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. This specimen is especially nice considering that it is loaded with crystals. The longest crystal measures 18 mm. The mine at Poopo is the type locality for the species. Incidentally, this species belongs to the only group of minerals that forms in naturally "round" or "cylindrical" shaped crystals.