Cylindrite is an uncommon lead, tin, antimony, iron and tin sulfide. What makes it really amazing to look at is that it is the ONLY naturally occurring mineral species with CYLINDRICAL crystals! This specimen is from the type locality at Poopo, Bolivia. Massive dark gray ore hosts splendent, diverging, dark gray crystals of cylindrite, to 4.3 cm in length. These are of quite good size for the species, and it is a very rich piece