Abstract:
Characteristics of vernadite in manganese ores from Gangpur Group of rocks, Goriajhor Formation, Sundargarh district, Orissa, have been described. This terrestrial vernadite is distinguished from delta-MnO2 in marine manganese nodules by its well ordered crystallinity and thinner fibrils of submicron size. It appears to be chemically homogenous with the proposed formula: (Ba, K, Fe) MnO2.nH(2)O. This vernadite probably originated through solution, precipitation and redeposition under supergene conditions and later transformed into cryptomelane or romanechite.