Lightning makes glass - ever wondered how?

Lightning makes glass – ever wondered how?

I love glass. No, make that I really love glass. I don’t just love the glass I make, I love all types and standards and modes of glass. I love its colours, what you can do with it – even discovering what you can’t do with it!



I was wandering round the internet and came across these interesting facts about lightning and glass.



Nature created glass long before man figured out how to craft glass. You probably know that when lightning strikes sand, the heat sometimes fuses the sand into long, slender glass tubes called fulgurites.




“Fulgurites” (from the Latin Fulgur meaning “Lightening”) are formations created when grains of sand are fused together by extreme heat to echo the shape of the lightning bolt.

Some people even believe that Fulgurites are so otherworldy that they help answer their prayers.

The geologists among our readers will already know that fulgurites are classified generically as a variety of the “mineraloid lechatelierite”.  Interestingly, their absolute chemical composition changes depending on the physical and chemical properties of the material that the lightning struck.


Fulgurite from Iwamizawa Park, Japan

Fulgurite from Iwamizawa Park, Japan


Mostly they are hollow as you can see in the image above.  The protocrystalline and heterogeneously-microcrystalline tubes that form during the lightning strike propogate into silica-rich quartzose sand, mixed soil, clay, caliche and other carbonate-rich sediments, humic sediments, conductive biomass  such as peat, water-saturated wood, or even dung), or some other anthropogenic materials.  Colloquially, they are been referred to as petrified lightning.




Fulgurites can exceed 8 metres in length, but they are almost impossible to recover completely in tact as they are extremely fragile. Usually they are found in pieces that are around 15cms in length and 5 to 20mm in diameter.
When lightning strikes rock (and not sand) it creates different shapes.


row of fulgurite specimens $100 each
When lightning strikes, it is believed that each flash releases an average energy of 1 billion Joules. Air temperatures may momentarily reach 10,000 degrees K, even sometimes 30,000 degrees K.
The peak currents measured range from 10kA to 100kA but they last only a few microseconds.



This high energy will melt or vaporize the sands or the rocks with formations of amorphous glass which were named by mineralogist and geologist Antoine Francois Alfred Lacroix (1863-1948) who studied this phenomenon.


fulgurites from Arizona


Fulgurites found at the feet of the sand dunes in South West Egypt in the “Great Sand Sea” are actually on sale with specimens of .85″ to 1.24″, I think on Ebay, for about $100.00 each; some from Arizona are for sale as well if you are interested.


fulgurites 1

You can find fulgurite jewellery all over the internet.  Here’s an example of a fulgurite necklace.  I don’t know how fragile it is, or how genuine but thought I’d share with you what I discovered.

For sale on Etsy Shop called Rootiebirds for $208.70

For sale on Etsy Shop called Rootiebirds for $208.70

Did you find these weird and wonderful facts as interesting as I did? I do hope so, and that you enjoy the rest of the website and other blogs as they come alone. Comments are welcome.

Thank you for reading.






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