Distribution of Technology-Critical Elements in the Trepça Mine (Kosovo): Insights from Mineralogical, Geochemical and Microstructural Analyses

This study investigates the presence of Technology-Critical Elements in the Trepça mine (Stan Tërg, Mitrovicë), representing the first assessment of their distribution within this mining district. Samples were collected in all ore bodies (three samples per ore body) in horizons VIII-XI. Mineralogical, geochemical and microstructural characterization was performed using X-ray diffraction (XRD), Inductively Coupled Plasma Mass-Spectrometry (ICP-MS), and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX). The analyses confirmed the presence of several Technology-Critical Elements, especially Bi, Co, Ge, W, Ga, In, Te and Sb, whose distribution, correlation with mineral phases and structure were also identified. XRD enabled the identification of mineral phases while SEM-EDX provided structural and morphological characteristics of these mineral phases. The ICP-MS results indicate significant variability in the distribution of these elements. Bi reached extremely high concentrations (up to 2570.68 ppm in ore body 136), well above the method detection limit (MDL = 0.01 ppm), whereas Co exhibited elevated yet moderate concentrations that increased with depth, indicating a depth-dependent rise in concentration. V, W, Sb and Sn also exhibited elevated concentrations. Peak enrichment levels were observed for Bi (up to 2750 ppm) in Horizon IX, Sb (up to 504 ppm) in Horizon XI, W (up to 308 ppm) in Horizon VIII, and In (up to 34,730 ppm) within selected ore bodies, indicating pronounced vertical geochemical zonation. The results demonstrate that selected ore bodies represent significant potential sources of Technology-Critical Elements, supporting future resources and strategic raw material assessment within the Trepça mining district.