The crystals of Potosiite on this specimen are certainly among the largest in the world. This piece is from the great find of 2004. This specimen is a very attractive, very rare, superb, crystallized specimen of Potosiite consisting of several, extremely rare, highly lustrous, heavily striated, tabular blades - some are twinned - and two of which measure 17 mm and 15 mm sitting atop crystallized and the equally rare triclinic lead, tin, iron, antimony sulfosalt Franckeite. The crystals of Potosiite on this specimen are exceptionally large. Before these new specimens were discovered, some of the largest known crystals of Potosiite were massive, uncrystallized granules less than 1 mm in most cases. This find completely redefined Potosiite.