Manganese: past, present, future and applied geology

摘要

Three types of manganese deposits have produced the great bulk of the high-quality manganese ore used in industry. These are: manganese carbonate deposits in 'Early' Precambrian volcanic terranes (greenstone belts) in Brazil, Guyana, Burkina Faso, Ghana and Zaire; manganiferous silicate/carbonate beds in certain distinct banded iron formations in Brazil and South Africa; and manganese-rich beds deposited at the margins of epicontinental basins in Australia, Brazil, Gabon, Georgia and Ukraine. Most of these deposits have been altered and enriched by supergene processes, leading to the formation of prominent, easily discovered outcrops. Declining intensity of manganese use in the steel industry has been offset by rising global steel production, and annual manganese ore demand through 2020 is expected to stabilize in the range 20-22 million tonnes. Changing circumstances and declining ore price have discouraged exploration for new deposits. Known higher quality resources are being depleted, and, in the absence of new discovery and development, a significant supply shortfall is probable by the year 2020. Upward pressure on ore price may lead to renewed search for new deposits. Certain banded iron formations are the most favourable targets for the discovery of concealed manganese deposits.