Chemical composition of selected manganese nodule and ferromanganese crust structure zones and morphology types (Expedition NZOI-Tangaroa_22 and MANGANESE 76, R/V Tangaroa)

If nodules were chemically homogeneous objects, their bulk compositions would paint a complete picture. But they are not, as can be assumed simply from visual recognition of their diverse structural elements. Successively finer sampling of individual nodules reveals an increasingly greater degree of inhomogeneity, the details of which are resolvable down to microprobe scale. For this study, the chemistry of the largest distinctly separable structural elements has been examined, in order to learn how much more information can be gained from such an approach than from whole-nodule analyses. Compositional data for selected nodule structure zones are presented in Appendix N. Concentrations were determined by atomic absorption spectrophotometry. The analysed part of the Mn nodule outer manganese rich rind or the outer part of the ferromanganese crust were dried at 110°C for about 48 hours, and ground to a fine powder.