Franckeite is one of the rarest sulfosalts in the world. This specimen is a very rich, incredibly rare, superb quality, crystallized specimen of the triclinic lead, tin, iron, antimony sulfosalt Franckeite consisting of somewhat "sword"-shaped crystals oriented into spherical aggregates. The piece is associated with grey, metallic Galena crystals and one small, but very rare crystal of Potosiite, which is the small "curved" crystal in the close-up photo below. This piece is a great small cabinet specimen for somebody looking to own a very rare and displayable mineral specimen. A good opportunity to acquire something that is rarely offered in the open market for a great price. Franckeite and Potosiite belong to the only group of minerals that forms in naturally "round" or "cylindrical" shaped crystals. This specimen is over 30 years old and was part of the best find of the material. There were only a handful of good specimens, and well crystallized display pieces like this are few and far between. Ex. Brian Kosnar.