Mahnertite, (Na0.88Ca0.12)Cu2.75[AsO4]2Cl0.62·3.63 H2O, M = 565.17, is tetragonal, with space group I4/mmm, a = 10.037(1), c = 23.739(1) Å, V = 2391.5(4) Å3, Z = 8, ρo = 3.32, ρc = 3.14 g/cm3, μ = 9.78 mm-1. The crystal structure of mahnertite was solved and refined against data collected at the Daresbury Synchrotron Radiation Source, using a 20 × 20 × 2 μm3 single crystal, Λ = 0.6898 Å, F(000) = 2150, R = 0.049 for 639 reflections with I > 2σ(I). The structure consists of sheets parallel to (001), which comprise two symmetrically independent distorted Cu 5-vertex square pyramids Cuϕ5 (ϕ =O, Cl or H2O) as well as AsO4 tetrahedra. Four Cuϕ5 pyramids located around the 4-fold axis share edges to form clusters linked by AsO4 tetrahedra. The sheets are linked by the common apical vertex of the Cu(2)ϕ5 polyhedra. As a result, a heterogeneous framework is formed. (Na,Ca) atoms, additional Cu(3) cations and H2O molecules are located in the interlayers. The mineral is structurally related to zdenekite, NaPbCu5(AsO4)4Cl·5H2O.

You do not currently have access to this article.