St. Andreasberg, Harz Mountains, Lower Saxony, Germany
Small Cabinet, 6.5 x 4.2 x 3.0 cm
Apparently this was once studied carefully by somebody who knows a lot more than I do, and whom corrected its ID to this very rare mineral. Mindat confirms this is a valid species and notes: "This mineral is an intermediate member of a homologous series. The thickness of a galena sheet in the structure determines the series member. A very rare mineral." I cannot find a photo of material from Andreasberg but this specimen has crystals which, though tiny brilliant specks, look like the material I have seen from Pribram.