The paper gives systematized and generalized information on manganese formations from the northern and southern summits of Belyaevsky Seamount in the Sea of Japan. This information shows that low-temperature hydrothermal fast-growing crusts are spread on the seamount widely. The crusts have bedded structure. Their textures are collomorphic and fibrous. The main ore minerals are birnessite and todorokite while the accessory minerals include vernadite, manganite, and pyrolusite. There are samples where ore minerals form veinlets in basalts and cement aggregates of clay minerals like smectite-hydromica. Silica minerals and barite crystallized at final mineralization stages. Micro-sized mineral phases of Cu, Zn, Sn, Ni, W, Cr, Ag, Ce, La, and Nd containing in the crusts and classifying by chemical composition as native, sulfide, sulfate, oxide, and intermetallic are obviously superimposed and meet high- and medium-temperature conditions of mineral formation. Crusts’ bulk chemical composition demonstrates abundances of Mn, Ba, Sr, and Li, as well as depletion of Fe, Al, Ti, and many trace elements. Positive Ce anomalies are likely to record the layers formed in the crusts due to the hydrogenic substance supply with hydrothermal ore formation processes being under attenuation.