metamorphic
Fulgurite
Fulgurite (Lechatelierite)
Rough, bulbous, or tube-like shape with a glassy interior and a crusty exterior of fused sand or soil grains. Hardness: 5.5 to 7. Color: Tan, white, or grey with pinkish inclusions. Luster: Vitreous inside, earthy outside.
- Hardness
- 5
- Color
- Tan, white, or grey with pinkish inclusions
- Luster
- Vitreous inside, earthy outside
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Physical properties
Rough, bulbous, or tube-like shape with a glassy interior and a crusty exterior of fused sand or soil grains. Hardness: 5.5 to 7. Color: Tan, white, or grey with pinkish inclusions. Luster: Vitreous inside, earthy outside.
Formation & geological history
Formed instantaneously when lightning strikes sand, soil, or rock, causing temperatures to briefly exceed 1,800°C (3,270°F) and melting the silica into a glass tube.
Uses & applications
Primarily collected by mineral enthusiasts, used in scientific research for studying paleo-lightning, and occasionally used in unique jewelry.
Geological facts
Fulgurites are often called 'petrified lightning.' They are extremely fragile and are usually found as hollow tubes that follow the path of the electrical discharge into the ground.
Field identification & locations
Look for elongated, root-like structures in sandy deserts or coastal dunes after lightning storms. They are often partially buried and are very light for their size due to their glassy, hollow nature.
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