Martin Chovan

A mineralogical, geochemical, and microbiogical assessment of the antimony- and arsenic-rich neutral mine drainage tailings near Pezinok, Slovakia

Abstract The mineralogical composition of mining wastes deposited in voluminous tailing impoundments around the world is the key factor that controls retention and release of pollutants. Here we report a detailed mineralogical, geochemical, and microbiological investigation of two tailing impoundments near the town of Pezinok, Slovakia. The primary objective of this study was the mineralogy that formed in the impoundment after the deposition of the tailings (so-called tertiary minerals). Tertiary minerals include oxyhydroxides of Fe, Sb, As, Ca and are present as grains and as rims on primary ore minerals. X-ray microdiffraction data show that the iron oxyhydroxides with abundant As are X-ray amorphous. The limiting (lowest) Fe/As (wt/wt%) ratio in this material is 1.5; beyond this ratio, the hydrous ferric oxide does not retain arsenic. The grains with less As and little to moderate amounts of Sb are goethite; the grains where Sb dominates over Fe are poorly crystalline tripuhyite (FeSbO4). Even the most heavily contaminated samples (up to 29 wt% As2O5) are populated with diverse communities of microorganisms including typical arsenic-resistant heterotrophic species as well as iron reducers and sulfur oxidizers. Several recovered clones cluster within phylogenetic groups that are solely based on environmental sequences and do not contain a single cultivated species, thus calling for more work on such extreme environments.

Origin of the fluids associated with granodiorite-hosted, Sb-As-Au-W mineralisation at Dbrava (Nzke Tatry Mts, Western Carpathians)

Mineral parageneses of the polymetallic, Sbrich deposit at Dúbrava has been formed during five separated stages. A fluid inclusion study demonstrates that the earliest stages with scheelite, molybdenite and arsenopyrite have been associated with immiscible CO2 (± CH4)-rich, low-saline fluids at temperatures between 300 and 400 °C and pressures as much as 2 kbar. Deposition of the main, superimposed ores, stibnite and zinckenite, has been intimately connected with circulation of aqeuous, moderately saline fluids (15.5–23.5 wt% NaCl equiv.) upon epithermal conditions. Salinity of the aqueous fluids associated with tetrahedrite is clustered around 10 wt% NaCl equiv. Quartz from the latest, barite stage has precipitated from aqueous fluids enriched in divalent cations. These fluids are believed to be genetically linked with Triassic evaporite formations preserved in the region. Temperature-salinity diagrams constructed from microthermometry data indicate influx of diluted meteorite water in the stibnite, tetrahedrite and barite stages. Isotopic data are in accordance with model. The δ18O values between −9.3‰ and +1.5‰ have been derived for water in equilibrium with quartz, coexisting with sphalerite, tetrahedrite and barite, thus confirming the participation of isotopically lighter meteoric waters in the mineral-forming solutions. The (δ18O) values between +3.3‰ and +8.5‰ estimated for the water associated with the scheelite and arsenopyrite stages, are suggestive for the majority of metamorphic and/or magmatic water in the mineral-forming, CO2-rich solutions.

Cuprobismutite, kupčíkite, hodrushite and associated sulfosalts from the black shale hosted Ni-Bi-As mineralization at Čierna Lehota, Slovakia

Three sulphosalts from the cuprobismutite homologous series have been found in a hydrothermal Ni-Bi-As mineralization at Cierna Lehota (Slovakia). Kupcikite (second world occurrence) has a significant content of Pb (2.73 wt.%) and Fe (0.85 wt.%), with the structural formula (Cu 3.92 Fe 0.24 ) Σ4.16 (Bi 4.60 Pb 0.19 Ag 0.04 Sb 0.01 ) Σ4.84 S 9.58 . Hodrushite has a higher content of Ag (mean 1.27 wt.%), but less Fe (0.59 wt.%) and Pb (0.23 wt.%), with structural formula (Cu 7.79 Fe 0.38 ) Σ8.17 (Bi 11.34 Ag 0.43 Pb 0.04 Sb 0.02 ) Σ11.83 S 22.13 . Two varieties of cuprobismutite have the highest Ag content (3.8 and 2.3 wt.%), with Fe 0.6 and 0.2 wt.%, and Pb 0.1 and 6.7 wt.%, giving two formulas (Cu 7.42 Fe 0.47 ) Σ7.87 (Bi 12.56 Ag 1.55 Pb 0.02 ) Σ14.13 S 24.68 and (Cu 7.67 Fe 0.14 ) Σ7.81 (Bi 11.95 Pb 1.37 Ag 0.85 Sb 0.02 ) Σ14.19 S 24.13 . Chemical variations between these sulphosalts are compared with published data, that emphasizes the role of minor cations. Associated sulphosalts are described: aikinite, and Bi-rich tennantite (Bi up to 9.7 wt.%).

Mineralogical controls on antimony and arsenic mobility during tetrahedrite-tennantite weathering at historic mine sites Špania Dolina-Piesky and Ľubietová-Svätodušná, Slovakia

Abstract The legacy of copper (Cu) mining at Špania Dolina-Piesky and Ľubietová-Svätodušná (central Slovakia) is waste rock and soil, surface waters, and groundwaters contaminated with antimony (Sb), arsenic (As), Cu, and other metals. Copper ore is hosted in chalcopyrite (CuFeS2) and sulfosalt solid-solution tetrahedrite-tennantite {Cu6[Cu4(Fe,Zn)2]Sb4S13–Cu6[Cu4(Fe,Zn)2]As4S13} that show widespread oxidation characteristic by olive-green color secondary minerals. Tetrahedrite-tennantite can be a significant source of As and Sb contamination. Synchrotron-based μ-XRD, μ-XRF, and μ-XANES combined with electron microprobe analyses have been used to determine the mineralogy, chemical composition, element distribution, and Sb speciation in tetrahedrite-tennantite oxidation products in waste rock. Our results show that the mobility of Sb is limited by the formation of oxidation products such as tripuhyite and roméite group mineral containing 36.54 wt% Sb for samples where the primary mineral chemical composition is close to tetrahedrite end-member. Antimony K-edge μ-XANES spectra of these oxidation products indicate that the predominant Sb oxidation state is 5+. Arsenic and Cu are also hosted by amorphous phases containing 6.23 wt% Sb on average and these are intergrown with tripuhyite and roméite. Antimony in this environment is not very mobile, meaning it is not easily released from solid phases to water, especially compared to As, Cu, and S. For samples where the primary sulfosalt is close to tennantite composition, the oxidation products associated with tennantite relicts contain 2.43 wt% Sb and are amorphous. The variable solubility of the secondary minerals that have been identified is expected to influence mobility of Sb and As in near-surface environment.

Mineralogy and Geochemistry of the Nižná Boca Sb-Au Hydrothermal Ore Deposit (Western Carpathians, Slovakia)

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 g.cm-1 and 128-280°C, respectively. Mineralogia i geochemia hydrotermalnego złoża Sb-Au Nižná Boca (Zachodnie Karpaty, Słowacja) Złoże hydrotermalne Sb-Au, położone na SE od wsi Nižná Boca w Małych Tatrach, było eksploatowane do końca XIX wieku. Sporządzono mapy wystąpienia żył rudnych, a próbki pobrano z licznych hałd. W badaniach laboratoryjnych zastosowano mikroskopię w świetle odbitym, mikrosondę elektronową, dyfraktometrię rentgenowską, optyczną spektrometrię emisyjną, atomową spektroskopię absorpcyjną i analizę inkluzji ciekłych. Minerały kruszcowe są najczęściej zawarte w żyłach kwarcowo-węglanowych o przebiegu N-S, występujących w biotytowych granodiorytach-tonalitach typu I wieku waryscyjskiego (tzw. typ Ďumbierski). Paragenezy w złożu są zbliżone do innych przejawów mineralizacji tego samego typu w Niżnych Tatrach Ďumbierskich. Najstarszym jest etap kwarco-arsenopirytowy z pirytem, utworzony w temperaturach około 445°C. Następnie tworzyły się żyły kwarcowo-węglanowo-antymonitowe z zinkenitem, a po nich żyły kwarcowo-węglanowo-sfalerytowo-galenowe z boulangerytem i złotem. Złoto zawiera przeważnie 9-18% wag. Ag, niezależnie od współwystępujących z nim minerałów. Nie znaleziono złota innych generacji, chociaż nie można wykluczyć, że część jego ziaren powstała w wyniku remobilizacji złota ze struktury złotonośnego arsenopirytu. Zawartość Au w rudzie waha się w granicach 0,53-20,2 g·t-1, a Ag w granicach 0,9-31,2 g·t-1. Najmłodszymi paragenezami kruszcowymi w złożu są tetraedryt z chalkopirytem oraz baryt z hematytem. Ciekłe inkluzje zawarte w minerałach reprezentujących pierwszy etap powstania złoża mają zwykle rozmiary poniżej 3 μm i zawierają mniej niż 3,6% wag. CO2; ich zasolenie, gęstość i temperatury homogenizacji wahają się odpowiednio w granicach 2,7-16,35% wag. NaCl(eq), 0,85-1,03 g·cm-1 i 128-280°C.

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

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.

A NOTE ON THE CHEMICAL COMPOSITION OF NUFFIELDITE SOLID-SOLUTION FROM SULPHIDE MINERALIZATIONS IN THE WESTERN CARPATHIANS, SLOVAKIA

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.