Abstract
Mineragraphic and X-ray studies of battery reactive manganese oxide ores from the Philipsburg District indicate that the manganese oxide minerals, in order of decreasing abundance, are cryptomelane, Nsuta MnO 2 pyrolusite, todorokite, chalcophanite, manganite, hydrohetaerolite, birnessite and coronadite. Impurities include quartz, muscovite, montmorillonite-illite, goethite and calcite.The oxide ores are secondary in origin and have formed by replacement of rhodochrosite, replacement of earlier secondary oxides, cavity filling, and residual accumulation. Cryptomelane, Nsuta MnO 2 , todorokite, pyrolusite and manganite are found in ores formed by cavity filling and replacement. Chalcophanite and birnessite are restricted to ores formed by cavity filling.There is no fixed paragenetic sequence of oxides. In general, early formed oxides include manganite, Nsuta MnO 2 , cryptomelane, and pyrolusite. Oxides intermediate in age include cryptomelane and todorokite. Chalcophanite, birnessite and some pyrolusite, cryptomelane, and manganite are late relative to other oxides.Mineralogic differences in the oxide ores can be related to their modes of formation and to factors that determine the extent of oxidation. These factors include the local lithology of the host rock, depth, subsurface solution passageways, the water table, and local differences in the composition of ground water.
