ASPECTS OF RHODIUM MARINE CHEMISTRY

Rhodium, one of the least abundant of the Pt-group elements in the ear th's crust, has the second highest concentration in seawater. This may be a consequence of strong complexing, perhaps kinetically restrained with time constants of the order of centuries to millenia. The elemen t shows a nutrient-like distribution in waters of the Pacific Ocean. P elagic and coastal sediments have Rh concentrations close to crustal v alues. There is a remarkable enrichment of Rh in ferromanganese minera ls that cannot be explained by oxidative capture. Unlike the other Pt- group elements, Rh is enriched in the high temperature hydrothermal su lfide deposits as well as phosphorites.