Chemical composition of manganese nodules from the Tasman Sea

During a short geological cruise in May 1979 by HMAS Kimbla, two manganese nodules were recovered from the deep sea about 250 nautical miles southeast of Sydney. They were laying on a greenish gray calcareous mud. The manganese nodules are subspherical with a rather irregular and rough surface, and are about 10 em in diameter. They consist of numerous concentric shells, many less than 0.1 mm thick, of brown and black metal oxides, and pale yellowish clay, in roughly equal proportions. The metal contents of the nodules (dried at 105°C) were determined at the Australia Bureau of Mineral Resources, Geology and Geophysics (BMR) using the atomic absorption method for Mn, Ni, Cu and Co, and a volumetric method for Fe.