Structural relations in copper oxysalt minerals. I. Structural hierarchy

Abstract

A hierarchical structural classification is developed for the copper oxysalt minerals, based on the polymerization of coordination polyhedra of higher bond valences, and focusing specifically on [3]-, [4]-, [5]- and [6]-coordinate polyhedra. The nature of copper oxysalt structures is complicated by the extremely distorted coordinations often occurring around the Cu 2+ cation, a result of the well-known Jahn-Teller effect. Although this is widely recognized at the qualitative level, it has led to a very inconsistent assignment of coordination numbers to Cu 2+ in mineral