metamorphic
Fulgurite
Fulgurite (Lechatelierite)
Hardness: 6.5-7 (brittle), Color: Black, brown, or gray with fused sand, Luster: Vitreous to dull, Crystal Structure: Amorphous (glassy), Cleavage: None, Specific Gravity: 2.1-2.2
- Hardness
- 6
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Physical properties
Hardness: 6.5-7 (brittle), Color: Black, brown, or gray with fused sand, Luster: Vitreous to dull, Crystal Structure: Amorphous (glassy), Cleavage: None, Specific Gravity: 2.1-2.2
Formation & geological history
Formed when a cloud-to-ground lightning strike discharges into sand or soil, instantly melting the silica at temperatures exceeding 1,800 °C (3,270 °F) to form hollow, glass-lined tubes.
Uses & applications
Used primarily as collector's specimens, in unique jewelry settings, and for scientific research into ancient atmospheric conditions.
Geological facts
Fulgurites are often called 'petrified lightning.' They are technically a variety of lechatelierite, which is a rare mineraloid formed by high-energy events.
Field identification & locations
Identified by their hollow tube shape and rough outer surface covered in sand grains. Common in deserts or lightning-prone beaches. Use a brush to clear sand; they are very fragile.
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