This paper presents results of a complex mineralogical study of the rare uranyl carbonate of lead, that was found in Příbram, Central Bohemia, Czech Republic (Jánská vein, Březové Hory deposit). Widenmannite represents an important alteration product of uraninite on the vein and was found in a few different associations.
The dating of this mineral involving alpha spectroscopy and Pb isotopes is presented.