Occurrence of manganese carbonates ores on strata-bound Horní Benešov deposite (Silesia, Czech Republic)


Authors: Reif J

Published in: Bulletin of Geosciences, volume 75, issue 4; pages: 449 - 454;

Keywords: Šternberk-H. Benešov Belt, strata-bound deposite, Devonian, manganese carbonate and iron oxide ores, mineralogy,

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Occurrence of manganese carbonates ores represented by rodochrosite and Fe-rodochrosite with inferior amount of siderite, ferrostilpnomelane, chlorite, limonite, hematite and magnetite was discovered on Horní Benešov sulphides deposit. Lattice parametres of rodochrosite are a = 0.4765(2) nm, c = 1.5674(2) nm and for siderite a = 0.4693(1) nm, c = 1.5462(3) nm. Chemical composition of rodochrosite was as follows: 79.5 % MnCO3, 17,5 % FeCO3, 2.6 % CaCO3, 0.3 % MgCO3. Rodochrosite was observed as relatively small grained or concentric radial agregate. Agregates of rodochrosite represented originally very small grade metamorphosed relicts of volcano-sedimentary ore accumulation. Mn-carbonates ores were probably a primary source of secondary wad and psilomelane accumulations in the supergene zone of Horní Benešov sulphide deposit. The isotopic compositions of C and O of siderite were - 26.6 ‰ delta;13C and 22.9 ‰ delta;18O (average of 2 measurement) and for rodochrosite - 14 ‰ delta;13C and 22.8 ‰ delta;18O.