Franckeite (Var: Potosiite), Franckeite
San Jose Mine, Oruro City, Cercado Province, Oruro Department, Bolivia
Miniature, 4.3 x 3.2 x 2.3 cm
The crystals of Potosiite on this specimen have to be 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 - measuring up to 9 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. I have been told that the part of the mine that produced these specimens is now mined out and will most likely never produce these impressive specimens again.