THE CRYSTAL-STRUCTURE OF MOCTEZUMITE [PBUO2](TEO3)2

Moctezumite, [PbUO2](TeO3)2, is monoclinic, P2(1)/c, with a = 7.813(5) , b = 7.061(2), c = 13.775(4) angstrom, beta = 93.71(2)-degrees, and Z = 4. Its structure has been refined to an unweighted residual of 0.04 1 using 1440 reflections. Moctezumite possesses a layer structure para llel to (001). In each layer, U-coordination pentagonal bipyramids for m zigzag chains parallel to b by sharing edges. The U chains alternate with chains of Pb edge-sharing monocapped trigonal-prism coordination polyhedra. The U-Pb layers stacked along c are connected by Te2O6 un its. Each Te2O6 unit is composed of TeO3psi and TeO4psi (psi = lone pa ir), which share an 0 atom. The structure of moctezumite consists of s lightly modified schmitterite-like (UTeO5) winged U polyhedral chains separated by Pb polyhedral chains.