(Table 1, page 400) Metal content of different manganese nodules from cruise VA-04 (R/V Valdivia) in the Pacific Ocean

Deep sea manganese nodules are considered as important natural resources for the future because of their Ni, Cu and Co contents. Their different shapes cannot be correlated clearly with their chemical composition. Surface constitution, however, can be associated with the metal contents. A classification of the nodules is suggested on the basis of these results. The iron content of the nodules strikingly shows relations to the physical properties (e.g. density and porosity). The method of density-measurement is the reason for this covariance. The investigation of freeze-dried nodular substance does not give this result. The Fe-rich nodules lose more hydration water than the Fe-poor ones during heat drying. The reason for this effect is the different crystallinity, respectively the particle size. The mean particle size is calculated on the basis of geometrical models. The X-ray-diffraction analysis proves the variation of crystallinity in connection with the Fe-content, too. The internal nodular textures also show characteristic distinctions.