Geochemical behavior of manganese in weathering environments and its significance in exploration

Under and climate conditions the chemical weathering of manganese ores is governed by the fugacities of O2, CO2 and S2 in the atmosphere and soils. Manganese minerals exhibit solid phase transformations without migration of Fe and Mn. Under tropical and subtropical humid climate conditions low-valent Mn is instable and apt to be oxidized into high valency state.High-valent Mn minerals are stable and easy to form secondary high-grade Mn ores.Secondary concentration is possible for Mn ores in carbonate formations, while those in clastic rocks tend to migrate and may be washed away.Such differences are the main obstacles in prospecting Mn ore deposits.