Lechatelierite (Var.: fulgurite ) Locality: Great Sand Sea , Egypt ( Locality at mindat.org ) Size: 20.5 x 0.7 x 0.7 cm. A fulgurite is formed when lightning flashes into desert sand and literally melts the sand around the impact site into a glass cast following the shape of the electrical discharge. Obviously, large fulgurites, being thin-walled and elongated as they are, are fragile and hard to obtain. This is a fairly good-sized specimen, though, and from the classic locality for the material that I first was fascinated by as a kid, several decades ago now. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Lechatelierite
Natural silica glass — amorphous SiO₂ formed when lightning or meteorites fuse sand into fulgurites and tektites.
Intro adapted from Wikipedia (CC BY-SA).
Lechatelierite is an IMA-recognized mineral species in the silicate class, with the chemical formula SiO₂.
It crystallizes in the amorphous crystal system. It is a member of the Amorphous structural group.
IMA symbol Lch, IMA status: questionable, named in 1915.