mineraloid / sedimentary (secondary formation)

Fulgurite

Fulgurite (Lechatelierite-rich fused silica)

Hardness: 6.5 (but very fragile); Color: Tan, gray, or white exterior with a glassy interior; Luster: Vitreous/Glassy inside, earthy outside; Structure: Hollow tube; Specific Gravity: 2.1-2.2

Hardness: 6
Color: Tan, gray, or white exterior with a glassy interior
Luster: Vitreous/Glassy inside, earthy outside

Identified March 9, 2026More mineraloid / sedimentary (secondary formation) →

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Physical properties

Hardness: 6.5 (but very fragile); Color: Tan, gray, or white exterior with a glassy interior; Luster: Vitreous/Glassy inside, earthy outside; Structure: Hollow tube; Specific Gravity: 2.1-2.2

Formation & geological history

Formed when lightning strikes sand or soil, instantly melting the silica at temperatures exceeding 1,800°C (3,270°F) to form a glass tube. Most are found in deserts or coastal dunes.

Uses & applications

Used primarily for scientific research on past weather patterns and as high-interest geological specimens for collectors and educational kits.

Geological facts

Also known as 'petrified lightning.' The interior is lined with Lechatelierite, a rare mineraloid of pure silica glass that does not occur in standard volcanic processes.

Field identification & locations

Identify by its unique hollow, tubular, or 'root-like' shape and the presence of fused sand grains on the outer surface. Frequently found in the Sahara Desert or the sand dunes of Florida.

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