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  • Author: Martin Chovan x
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Mineralogy and Geochemistry of the Nižná Boca Sb-Au Hydrothermal Ore Deposit (Western Carpathians, Slovakia)

Samples from hydrothermal Sb-Au mineralization in the area SE of Nižná Boca village in the N&iAzke Tatry Mountains were investigated using a variety of geochemical and mineralogical methods. Ore minerals typically occur in N-S striking quartz-carbonate veins hosted by an I-type biotite granodiorite to tonalite of Variscan Age (the Ďumbier Type). Paragenetic associations in the deposit are comparable to other mineralizations of the same type in the Ďumbierske Nízke Tatry Mountains. A quartz-arsenopyrite, pyrite stage of mineralization is the oldest with a calculated temperature of formation of about 445°C. It is followed by a quartz-carbonate-stibnite, zinkenite stage and, in turn, a quartz-carbonate-sphalerite-galena, boulangerite-gold stage. The gold typically contains between 9-18 wt.% Ag regardless of mineral association. No evidence for further generations of gold was found although it is possible that some gold was remobilized from the structure of the auriferous arsenopyrite. The Au and Ag content of the bulk ore ranges from 0.53 g.t-1 to 20.2 g.t-1 and from 0.9 g.t-1 to 31.2 g.t-1, respectively. A tetrahedrite-chalcopyrite stage is followed by a barite-hematite stage - the youngest assemblage in the deposit. Fluid inclusions from the first mineralization stage are usually less than 3 μm in size and contain less than 3.6 wt.% CO2; salinity, density and homogenization temperature range from 2.7-16.3 wt.% NaCl(eq), 0.85-1.03 and 128-280°C, respectively.

A Note on the Chemical Composition of Nuffieldite Solid-Solution From Sulphide Mineralizations in the Western Carpathians, Slovakia

The chemistry of the rare sulphosalt nuffieldite from three localities in Slovakia is examined. Nuffieldite is a part of a complex association of Bi sulphosalts accompanying tetrahedrite mineralization in some sulphide deposits in the Western Carpathians. Cu + Pb = (Bi, Sb) + vac. substitution in nuffieldite and the general formula Cu1+xPb2Bi2(PbxSbyBi1-x-y)S7 where 0 < x < 0.34; and 0.32 < y < 0.45 are confirmed. Decreasing Sb content with increasing copper content indicates a predominant substitution of Bi by Sb in nuffieldite.

Elemental and mineral inventory of tailing impoundments near Pezinok, Slovakia and possible courses of action for their remediation

An effective remediation strategy for a polluted site should take the absolute amount of the pollutant(s) into account. Here, we present an elemental budget for As, Sb and Fe in two tailing impoundments of the former Sb-Au deposit near Pezinok, Slovakia. The two impoundments contain 5,740×103 kg As, 6,360×103 kg Sb and 50,105×103 kg Fe. An estimated total Au content in the impoundments is 132 kg. The most abundant minerals in the tailings are quartz, illite, and chlorite. The content of carbonates in the tailings is 3.5-10.5 wt% calcite equivalent and we estimate that the carbonates are sufficiently abundant to buffer the pH at circumneutral values, up to the point when all pyrite decomposes. The possible courses of action are i) do nothing, ii) build an active barrier to capture the released As and Sb, iii) isolate the impoundments from rain and ground water and iv) use the impoundments as a source of Sb and redeposit the waste in a safer form. The simplest approach is to do nothing, which seems to be the most likely course of events, given the current economic, political and societal state of the Slovak Republic. Although this action costs nothing in the short term, it may cause significant damage to the environment, especially to the alluvial sediments and associated water resources in the long term.