Hodgesmithite, (Cu,Zn)₆Zn(SO₄)₂(OH)₁₀·3H₂O, a new copper zinc sulfate mineral with a unique, decorated, interrupted-sheet structure

Abstract

Hodgesmithite, ideally (Cu,Zn)6Zn(SO4)2(OH)10·3H2O, is a new copper zinc sulfate mineral from the Block 14 Opencut, Broken Hill, New South Wales, Australia. Electron microprobe analysis provided the empirical formula Cu4.84,Zn2.16,Cd0.04[(SO4)1.89,(SiO4)0.12]2.01(OH)9.82·3.15H2O based on 21 oxygen atoms per formula unit. Hodgesmithite is trigonal, space group P3, with a = 8.1905 (12), c = 7.0990 (14) Å, V = 412.43 (12) Å3 and Z = 1. The crystal structure of hodgesmithite, R1 = 0.0272 for 5145 reflections with Fo > 4σ(Fo) measured with synchrotron X‐ray radiation (λ = 0.71080 Å), contains interrupted sheets of edge‐sharing Cu(O,OH)6 octahedra in the (001) plane. Every seventh octahedral site is vacant and capped by a ZnO4 tetrahedron and an SO4 tetrahedron which are attached to the sheet above and below this position. The sheets are additionally decorated on one side by SO4 tetrahedra that share a vertex incident to three Cu—O(apical) bonds. Interstitial H2O groups lie between the sheets. ZnO4 tetrahedra share vertices with SO4 tetrahedra from the adjacent sheet to provide linkage between the sheets in the c direction.