Chemical and mineralogical investigations on deep sea manganese nodules from the Southern Ocean

Some observations on the chemical composition of todorokite

“…A line near 7A is often observed in todorokite specimens. The significance in this line is discussed by Ostwald (1984b). In relation to todorokite homogeneity, the association of a line at 7.1 7.2A with a line at 3.6A is suggestive of birnessite in the todorokite.…”

“…It would appear, however, that in regions where Ca is absent or in low concentration, Ba may take its place. In the Groote Eylandt manganese ore body, G quarry, the ore contains CaO 0.03~o, BaO 1.7~, K20 0.5 ~, and MgO 0.4 ~, and here a Ba-containing todorokite occurs (Ostwald, 1982a). In the Cretaceous-age sediments which enclose the stratiform manganese oxide deposit, disseminated carbonate ooliths occur in association with a Ca-containing todorokite (Ostwald, 1982b).…”

“…One difficulty with todorokite (and other manganese oxides) is that it commonly alters to a range of minerals including pyrolusite (Ostwald, 1982a), cryptomelane (Chukhrov et al, 1978), vernadite (Chukhrov et al, 1980), and possibly birnessite (Chukhrov et al, 1978), each mineral having its own suite of component elements. Thus both bulk analyses and electron probe microanalyses (EPMA) may be in error because of heterogeneity.…”

“…Locations are listed in Table I. The marine todorokites come from the Pacific Ocean (Ostwald, 1982b) and the SE Indian Ocean (Ostwald, 1984a).…”

Terrestrial ferro-manganese nodules formed in limestone areas of the Ryukyu islands II. Partitioning of major and minor chemical constituents determined by selective chemical leaching technique.

“…Strongly positive Fe-Co and Mn-Co correla tions are often observed in both oceanic and terrestrial ferro-manganese nodules (Sano and Matsubara, 1970;Ostwald and Frazer, 1973;Taira et al, 1981).…”