Fulgurite
Image: James St. John (CC BY 2.0)
Mineral NameFulgurite
Chemical FormulaSiO2
Mohs Hardness6
Crystal Systemamorphous
Lustervitreous
Streak Colorwhite
Cleavagenone
Fractureconchoidal
Specific Gravity2.2
Colorsreddish-brown, tan, off-white
Transparencyopaque
Type LocalitySahara Dune Field, Morocco
Mineral GroupNatural Glass (Silica-rich)
Usescollector, scientific study
Associated Mineralsquartz, cristobalite, tridymite
Rarityuncommon
Description
This specimen is a tubular to branching, reddish-brown to tan, vesicular mass with a rough, irregular surface, characteristic of a fulgurite.
Geological Context
Fulgurites are formed when lightning strikes the ground, melting silica-rich sand or soil into a natural glass (lechatelierite), often forming hollow, branching tubes.
