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Secondary minerals of Pb-Zn Stan Terg skarn deposit, Kosovo - X-Ray Diffraction and Raman spectroscopy study

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Kołodziejczyk J. , Janicka U. , Prsek J.

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tom Vol. 38, no. 4

486--87

EN

Stan Terg deposit, one of numerous occurrences within the Vardar Zone on the Balkan Peninsula, is located in the north-eastern part of Kosovo. The formation of the deposit was controlled by metasomatic processes between carbonates and volcanic intrusive rocks. Ore bodies are located on the contact between Tertiary volcanic breccias, and Triassic metamorphic Trepca Series (represented by schists and carbonates). Significant number of ore precipitated from hydrothermal fluids in paleokarst cavities. Galena, sphalerite, pyrite, pyrrhotite and arsenopyrite are the main components of the primary ore assemblage (Forgan 1950, Schumacher 1950, Palinkas et al. 2013). The weathering zone is not well developed in the deposit. Development of weathering zone was stopped by tuff series overlaying the area after volcanic activity. Gossan occurs, but it is seldom (Forgan 1950). However, the circulating water through the karstic system could have dissolved sulphides, as well as neighboring rocks, which led to the precipitation and formation of secondary minerals on the galleries walls inside the mine. The aim of the study is identification and description of secondary minerals paragenesis that is present on the corridor walls inside the mine. The knowledge about this kind of secondary minerals may led to determination of weathering conditions in the deposit. Secondary minerals described in this study occur in minor amounts and should be regarded rather as a curiosity and as a supplement of knowledge about Stan Terg deposit. Samples were collected at 6 level of the mine. 20 samples were investigated using of X-Ray Diffraction (XRD) and 5 samples by Raman spectroscopy. Secondary minerals occur mainly in form of fine-grained crystals, dripstones or incrustations. Among them copiapite, roemerite, epsomite, bianchite, melanterite, rozenite and gypsum have been recognized. Copiapite is present in form of yellow and yellowish fine-grained crystals. It is most common secondary mineral in the mine. It occurs together with roemerite and epsomite. Roemerite, macroscopically not visible, occurs in minor amounts. Epsomite occurs in form of fine-grained, fibrous aggregates, crusts or dripstones. It exhibits white color, but may be also orange, if mixed with copiapite. Small amounts of bianchite were found (using XRD) within fine-grained crusts of epsomite. Melanterite occurs as crusts and stalactites. It builds clear phases or occurs together with other, yet not recognized minerals. A further study of melanterite is needed for successful characterization this additional phases. Rozenite was confirmed only by XRD. This mineral occurs in greenish-white fine-grained aggregates. Gypsum is a widespread mineral in the deposit. It occurs as single phases (with fibrous, fine-grained, needle-like or tabular crystals habit) or in lesser amounts with all other secondary minerals. Weathering of primary ore minerals is related to underground water circulating through karst cavities and fractures within the Stan Terg deposit. Recognized secondary minerals are being an effect of metal sulfides oxidation when oxygen and water are present in the environment. Highly soluble sulphates are formed in such condition. Copiapite, rozenite, melanterite, roemerite, bianchite may be caused by quickly oxidization of pyrite to aqueous Fe2+ and SO42- . The source of zinc in bianchite is sphalerite, whereas the presence of the magnesium in epsomite may be linked to Mg-reach carbonates. All of described minerals precipitated from the solution.

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New survey of lead and zinc ore mineralization in Republic of Kosovo

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Kołodziejczyk J. , Prsek J. , Qela H. , Asllani B.

Geology, Geophysics and Environment

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2012

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tom Vol. 38, no. 3

295--305

EN

Kosovo lead and zinc ore deposits are located in the Trepca Belt which extends for over 80 km. Several ore deposits occur in that belt, with the most important - Stan Terg (Trepca). Stan Terg deposit originating at the contact between volcanic breccias and carbonate rocks. Two different types of mineralization can be distinguished. The older one has origin related to pneumatolitic processes, when skarns were formed. The more recent one was formed by hydrothermal processes and has the largest economic importance. Over 70 minerals have been recognized in the Trepca deposit. Further mineralogical investigations will allow for the identification of other rare minerals.

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The paragenesis of silver minerals in the Pb-Zn Stan Terg deposit, Kosovo: an example of precious metal epithermal mineralization

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Kołodziejczyk J. , Prsek J. , Asllani B. , Maliqi F.

Geology, Geophysics and Environment

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2016

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tom Vol. 42, no. 1

19--29

EN

This study reports silver mineral association found recently in the Stan Terg lead and zinc mine, located in the Vardar zone (in northern Kosovo). The described mineralization comprises pyrargyrite (Ag3SbS3), freieslebenite (AgPbSbS3), high-Ag bearing tetrahedrite and freibergite ((Ag4+2xCu2−2x )[(Cu,Ag)4(Fe, Zn)2]Σ6Sb4S12S1−x with (0 < x < 1)); as well as native compounds (Electrum, composition of those minerals was confirmed by the electron microprobe. The freibergite from native silver is native antimony). The Ag-minerals occur in vuggs and cracks in a massive galena ore and have signs of the latest minerals, which precipitated in the deposit. The chemical of the Stan Terg deposit reveals zonality and contains between 13.91–20.28% of Ag. The high concentration of Ag in solutions is also indicated by relatively high silver content in Au-Ag alloy (electrum), which is between 47.02% and 73.19% of Ag. The Ag association is supposed to be an epithermal equivalent of precious metal mineralization, which could be located in the external part of the Stan Terg hydrothermal system. This association occurs in low temperatures, below 200°C. The Ag-minerals can be a part of epithermal veins from the external part of the Stan Terg hydrothermal system. Similarly to the other known Pb-Zn-Ag hydrothermal systems, the Ag association is related to the formation of the rhodochrosite banded ore and Ag-Au-Sb dominated mineralization.

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Mineralogical study of the Drazhnje Prospect (Kosovo) - preliminary report

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Kołodziejczyk J. , Asllani B. , Prsek J.

Geology, Geophysics and Environment

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2014

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tom Vol. 40, no. 1

91--92

EN

The mining activities took place in Kosovo since ancient times. The object of interest at these times was gold and silver ores. One of such old mining areas is located in north-east Kosovo, close to the Batlava Lake. Contemporary works include exploration activities and the goal of this research is to determine the features of mineralisation in that deposit. The name Drazhnje is used interchangeably with Cuka e Batllaves. In the close vicinity, there are known also several other base-metal ore bodies that may be of economic interest. During last years, an exploration gallery was built in Drazhnje, which gave an opportunity to collect mineralogical samples of ore from the upper part of the deposit. The Drazhnje prospect is located in area built of Paleozoic metamorphic complex, Jurassic sediments, ophiolite and Cretaceous flysch sediments. The volcanogenic-sedimentary complex of the Tertiary covers all the older rocks. The mineralisation in Drazhnje prospect is located within marbles, serpentinites and volcanic rocks. Mineralogical study is focused on the sulphide composition of the ore. Minimum two stages of mineralization can be distinguished. During the first one, pyrite, pyrrhotite, sphalerite and galena were formed. The younger stage comprises marcasite, chalcopyrite, arsenopyrite, stannite and Pb-Sb sulphosalts, mainly boulangerite. The gangue minerals are quartz and carbonates. Carbonates of different compositions belong to the youngest minerals in both stages. In the polished sections we have observed that stannite replaces sphalerite, and bournonite replaces galena. Galena is also being replaced by boulangerite. Evidence for boulangerite presence was confirmed by XRD method. Smithsonite was recognized as a main secondary mineral. It occurs as a greenish-to pinkish collomorphic coating on the surface of other minerals or it fills cavities in the ores. The Drazhnje deposit exhibits similarities to other Pb-Zn deposits in the area. The mineralization of stockwork character is hosted mainly by carbonates and its genesis is related to the volcanic activity. Preliminary data on ore chemistry indicate that the content of zinc is higher than content of lead, and is estimated at about 4% and 2%, respectively. In the other deposits of Kosovo, these values are reversed. High content of sulphosalts in the studied deposit, like bournonite and boulangerite, indicates that these minerals could be one of important bearers of lead in the Drazhnje deposit. Content of antimony reaches 0.3 wt. %, which could be correlated with relatively low content of lead (around 2 wt. %). During the field studies, we have confirmed that boulangerite is the most common lead mineral in the upper (reachable) part of deposit, whereas galena is not so common. It is worth to add that some amounts of galena have been replaced by bournonite. In comparison to samples from the other Kosovo deposits, we have noticed unusually high content of stannite, which was found in nearly all of the studied polished sections. Further exploration and start of extraction of the deeper parts of the deposit will allow collecting more samples that are necessery for future mineralogical and geochemical studies.

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Neoproterozoic pegmatite from Skoddefjellet, Wedel Jarlsberg Land, Spitsbergen: Additional evidence for c. 640 Ma tectonothermal event in the Caledonides of Svalbard

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Majka J. , Larionov A. N. , Gee D. G. , Czerny J. , Prsek J.

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tom 33

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nr 1