s International Center for Lightning Research and Testing and their base of operations was at the Camp Blanding national guard base near Starke, Florida. During what was referred to as The Event, lightning was attracted by way of small rockets launched two to three thousand feet into overhead storm clouds – with each rocket spooling out an ultra-thin copper wire that kept it grounded and directed any provoked lightning. Ben Franklin would be proud!
Other Glass Acts
Besides lightning strikes, there are a couple of other ways to create glass from sand. Both methods involved the application of extreme force resulting in exceptionally high temperatures. The first is a meteorite impact, such as the one that created the Kebira Crater on the Libya-Egypt border nearly 30 million years ago. A huge area was showered with melted sand, which when cooled took on an ethereal yellow-green hue. So-called Libyan desert glass was prized by the ancient Egyptians, and a worked piece is prominently displayed in the center of an ornate breastplate designed for King Tut.
Glass can also be created by ground or near-ground level atomic explosions. The first such atomic bomb explosion took place on July 16, 1945 at the White Sands Proving Ground near Alamogordo, New Mexico. Known as “Trinity”, the test measured 20 kilotons and left a large area at Ground Zero covered with greenish glass. Dubbed “Trinitite”, the glass was (and still is) mildly radioactive yet is much coveted by collectors and souvenir hunters.
One Strike, You’re Out
Meteorites, atomic blasts… suddenly lightning bolts are looking a lot better, though you still don’t want to be too close when one arcs down from the sky. The somewhat sphincter-ish impact spot above shows where lightning struck the ground – beneath the center there’s likely a fulgurite. Taking the anatomical analogy slightly further and to take this article to its logical “end”, here’s a video of some Fulgurite Endoscopy:
Fulgurite Endoscopy, via Cleanmonk



