This is a rich of specimen of one of the most unique species in all the mineral kingdom. Cylindrite is a lead, iron, tin, antimony sulfosalt that forms in "cylinder" or "tube" shaped crystals, hence the name. In fact, this species belongs to the only group of minerals that naturally forms rounded, curved or tubular shaped crystals. This specimen is especially nice considering that it is loaded with crystals. The longest "cylinder" measures 17 mm. The mine at Poopo is the type locality for the species.