Sunday, October 17, 2021


 Note: This is a published translation for educational purposes and may contain errors or be inaccurate.

 A single lightning bolt can deliver 5 gigajoule of enough energy to power an average American household for more than a month.  When powerful lightning strikes a sandy area such as a beach or dune, sand particles can melt and fuse in less than a second. 

Sand melts at around 1800 degrees Celsius, but the temperature in a beam of light can reach 30,000 degrees, or more than five times the temperature on the surface of the sun.  If conditions are right, the sand forms long hollow tubes called fulgurite.  The term comes from the Latin word fulgur, which means "lightning".  Although lightning strikes from the earth at least a million times each day, it only rarely does form fulgurites.

 Fulgurites are usually found under the surface of the sand, generally decreasing in diameter and sometimes branching outs as they descend.  Its shape reflects that the path ray took as dispersed on the ground.  Because of this, fulgurites are called "fossilized lightning".

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

 Fulgurites look like roots due to their branching and have a rough surface, covered with partially melted grains of sand.  But the internal surfaces are generally smooth and glassy due to quick cooling and solidification of the sand.  The size and length of a fulgurite varies with the strength of the ray and the thickness of the sand bed.  Many sand fulgurites average one or two inches in diameter and can be up to 30 inches long, but fulgurites as long as 16 feet have been found.  Some fulgurites can penetrate deep into the ground, sometimes occurring up to 49 feet below the surface that was struck.

 Fulgurites can also form when lightning strikes rock, occurring as coatings or crusting of glass, and sometimes as veins on the rock surface, preexisting lining fractures within the host rock.

 Fulgurites have been described as early as 1711 and are found all over the world, from mountain peaks to the Sahara desert, but are considered rare.  They are not precious but are appreciated by many for their scientific value.  By studying the distribution of fulgurites over a specific area, for example, one can deduce the occurrence of storm activity in the area during a given period, which in turn can help to understand past climates.  250-million-year-old fulgurites found in the Sahara have shown, or rather confirmed, that the desert was once a fertile region where rainstorms were common.


 1- The fulgurite is a type of mineral formation that occurs when the lightning strikes the sand.

 2 - 3- 6.5" fulgurite coated hollow sand from the Sahara Desert in Boujdour Province. Photo Credit

 4- Close the hollow opening in the previous sample.  Photo credit

 5- Fulgurite sands of Algeria.  On display at the San Diego County Fair, California, USA.  Photo credit

 6- Fulgurite found in the Mauritanian desert.  Photo credit

 7- Fulgurite found in the Libyan desert, in Egypt.  Photo credit

 8- This image is often posted on social media sites as an example of a flare.  It's actually a sculpture (trunks covered with sand) created by "Sandcastle Matt".  You can see his work on your Flickr stream.

 9- Another falsely captioned image.  Fulgurites form below the surface, embedded in the sand and only appear above it if the sand has eroded around them.  Also, as the Hoaxes Museum rightly observes, "a flare of this size would be extremely valuable and would likely have already been carted away to a museum. It wouldn't be sitting on a beach surrounded by vacation goers, any of whom could potentially break it. it."


 Sources: Wikipedia / Minresco / Utah Geological Survey / Fossilized Lightning by Jeff J. Person

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