Den manganholdige siderittmalm i Rubben, Troms. Undersøkelser sommeren 1959.
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An occurence of mangan-bearing siderite ore i Rubben, Troms, Northern Norway. An occurence of manganese-bearing siderite ore i Rubben, Torms, Northern Norway, was investigated during some days in the summer of 1959, and is here briefly described. The country rocks are mica schists, amphibolites and limestones. The thin amphibolitic beds are supposed to be basic tuffs or tuffites: they consist mainly of a light green hornblende and oligoclase. The mica schists are muscovite-biotite schists of a type very common in the Caledonien mountain chain in Norway. A thin bed of limestone is often found at the base of the siderite ore. The ore is exposed at various places, the extension of the ore-bearing area being about 2,5 kilometers. The chief mineral in the ore is a manganiferous siderite. Lesser amounts of magnite (5-8%) quartz and garnet commonly occur. The ore is finegrained with a gray colour and at the surface it is altered to oxydic minerals with brown, black or blue colour. The iron content of the ore varies between 31 and 48% Fe, the manganese content is 5-8%. An analysis of the pure carbonate is shown in Table 1. The ore is supposed to be metamorphosed sedimentary beds.