mineral
Fulgurite
Lechatelierite (vitreous silica / silica glass)
Hardness: 5.5 to 6.5 on the Mohs scale, Color: Brown, tan, grey, or white with a rough, sandy exterior and a glassy interior, Luster: Vitreous (glassy) on the inside, dull or earthy on the outside, Crystal Structure: Amorphous (glass), Cleavage: None (conchoidal fracture), Specific Gravity: 2.1 to 2.2
- Hardness
- 5
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Physical properties
Hardness: 5.5 to 6.5 on the Mohs scale, Color: Brown, tan, grey, or white with a rough, sandy exterior and a glassy interior, Luster: Vitreous (glassy) on the inside, dull or earthy on the outside, Crystal Structure: Amorphous (glass), Cleavage: None (conchoidal fracture), Specific Gravity: 2.1 to 2.2
Formation & geological history
Formed when lightning strikes sand or soil, fusing and melting the silica grains together into a glass tube or mass within seconds at temperatures exceeding 1,800 degrees Celsius.
Uses & applications
Collected as unique natural specimens ('petrified lightning'), scientific research on ancient climates and lightning strikes, and sometimes used in jewelry or educational displays.
Geological facts
Fulgurites can sometimes reach several meters deep into the earth. They are exceptionally fragile and difficult to excavate completely intact.
Field identification & locations
Found in sandy deserts, beaches, and high-altitude mountain peaks where lightning frequently strikes. Identified by its hollow, glassy-lined interior channels and rough, sand-cemented exterior.
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