QUETZALCOATLITE: A NEW OCTAHEDRAL-TETRAHEDRAL STRUCTURE FROM A 2 X 2 X 40 μM3 CRYSTAL AT THE ADVANCED PHOTON SOURCE-GSE-CARS FACILITY

Abstract

The structure of quetzalcoatlite, Zn6Cu3(TeO3)2O6(OH)6(AgxPby)Clx+2y, x + y ≤ 2, Z = 1, was solved and refined using data collected at the Advanced Photon Source-GSE-CARS facility, using a 2 × 2 ×40 μm3 single crystal. The structure is trigonal, space group P3̅1m, a = 10.145(1), c = 4.9925(9) Å, V = 445.0(1) Å3, and was refined to R = 5.1 for 395 unique observed reflections. Te6+O6 octahedra and Jahn-Teller distorted Cu2+O4(OH)2 octahedra share edges to form layers parallel to (001), and ZnO2(OH)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.