Mineralogická charakteristika polymetalického rudního výskytu Dobrá Voda u Telče (moldanubikum, Česká republika)

Results of new electron-microprobe and sulfur isotope studies of a small vein-type Pb-Zn(-Ag) ore occurrence at Dobrá Voda near Telč are presented in this paper. The ore veins are situated at the contact of granites of the Central Moldanubian Pluton and migmatitized paragneisses of the Monotonous Group. The gangue is dominated by quartz containing small amounts of illite-muscovite, a mineral from the kaolinite group, and Fe-rich chlorite. The prevailing sulfide minerals are galena (with low contents of Ag and Sb) and sphalerite (with 0.123 - 0.175 apfu Fe, 0.004 - 0.006 apfu Cd, and 0.001 - 0.002 apfu Mn). Less frequent are pyrite and arsenopyrite, rare are microscopic grains of chalcopyrite, monoclinic pyrrhotite, kenoargentotetrahedrite-(Fe), pyrargyrite, and canfieldite. Native silver reported in literature was not confirmed. Supergene minerals are represented by acanthite, anglesite, mimetite, galena II, malachite, and smithsonite. The δ34S values of sphalerite and galena range between 2.7 and 5.4 ‰ CDT for most samples. Based on various compositional and isotope thermometers we presuppose that the main part of the studied hydrothermal mineralization originated at rather high temperatures (›ca. 300 °C). The mineral assemblage, chemical composition of minerals, and formation conditions of ore mineralization from Dobrá Voda correspond to the Freiberg-type base-metal mineralization (k-pol), widespread in the area of the Českomoravská vrchovina Mts.