mineral

Fulgurite

Lechatelierite (Silica Glass)

Hardness of 5.5 to 6 on the Mohs scale, typically gray, brown, or black, glassy to dull luster, amorphous crystal structure, brittle with conchoidal fracture.

Identified August 1, 2026More mineral →

Explore Fulgurite in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Hardness of 5.5 to 6 on the Mohs scale, typically gray, brown, or black, glassy to dull luster, amorphous crystal structure, brittle with conchoidal fracture.

Formation & geological history

Formed when lightning strikes sand or soil, fusing the silica together at extremely high temperatures (over 1,800 degrees Celsius) in a matter of seconds.

Uses & applications

Prized by mineral collectors, used in scientific research regarding ancient atmospheric conditions and lightning strikes.

Geological facts

Fulgurites are often called 'fossilized lightning'. They can form deep, branching tubes underground tracing the path of the electrical discharge.

Field identification & locations

Found in sandy deserts, beaches, and high-altitude mountain peaks where lightning strikes are frequent. Identified by its hollow, glassy tubular structure and fused sand grains.