Fulgurite
The fulgurite (from the Latin fulgur, 'lightning') is a tube-shaped metamorphic rock composed of lechatelierite (vitrified silica) that It can be found in sand or sandstone. Its formation is due to the fall of atmospheric rays.
Etymology
The name "fulgurite" comes from the Latin "fulgur", which means "lightning".
Training
The high temperature caused by lightning striking a sandy ground causes the fusion of silica grains, as it can reach 4,000 degrees Celsius, up to a depth of more than one meter, but in an area very narrow. The silica is thus vitrified in the form of ray tubes, from 2 to 50 mm in diameter, sometimes twisted or branched. Such fulgurites can be found in sandy deserts and in coastal dunes.
They can be different colors depending on the composition of the sand in which they formed, including black, bronze, green, and translucent white. The interior of fulgurite is commonly smooth or outlined with fine bubbles; the exterior is generally covered with rough particles of sand. They have a rootlike appearance and often show small holes. Fulgurites sometimes form glassy ensembles in solid rock.
The formation of fulgurites is a rare phenomenon, and extracting a complete one is complicated due to the brittleness of the mineral, which breaks easily.