抄録
The occurrence of nsutite and manganoan nsutite is reported for the first time from Goriajhar manganese deposit in Gangpur group of rocks, India. Detailed mineralogic and geochemical characteristics of these phases are described. Mn3+ rather than Mn2+ is found to coexist with Mn4+ ion, the general formula being (Mn3+, Mn4+) (O, OH)2. These are formed from the host gonditic rocks through oxidation and precipitation processes under supergene enrichment condition.
