Hoppanová E., Ferenc Š, Mikuš T., Dolníček Z., Kopáčik R., Vlasáč J. & Šimonová V., 2024: Hydrothermal quartz-baryte veins containing Pb-Cu-Sb-(Bi) mineralization at Brusno-Brzáčka occurrence (Veporic Unit, Central Slovakia) and their supergene alteration. Acta Geologica Slovaca, 16, 1, 1–17.

Hydrothermal quartz-baryte veins containing Pb-Cu-Sb-(Bi) mineralization at Brusno-Brzáčka occurrence (Veporic Unit, Central Slovakia) and their supergene alteration

Eva Hoppanová¹, Štefan Ferenc¹, Tomáš Mikuš², Zdeněk Dolníček³, Richard Kopáčik¹, Jozef Vlasáč² & Viera Šimonová¹

¹Department of Geography and Geology, Faculty of Natural Science, Matej Bel University, Tajovského 40, 974 01 Banská Bystrica, Slovakia; ehoppanova@umb.sk
²Earth Science Institute of the Slovak Academy of Sciences, Ďumbierska 1, 974 11 Banská Bystrica, Slovakia
³Department of Mineralogy and Petrology, National Museum,Cirkusová 1740, 193 00 Praha 9-Horní Počernice, Czech Republic

Abstract

The Brusno-Brzáčka occurrence (N 48.7698772°; E 19.4128150°) is located near the Brusno village (Slovenské Rudohorie Mts. Veporic Unit). Historically, the mineralization was explored by small-scale mining works located at the contact between the siliciclastic rocks of the Upper Permian and the Lower Triassic age. Paleo-Alpine metamorphic-hydrothermal mineralization is represented by quartz, baryte, or quartz-baryte veins, containing weak ore mineralization. Its succession is as follows: coarse-grained quartz I, pyrite (mineralization period I); baryte (II); tetrahedrite-(Zn), chalcopyrite (III); galena (IV) and quartz II (V). Supergene alteration produced initially covellite and spionkopite in the cementation zone. The oldest minerals in the oxidation zone are goethite, pyromorphite and mimetite. They were succeeded by the crystallization of Ba-rich anglesite, which partly overlaps in time with the precipitation of slightly younger anglesite. The formation of baryte partly overlaps with the deposition of anglesite, but in most cases, it is clearly younger. Bismutite is the youngest supergene mineral. A solid solution of anglesite–baryte with a Ba content from 0.29 apfu up to 0.51 apfu (i.e., Ba-rich anglesite) was identified at the studied site. This mineral phase covers the field of immiscibility of the natural solid solution PbSO₄ – BaSO₄, but the Ba/Pb ratio practically does not enter the baryte field (Pb-rich baryte).

Key words: sulphide mineralization, quartz-baryte vein, supergene alteration, baryte-anglesite solid solution, Veporic Unit, Slovenské Rudohorie Mts., Western Carpathians

Manuscript received: 2023-12-05

Revised version accepted: 2023-02-23