Rock · Glass
Fulgurite
SiO2 glass (lechatelierite)
Fulgurites are tubes of fused sand formed when lightning strikes the ground, hollow with a glassy interior and sand-crusted outside, collected from the Sahara (Algeria, Libya), the Sand Hills of Nebraska and Florida beaches. They are fragile, rarely more than a few centimetres wide, and genuine ones are common enough to be affordable. The glass inside is lechatelierite, a mineraloid.
| Formula | SiO2 glass (lechatelierite) |
|---|---|
| IMA status | rock |
| Crystal system | Amorphous |
| Mohs hardness | 5–6 |
| Group | Glass |
| Type locality | None |
Fakes and treatments
'Fulgurites' made by burying sand around an electrical discharge or a hot rod are sold online; natural ones have irregular branching and sand adhering in a natural way.
Elsewhere
- Wikidata: Q924408
- Wikipedia: fulgurite
- Mindat: Fulgurite
Cite this article
Stratum Study. "Fulgurite" (Mineral). Stratum Study pack 2026.09, as of 2026-09-19. https://stratum.black/study/minerals/fulgurite. Accessed 2026-09-20.
@misc{stratum-fulgurite,
title = {Fulgurite},
author = {{Stratum Study}},
howpublished = {\url{https://stratum.black/study/minerals/fulgurite}},
year = {2026},
note = {Mineral article, Stratum Study pack 2026.09, as of 2026-09-19; sources: stratum, wikidata, commons. Accessed 2026-09-20.}
} Citations carry the pack version and the article's as-of date so they resolve to the same text later. The facts themselves belong to the sources listed below; cite those for the science.