  We report on the crystallographic structure of the layered compound
Pb3Mn7O15. Previous analysis based on laboratory X-ray data at room temperature
gave contradictory results in terms of the description of the unit cell.
Motivated by recent magnetic bulk measurements of this system, we
re-investigated the chemical structure with high-resolution synchrotron powder
diffraction at temperatures between 15 K and 295 K. Our results show that the
crystal structure of stoichiometric Pb3Mn7O15 has a pronounced 2-dimensional
character and can be described in the orthorhombic space group Pnma.
