The crystal structure of atacamite and the crystal chemistry of cupric compounds

Abstract

The co-ordinates assigned in an earlier study of the crystal structure of atacamite, Cu2Cl(OH)3 or CuCl2.3Cu(OH)2, have been revised. Each Cu atom is shown to have four nearest OH neighbours (mean Cu—OH distance 2.01 A.), and in addition two more neighbours completing distorted octahedral co-ordination groups. For one-half of the Cu atoms these are one OH (at 2.36 A.) and one Cl (at 2.75 A.), and for the remainder, two Cl (at 2.76 A.). A comparison is made of the structures of CuCl2, Cu2Br(OH)3 and Cu2Cl(OH)3.