Sedimento-metamorphic manganese deposits within Tiantaishan Forma-tion of Lower Proterozoic Hongan Group in northeastern Hubei are of theoldest manganese deposits in China. Primary ores, consisting of rhodochrosite,kutnohorite, spessartine, jakobsite and bixbyite, were formed by si, Al-bear-ing manganese carbonate sediments through regional high-pressure dynamic metamorphism in Jinning Period. During the supergene process, primary oreswere converted into oxidized ores comprising todorokite, hollandite, rancieite and pyrolusite which make up a manganese stain type mineral association. The formation of the manganese deposits has experienced sedimentary,metamorphic and supergene stages. The sedimentary stage laid. the material foundation of these deposits; metamorphism changed the modes of occurrence of major elements and, in particular, coarsened the grain size of manga-nese and phosphorous minerals, which benefits the separation of P from Mn in the process of ore dressing: In the supergene process, Mn was further enriched, thus raising the grade of manganese ores.