This specimen shows numerous lustrous, parallel-growing cylindrite crystals (Pb₃Sn₄FeSb₂S₁₄). It is accompanied by lighter gray acicular of incaite, a tin-rich Sn(II) franckeite variety (Pb,Ag)₄Sn₄FeSb₂S₁₅, which grow interlaced in the cylindrite. It is from the type locality for both species. 6z3y4q

This is a rich and a huge size 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 mine at Poopo is the type locality for the species. A museum specimen.