Quetzalcoatlite: A new octahedral-tetrahedral structure from a 2 × 2 × 40 μm3 crystal at the Advanced Photon Source-GSE-CARS Facility

The structure of quetzalcoatlite, Zn₆Cu₃(TeO₃)₂O₆(OH)₆(Ag_xPb_y)Cl_x+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) ų, 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.