Abstract:  Deep sea manganese nodules are classi?ed into three genetic types: hydrogenetic, diagenetic and mixed, according to their major metal sources. Hydrogenetic manganese nodule, derived from precipitates from sea water column, is generally characterized of smooth surface, Mn/Fe ratio <2, higher concentration of Co and ∑REE, and slower growth rate. In contrast, diagenetic manganese nodule, from pore water in sea?oor sediemnts, is of rough surface, Mn/Fe ratio >2, higher concentration of Cu and Ni, and relative faster growth rate. Classi?cation and identi?cation of ferromanganese minerals of manganese nodules have been very dif?cult and confused as most of or nearly all of them are amorphous and/or poor crystallized. Up to date, it is commonly accepted that major manganese minerals in hydrogenetic and diagenetic nodules are d-MnO2 and 10Å-manganates, respectively. Globally variation of nodule distribution, nodule types, nodule abundance, mineral and chemical composition in nodules is mainly controlled by primary production, carbonate compensate depth and oxygen minimum zone. Although progresses have been largely achieved for the genesis studies of manganese nodules in deep sea by numerous great efforts in last ~100 years, metallogenetic mysteries are still remain to be further explored.

Key words:  , ferromanganese nodule, genesis, mineral composition, controlling factor, mystery