Bourge-St-Pierre - Fulgurite

Bourg-St-Pierre Fulgurite is a lightning-formed natural glass from the Bourg-St-Pierre area of Switzerland. Fulgurites form when lightning strikes silica-rich ground, instantly melting and fusing sand, soil, or rock along the path of the electrical discharge. Although entirely terrestrial in origin, they sit naturally alongside Impactites, Tektites, Obsidian, and other natural glasses because they record a sudden high-energy event preserved in glass.

Bourg-St-Pierre Fulgurite specimens can vary in shape and texture, but Fulgurites commonly form hollow, branching, root-like, or irregular glassy structures. Their outer surfaces are often rough, granular, and partly fused with surrounding sediment, while interiors may be smoother, glassier, vesicular, or lined with small bubbles. Colour and composition depend on the material struck by the lightning, making each specimen highly individual. General descriptions of Fulgurite note that they are natural silica-rich glass formed by lightning striking and melting sand or bare rock.

Studying Fulgurites provides insight into lightning strike processes, rapid melting, glass formation, and extreme temperature events at Earth’s surface. For collectors, Bourg-St-Pierre Fulgurite offers an unusual European example of ‘fossilised lightning’, with strong natural history appeal and a direct connection to one of the most powerful atmospheric processes on Earth. Each specimen represents a brief but intense event, preserved as natural glass.