Their formation requires a dry dielectric overlying a more conducting soil layer, and their interior may feature blister-like bubbles and roots, while their exterior is usually composed of coarse sand particles.
The first recorded discovery of one was made by Pastor David Hermann in Germany in 1706, but they were later described by Hentzen and Barrows. The groundwater table puts a downward limit on their formation, and they generally come in two types; the most rare is the rock variety which are almost exclusively found on mountain peaks. One composed of staurolite, ilmenite, and rutile was discovered at Camp Blanding, and African ones often contain Lechatelier-ite. Their formation requires a dry dielectric overlying a more conducting soil layer, and their interior may feature blister-like bubbles and roots, while their exterior is usually composed of coarse sand particles. FTP, name these rare geological formations, hollow glass tubes created by the super-heating of sand when it is struck by lightning.
The first recorded discovery of one was made by Pastor David Hermann in Germany in 1706, but they were later described by Hentzen and Barrows.
fulgurites (or fulqurites)