Fadenquartz

This variety of quartz was formed between two slowly opening fissure walls. This process caused fine cracks in the growing quartz, which immediately filled up again with hydrothermal solution. Such a crack healed quickly, but left a fine trace of fluid inclusions which can be perceived as a whitish stripe or «thread» (=Faden in German).

Photo: Gauligletscher BE, collection Felix Spahr; not for sale.