Major elements in manganese and iron oxides precipitated from seawater

Abstract

manganese and iron oxides precipitated from aerated well-seawater at aquaria in Japan were analyzed for their mineralogy and alkaline earth and alkali metal contents. Todorokite-rich manganese oxides were enriched in Na and Ca and depleted in K and Mg relative to birnessite-rich manganese oxides. The concentrations of alkaline earths and alkali metals in the iron oxide were lower than in the manganese oxides; this is especially true of the alkali metals. On the basis of these results, mineralogical control on the major element composition and the charge-balancing cations of marine ferromanganese oxide deposits are discussed.