Original paper

Crystal structure of mahnertite

Pushcharovsky, Dmitry . Y.u.; Zubkova, Natalia V.; Teat, Simon J.; Maclean, Elizabeth; Sarp, Halil

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European Journal of Mineralogy Volume 16 Number 4 (2004), p. 687 - 692

published: Jul 15, 2004

DOI: 10.1127/0935-1221/2004/0016-0687

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Abstract

Mahnertite, (Na0.88 Ca0.12)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) Å 3 ,Z = 8, ρ o = 3.32, ρ c = 3.14 g/cm3, μ = 9.78 mm-1. The crystal structure of mahnertite was solved and refined against data collected at the Daresbury S ynchrotron Radiation Source, using a 20 × 20 × 2 μ m3 single crystal, λ = 0.6898 Å, F (000) = 2150, R = 0.049 for 639 reflections with I > 2 σ (I). The structure consists of sheets parallel to (001), which comprise two symmetrically independent distorted Cu 5-vertex square pyramids Cu ϕ 5 (ϕ = O, Cl or H2 O) as well as AsO4 tetrahedra. Four Cu ϕ 5 pyramids located around the 4-fold axis share e dges to form clusters linked by AsO4 tetrahedra. The sheets are linked by the common apical vertex of the Cu(2) ϕ< 5 polyhedra. as a result, a heterogeneous framework is formed. (na, ca) atoms, additional cu(3) cations and h2 O molecules are located in the interlayers. The mineral is structurally related to zdenekite, NaPbCu<5 (AsO4)4 Cl ⋅ 5H2 O.

Keywords

mahnertite • crystal structure • arsenate