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Paleozoic Iron Ore Occurrences in the Medvednica Mountain, Croatia

Magnetite-hematite ore occurrences are situated on the south-western slopes of the Medvednica Mt. (Fig. 1). They occur in the Paleozoic greenschists along the contact or very close with the Paleozoic sedimentary complex. Ore zone is 6 km long and strikes from Pustodol-Adolfovac to the Tisova Peć. First 1.5 km (Adolfovac-Blznec Potok) contains the majority of 20 ore outcrops. Ore zone consists of discontinous decameters long and 2 to 3.5 m thick bedded lenses, poorly mineralized (20-35 % Fe). The ore bearing zone is characterized by muscovite-chloritoid schists, quartz-stilpnomelane-magnetite schists, quartz-stilpnomelane-chlorite-magnetite schists and iron-ore bearing schists. First detailed geologisal, geophysical and mining investigations took place between 1954 and 1956, but with negative results. Ore minerals are concentrated in certain thin beds (1-2 mm). The strongly mineralized thin beds are significantly fewer than the weakly mineralized bed and bands alternate at very short intervals. Locally we may observe that one or more thin rich beds are followed by a thicker series of weakly mineralized beds that are sometimes almost sterile.

Iron deposits; SEDEX-type; Paleozoic; Medvednica Mt.; Croatia

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