See :
Crystal structure of tetrabasic lead sulfate (4PbO-PbSO4). An intermediate
phase in the production of lead-acid batteries.
I.M. Steele and J.J. Pluth
J. Electrochem. Soc. 145 (1998) 528-533.
Of course, not yet in ICSD. Best wishes,
Armel Le Bail - Université du Maine, Laboratoire des Fluorures,
CNRS ESA 6010, Av. O. Messiaen, 72085 Le Mans Cedex 9, France
http://fluo.univ-lemans.fr:8001/
http://www.cybercable.tm.fr/~cristal/