Size, surface texture, chemical composition and mineralogy interrelations in ferromanganese nodules of central Indian Ocean

Abstract

Fiftyseven ferromanganese nodules, classified into 3 size class ( < 4,4-6 and 6-8 cm diam.), from the siliceous sediments of central Indian Ocean were analysed for transition metals and representative sample from each size class for mineralogy. Smaller (< 4 cm diam.) nodules are invariably rough and very rough and spherical; they have higher concentration of Mn, Ni and Cu. The intensity of todorokite reflection decreases in higher size ( > 4 cm diam.) class. These observations suggest that the smaller nodules appear to have been influenced more by diagenetic processes that the larger nodules.