Metamorphic (Pseudo-igneous)

Fulonite (Fulgurite-like)

Fulgurite (SiO2 fused silica/lechatelierite)

Hardness: 6.5-7 (Mohs scale), Color: Dirty tan, grayish, or brownish surface with glassy interior, Luster: Vitreous/Glassy inside, earthy/sandy outside, Structure: Amorphous/Tubular, Cleavage: None (conchoidal fracture), Specific Gravity: 2.1-2.5

Hardness: 6

Identified March 18, 2026More metamorphic (pseudo-igneous) →

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Physical properties

Formation & geological history

Formed when lightning strikes sand, soil, or rock, instantly melting the silicate material at temperatures exceeding 1,800°C (3,270°F). These 'fossilized lightning' tubes are common in desert or beach environments and can be from any geological age from modern to millions of years old.

Uses & applications

Primarily used for scientific study of past lightning strikes, collector specimens, and occasionally in metaphysical jewelry. They have limited industrial use due to their fragile, porous nature.

Geological facts

Fulgurites are the rarest mineral-like structures on Earth formed by lightning. The longest fulgurite ever found was over 4.9 meters (16 feet) long in Florida.

Field identification & locations

Identify in the field by looking for hollow, glassy-lined tubes that resemble brittle, sandy twigs or roots. They are commonly found in the Sahara desert, Florida beaches, and the Gobi desert. For collectors: look for 'root-like' structures that feel lighter than regular stone.

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Staurolite (Fairy Stone)

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Staurolite (Fairy Cross)

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Biotite, K(Mg,Fe)3AlSi3O10(F,OH)2

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