Chemical composition of the internal layers of manganese deposits from the South Pacific Ocean

The chemical composition of layered deposit inside zones has been determined for ferromanganese nodules and crusts retrieved in the South Pacific Ocean during various R/V Eltanin cruises. Samples were prepared from the nodules and crusts by peeling or scraping successive layers and measuring the resultant decrease in thickness with calipers. The samples were then ground to a fine powder and split into two aliquots, one for U and Th isotopic analysis, the other for elemental analysis. Mercury was determined by flameless atomic absorption spectrophotometry. The remaining elements were determined by standard atomic absorption spectrophotometry. The errors for all elemental determinations are estimated to be 10% or better.