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New mineralogical and mineral-chemical data from the Stan Terg deposit, Kosovo, revealed the presence of abundant Bi-sulphotellurides associated with Bi-and Sb-sulphosalts and galena in pyrite-pyrrhotite-rich skarn-free ore bodies (ores without skarn minerals). The Bi-bearing association comprises Bi-sulphotellurides (joséite-A, joséite-B, unnamed phase A with a chemical formula close to (Bi,Pb) 2 (TeS) 2 , unnamed phase B with a chemical composition close to (Bi,Pb) 2.5 Te 1.5 S 1.5 ), ikunolite, cosalite, Sb-lillianite, members of the kobellite series and Bi-jamesonite. Compositional trends of the Bi-sulphotellurides suggest lattice-scale incorporation of Bi-(Pb)-rich module and/or admixture with submicroscopic PbS layers in modulated structures, or complicated Bi-Te substitution. Cosalite is characterized by high Sb (max. 3.94 apfu), and low Cu and Ag (up to 0.72 apfu of Cu+Ag). Jamesonite from this mineralization has elevated Bi content, from 0.85 to 2.30 apfu. The negligible content of Au and Ag in the Bi-sulphotellurides, the low content of Ag in Bi-sulphosalts, together with the lack of Au-Ag bearing phases in the mineralization, indicate either ore deposition from fluid(s) depleted in precious metals, or physico-chemical conditions of ore formation preventing Au and Ag precipitation at the deposit site. The temperature of initial mineralization may have exceeded 400 ºC as suggested by the lamellar exsolution textures observed in lillianite, which indicate breakdown textures from decomposition of hightemperature initial crystals. Non-stoichiometric phases among the Bi-sulphosalts and sulphotellurides studied at Stan Terg reflect modulated growth processes in a metasomatic environment.

Stannite group minerals (ferrokësterite and stannite) occur in small amounts in association with sulfides in hydrothermal Pb-Zn deposits in Kosovo. The chemical composition of sphalerite co-existing with Sn-bearing minerals has been investigated using laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS). Flat Sn-spectra suggest that Sn is bound in the sphalerite lattice or as nanoincluions. Sphalerite from Stan Terg, overgrown by ferrokësterite, contains the lowest Sn content (few ppm) and have been precipitated before Sn-enrichment in the fluids. The highest value of Sn (520 ppm) of Stan Terg sphalerite was obtained directly close to the ferrokësterite rim, and indicates a rapid increase of Sn in the hydrothermal fluids. Significantly higher values of Sn in sphalerite were obtained from other deposits: 1600 ppm (Artana), up to 663 ppm (Kizhnica), up to 2800 ppm (Drazhnje). Stannite-sphalerite geothermometry revealed the following ore-forming temperatures for the Kosovo mineralization: 240-390˝C for Stan Terg, 240-370˝C for Artana, >340˝C for Kizhnica, and 245-295˝C for Drazhnje. Sphalerite and stannite group minerals precipitated simultaneously during cooling from reduced hydrothermal fluids and under low-sulfidation fluid states. Fluctuations in physico-chemical fluid conditions are evidenced by the presence of stannite group minerals along growth zones in sphalerite and may be related to short interval of magmatic pulses during ore deposition.

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 (Ag 3 SbS 3 ), freieslebenite (AgPbSbS 3 ), high-Ag bearing tetrahedrite and freibergite ((Ag 4+2x Cu 2−2x )[(Cu,Ag) 4 (Fe, Zn) 2 ]Σ6Sb 4 S 12 S 1−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.

Kosovo lead and zinc ore deposits are located in the Trepça Belt which extends for over 80 km. Several ore deposits occur in that belt, with the most important Stan Terg (Trepça). 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 Trepça deposit. Further mineralogical investigations will allow for the identification of other rare minerals.