Bulk chemical analysis of selected manganese nodules retrieved during VA13/2 cruise in the Equatorial North Pacific

Manganese nodules from VA13/2 cruise (R/V Valdivia) were selected for a variety of morphologies and size. They were regrouped by size class and chemically analyzed in bulk. Mn, Fe, Ni, and Cu concentrations were determined by X-ray fluorescence spectroscopy following grinding and drying of the samples at 1l0°C for 24 hr. The elements Co, Zn, Al, Si, and Ba were analyzed in selected samples by atomic absorption spectrophotometry in Aachen. In addition, the percent lithogenous fraction of selected samples was determined following treatment of the sample by 25 percent HCl. Element composition in these nodules was then computed on a lithogenous-free basis to make allowance for the effects of variation in the silicate contents of the nodules.