Structural units of cuprates in natural Cu-oxysalts.

The structure of copper oxysalt minerals is analyzed on the basis of the classification scheme developed earlier for synthetic cuprates. The copper-oxygen compounds were considered as the salts of hypothetical copper acids with characteristic Cu-containing structural units of various dimensions formed by a polymerization of the CuO squares. The results of magnetic susceptibility measurements performed recently were analyzed from the viewpoint of the developed extended structural classification scheme. The dimerization of magnetic moments was considered as a property of cuprates which was strongly dependent on the type of Cu-containing structural unit. A further extension of the structural classification scheme for cuprates is also discussed.