Uranium and Thorium in Deep-Sea Manganese Nodules from the Central Pacific

When the analytical results of 119 ferromanganese samples were considered on a more regional basis, the authors found that U enrichment generally occurred in samples with relatively high Fe contents. For all areas together, the correlation between Fe and Th was a factor less than the correlation between Fe and U (0. 454 and 0. 848, respectively). As the deposits of the investigated areas have high Ni and Cu contents when there is low U, it is suggested that U concentrations of 4-5 ppm, measured by a deep-sea scintillation counter unit similar to that already applied by Miller and Symons in the shelf area, may indicate useful manganese nodules deposits in this area.