The crystal structure of christelite Zn3Cu2(SO4)2(OH)6 · 4 H2O

Abstract

Abstract The crystal structure of christelite Zn3Cu2 · (SO4)2(OH)6 · 4 H2O (space group P[unk]; lattice parameters a = 5.4143(8) Å, b = 6.336(1) Å, c = 10.470(3) Å, α = 94.32(3)°, β = 90.06(2)°, γ = 90.27(2)°) was solved using direct methods and difference Fourier-syntheses. The structure was refined to a final R(F)-value of 0.033. The structure contains distorted [(Zn, Cu)O6] octahedra which are connected as to form sheets of composition ∞ 2[(Cu,Zn)2(OH)3O]−. These sheets are similar to those observed in the mineral ktenasite. In both structures sulphate groups are attached to the sheets of octahedra through common vertices. In christelite the tetrahedral [SO4] groups are linked to isolated [Zn(H2O)4O2] octahedra thus forming a three-dimensional structure, whereas in the structure of ktenasite the [SO4] tetrahedra are bonded to isolated [Zn(H2O)6] by a system of hydrogen bonds. The relationship of christelite with other minerals is pointed out and discussed.