Eisen-TitanlagerstÌtten bei Raudsand, Westnorwegen.

Abstract

A number of magnetite-ilmenite deposits near Raudsand in western Norway are described. The orebodies lie in lenses and plates of amphibolite. These amphibolites are conformable within the surrounding late precambrian or eocambrian gneisses. The ore appears as lenses and plates with a marked banding which strongly reminds one of sedimentary layering. The ore is to be found in the marginal parts of the amphibolites, especially in wedges entering the surrounding gneisses. The ore bodies are folded during the caledonian orogeny together with the other rocks. The fold axis is roughly parallel to the Molde-Tingvoll syncline which is the main structural element in the region. The Rødsand mine is producing 430 000 t crude ore per year from four different amphibolite lenses. The ore minerals are magnetite, ilmenite and little pyrite, pyrrhotite and chalcopyrite. The magnetite is very pure. The ilmenite contains 17,7% hematite, mostly as very fine inclusions. None of the other deposits near Raudsand are productive. The TiO2:Fe relation is very similar for all these ores, but very different from those of other deposits in western Norway. The mineralogical-petrographical picture is due to metamorphism and the author believes that the macroscopic features can give the best information on the genesis of the ore.