Selenium-Rich Ag–Au Mineralization at the Kremnica Au–Ag Epithermal Deposit, Slovak Republic

Abstract

Selenium-rich Au–Ag mineralization has been discovered in the Kremnica ore district, central Slovakia. The mineralization is hosted by a single quartz–dolomite vein hosted by Neogene propyllitized andesites of the Kremnica stratovolcano. Ore mineralogy and crystal chemistry of individual ore minerals have been studied here. The early base-metal ore mineralization composed of pyrite, sphalerite, and chalcopyrite lacks selenium, whereas the superimposed Au–Ag paragenesis is Se-enriched. The Au–Ag alloys, uytenbogaardtite, minerals of the galena–clausthalite series, acanthite–naumannite series, diaphorite, miargyrite, pyrargyrite–proustite, polybasite group, minerals of the tetrahedrite group and andorite branch (andorite IV, andorite VI, Ag-excess fizélyite), freieslebenite, and rare Pb–Sb sulphosalts (scaiinite, robinsonite, plagionite) have been identified here. Besides selenides, the most Se-enriched phases are miargyrite, proustite–pyrargyrite, and polybasite–pearceite, whose Se contents are among the highest reported worldwide. In addition, one new phase has been found, corresponding to a Se-analogue of pearceite containing 2.08–3.54 apfu Se. The style of mineralization, paragenetic situation, and chemical trends observed in individual minerals are comparable to those of Au–Ag low-sulphidation epithermal Au–Ag mineralizations of the Kremnica and neighboring Štiavnica and Hodruša-Hámre ore districts. However, the pronounced enrichment in selenium is a specific feature of the studied vein only.

Ag-Pb-Sb Sulfosalts and Se-rich Mineralization of Anthony of Padua Mine near Poličany—Model Example of the Mineralization of Silver Lodes in the Historic Kutná Hora Ag-Pb Ore District, Czech Republic

“…This is the first occurrence of uytenbogaardtite in the Czech Republic. Recently, uytenbogaardite was described from the selenium-rich Au-Ag mineralization of the Kremnica Sb-Au-Ag epithermal deposit, Slovakia [72]. The chemistry of uytenbogaardtite from Kutná Hora (Table 26) shows a surplus of silver (3.16-3.33 apfu) and a deficit of sulphur (1.66-1.87 apfu) at all four analysed points.…”

Argentotetrahedrite-(Zn), Ag6(Cu4Zn2)Sb4S13, a new member of the tetrahedrite group

“…Macroscopic aggregates of older common sulfides (sphalerite, pyrite and minor chalcopyrite) up to 5 mm as well as late-stage Ag-sulfosalts (mainly miargyrite, pyrargyrite and proustite) up to 2 mm are scattered locally in both quartz and dolomite. A Se-enriched association of ore minerals from this vein was studied in detail by Števko et al (2018) with Au–Ag alloys, uytenbogaardtite, minerals of the galena–clausthalite and of the acanthite–naumannite series, diaphorite, miargyrite, pyrargyrite–proustite, members of the polybasite group, various minerals of the tetrahedrite group and andorite branch (quatrandorite, senandorite, Ag-excess fizélyite), freieslebenite as well as Pb–Sb sulfosalts (scainiite, robinsonite and plagionite) being identified.…”

Unique Association of Sulphosalts from the Kľačianka Occurrence, Nízke Tatry Mts., Slovak Republic

“…Minerals 2021, 11, x FOR PEER REVIEW 3 of 24 38]. The crystalline basement is overlain by autochtonous to para-autochtonous Mesozoic sedimentary cover rocks (the Tatric Envelope Unit).…”

“…The ideal formula of scainiite contains five oxygen atoms, but this low O content (0.96 wt.% according to the crystallographic study of Moëlo et al [58]) cannot be measured precisely with an EPM [57] due to presence of an oxidation film on the surface of the samples [14,57,59]. Unlike samples from the type locality, scainiite from Kl'ačianka contains minor contents of Cl up to 0.14 apfu; similar contents were also detected in samples from Dúbrava (0.17-0.33 apfu; Sejkora, unpublished data) or Kremnica deposit (up to 0.19 apfu [24]). The chemical analyses of scainiite and corresponding empirical formulae are given in Table S3.…”

“…This research is based not only on routine electron microprobe data, but also on the study of minor elements (as Hg, Cu, Cl etc.) in the chemical composition of sulphosalts [23][24][25], single-crystal X-ray diffraction [16], powder X-ray diffraction [26,27], or Raman spectroscopy [27,28].…”