Summary: Mukherjee's definition of psilomelane, A₃X₆Mn₈O₁₆ of orthorhombic symmetry with the space group P222 and the dimensions determined for a single crystal of the Schneeberg sample, is found true for the psilomelane from Ratanpur, India. The indexing of powder data of the Ratanpur sample with the orthorhombic axes a 9·45, b 13·90, c 5·72 Å is most satisfactory.