mineral

Fulgurite

Lechatelierite (Silica glass)

Mohs hardness of 5.5 to 6.5, color ranges from greyish-brown to black or tan, vitreous to dull luster, amorphous crystal structure (silica glass), no cleavage, specific gravity around 2.2.

Identified July 31, 2026More mineral →

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Physical properties

Mohs hardness of 5.5 to 6.5, color ranges from greyish-brown to black or tan, vitreous to dull luster, amorphous crystal structure (silica glass), no cleavage, specific gravity around 2.2.

Formation & geological history

Formed when a high-voltage lightning strike (typically >100,000 amperes) instantly melts and vitrifies loose sand or soil, occurring in desert or beach environments during thunderstorms.

Uses & applications

Used primarily as educational specimens, collector's items, and occasionally in scientific research to study ancient atmospheric conditions and lightning strikes.

Geological facts

Fulgurites are often called 'petrified lightning'. They can extend several meters deep into the ground depending on the path of the electrical discharge and moisture in the soil.

Field identification & locations

Found in sandy areas such as deserts and beaches where lightning frequently strikes. Identified by its tubular, glassy, or fused-sand structure often featuring hollow interior channels.