Mineralogy of epithermal Au mineralization in the eastern part of the mine Rozalia (Hodrusa-Hamre)

The central zone of the large Miocene Stiavnica stratovolcano in the Western Carpathians hosts epithermal Au mineralization, located at deep levels of the historic Rozalia base-metal mine at Banska Hodrusa. The mineralization occurs as sub-horizontal veins at the base of the pre-caldera andesite. The veins are dismembered by quartz-diorite porphyry sills and displaced by younger, steeply dipping Rozalia base-metal vein structures, which are related to resurgent horst uplift in the caldera center. The Au mineralization formed during three stages. The second stage of mineralization produced the principal gold ore within the deposit. Quartz is the main gangue vein filling mineral accompanied by variable amounts of Ca-Mn-Fe-Mg carbonates (calcite, rhodochrosite, dolomite, ankerite and siderite) and silcicates - rhodonite, chlorite, K-feldspar and illite. Sphalerite and galena are the main ore-bearing minerals accompanied by chalcopyrite, gold, pyrite and telluride minerals (hessite, petzite). Gold occurs as micro- to macroscopic gold flakes or disseminated grains in quartz, rhodonite, carbonates or in association with major sulphides and tellurides. Gold shows a strong affinity to galena. Typical textures of vein filling minerals include hydrothermal breccia (cockade) and banded type. (authors)