cotype locality). At the Kremnica deposit argentopolybasite was found as discrete, well-developed (pseudo)hexagonal tabular crystals up to 4 mm in size or as complex crystalline aggregates and groups up to 5 mm in size in cavities of quartz. It is associated with pyrargyrite, polybasite, stephanite, miargyrite, rozhdestvenskayaite-(Zn), argentotetrahedrite-(Zn), naumannite, gold and pyrite.Argentopolybasite is dark grey to black, with a black streak and metallic to opaque lustre. The Mohs hardness is about 3. It is brittle without any observable cleavage and with a conchoidal fracture. The calculated density is 6.403 g•cm -3 . In reflected light, argentopolybasite is grey, without any observable bireflectance and very weak pleochroism. It shows moderate anisotropy in crossed polarisers with weak greenish and green-blue tints. The reflectance values for wavelengths recommended by the Commission on Ore Mineralogy of the IMA are