Manganese crusts and nodules in Jurassic limestones correspond to those formed on recent submarine pelagic or hemipelagic non-deposition surfaces and hardgrounds. The ore mineralization is represented by pyrolusite, romancchite, manganite, and iron hydroxides. The structure of the manganese minerals, Mn/Fe and Si/Al ratio and Co, Cu, Ni and REE distribution in the ores indicate hydrogenetic and diagenetic accumulation of manganese minerals. Later, Cretaceous supergene accumulation filled fissures and cavities in the limestones.