Quetzalcoatlite: A new octahedral-tetrahedral structure from a 2 x 2 x 40 [[micro]m.sup.3] crystal at the Advanced Photon Source-GSE-CARS Facility

The structure of quetzalcoatlite, [Zn.sub.6][Cu.sub.3][(Te[O.sub.3]).sub.2] [O.sub.6][(OH).sub.6]([Ag.sub.x][Pb.sub.y])[Cl.sub.x+2y], x + y [is less than or equal to] 2, Z = 1, was solved and refined using data collected at the Advanced Photon Source-GSE-CARS facility, using a 2 x 2 x 40 [[micro]m.sub.3] single crystal. The structure is trigonal, space group P[bar]31m, a = 10.145(1), c = 4.9925(9) [Angstrom], V = 445.0(1) [[Angstrom].sup.3], and was refined to R = 5.1 for 395 unique observed reflections. [Te.sup.6+][O.sub.6] octahedra and Jahn-Teller distorted [Cu.sup.2+][O.sub.4][(OH).sub.2] octahedra share edges to form layers parallel to (001), and Zn[O.sub.2][(OH).sub.2] tetrahedra share vertices to form six-member rings parallel to (001). Layers of octahedra and tetrahedra alternate along c, and form a new framework structure by vertex sharing. Channels through the framework parallel to c are occupied by Ag, Pb, and Cl ions. Electron microprobe analysis revealed Ag and Cl overlooked in the original microchemical analysis. Up to one-third of the Ag was substituted by Pb, and a Pb-rich analog may exist.