igneous
Fulgarite
Fulgurite (Lechatelierite / Vitrified Sand)
Hardness: 5.5 to 7 on the Mohs scale (due to fused silica); Color: Dark brown, black, grey, or white depending on impurities; Luster: Glassy to vitreous; Crystal structure: Amorphous (glassy, non-crystalline); Specific gravity: ~2.2
- Hardness
- 5
- Color
- Dark brown, black, grey, or white depending on impurities
- Luster
- Glassy to vitreous
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Physical properties
Hardness: 5.5 to 7 on the Mohs scale (due to fused silica); Color: Dark brown, black, grey, or white depending on impurities; Luster: Glassy to vitreous; Crystal structure: Amorphous (glassy, non-crystalline); Specific gravity: ~2.2
Formation & geological history
Formed in seconds when a high-voltage lightning strike (typically >100,000 amperes) hits sandy soil or rock, instantly melting and fusing the material at temperatures exceeding 1,500 to 2,000 degrees Celsius.
Uses & applications
Collected as a unique geological specimen, used in scientific research regarding paleoclimates and ancient atmospheric conditions, and occasionally made into jewelry.
Geological facts
Commonly known as 'fossilized lightning', fulgurites preserve hollow tubes where vaporized steam and gases expanded during the lightning strike. They are fragile and often found broken in fragments.
Field identification & locations
Found in sandy deserts, beaches, or mountain peaks prone to frequent thunderstorms. Look for glassy, tubular crusts mixed with fused sand grains protruding from the ground.
