Genesis and paragenesis of the tetravalent manganese oxides of the Australian continent

The tetravalent manganese oxide minerals of the weathering crust of the Australian continent are grouped into lateritic association, ultramafic association, carbonate association, shale association, lacustrine association, ancient marine crust association, and desert varnish association on the basis of field observations of mineral occurrences. Although the formation of manganese oxides is controlled by the well-known Eh-pH relationship, the specific manganese mineralogy is hypothesized to be influenced by the presence of accessory ions or structural templates characteristic of specific geologic environments.