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The gold deposits in the Latimojong Metamorphic complex are mainly hosted by metasedimentary rocks. The conditions of ore formation are estimated from fluid inclusion microthermometry, crush leach analyses on bulk samples and Raman spectroscopy on carbonaceous materials. The fluid inclusion assemblages are dominated by moderately saline H2O-rich fluids with minor aqueous-carbonic (CO2) inclusions. Fluid inclusions in quartz veins indicate that the temperature of hematite-quartz and sulfide-sulfosalt quartz veins does not exceed 250°C at 1 kbar pressure. Fluid inclusion assemblages in hematite-quartz veins and sulfide-sulfosalt quartz veins are characterized by a moderate salinity, in average 5.1 and 4.5 eq. mass% NaCl, respectively. Microthermometry from dolomite and barren veins indicates highly variable homogenization temperatures ranging from 165 to 387°C. Crush leach analyses on bulk samples reveal fluid compositions that are probably derived from mixing of different fluid sources. These results are comparable to orogenic gold deposits and give evidence for the influx of meteoric water during late-stage metal precipitation. Raman spectra of organic material in graphitic schist confirm that the region underwent blueschist- to greenschist facies metamorphism, followed by hydrothermal gold precipitation during decompressional uplift. We conclude that gold is retrograde and post-dates regional metamorphism.

Tailings of old mines often contain metals, which were not of economic interest or could not be recovered with the existing technology at the time of active mining. This is especially true for metals that often occur as by-products in Cu-Pb-Zn-(Ag-Au) ores as Sb, Mo, Ge, and In. A fundamental characterization of some tailings is presented in terms of their mineralogy and content of valuable metals which could be extracted to finance a possible remediation and improve the supply of the EU with critical metals. Tailings from active and abandoned mines in Serbia (Bor, porphyry Cu/Au; Krivelj, porphyry Cu/Au; Blagodat, hydrothermal Pb-Zn; Lece, epithermal Au; Rudnik, hydrothermal/skarn Pb-Zn) and North Macedonia (Sasa, Pb-Zn; Probištip, Pb-Zn; Bučim, porphyry Cu; Lojane, fault-bound vein-type low-temperature As, Sb, Cr at the contact of rhyolite and serpentinite) were studied. Analysis for major and trace elements used a multi-method approach (lithium borate fusion and ICP-MS/OES analysis, gravimetric analysis, instrumental neutron activation analysis, total digestion ICP-OES, infrared spectroscopy) with mineral identification by scanning electron microscopy. Concentrations of the major commodity elements (Cu, Pb, Zn, Au, Ag) varies within several orders of magnitude depending on mineralogy and ore type. Critical metals (Co, Ga, Ge, Sb) contents are low with some exceptions. Some tailings contain moderate to elevated potentially toxic element levels (As, Cd, Pb, Tl). For the sample from Probištip which yielded the highest valuable metal concentrations (>5000 ppm Pb, 4020 ppm Zn), a heavy mineral concentrate of the sand size fraction (0.06 mm to 0.5 mm) was produced and analyzed by SEM and LA-ICP-MS for additional rare phases and trace elements. In all tailings studied, additional milling would be needed to separate ore from gangue minerals. Increasing metal prices might facilitate feasibility studies for some of the localities in the future, despite the limited quantitative information about the characterized tailings.

Čukaru Peki is a recently discovered porphyry- high-sulfidation Cu-Au deposit located 5km south of the mining town of Bor in east Serbia. Three styles of mineralization are distinguished in the Čukaru Peki system: a high-sulfidation type with massive sulfides (named the Upper zone), a porphyry type (named the Lower zone) and a transition type (between porphyries and massive sulfides). This study investigates the concentration and distribution of trace elements in pyrite from these three mineralization zones of Čukaru Peki. The high-sulfidation pyrite contains elevated concentrations of V, Mn, Ni, Cu, As, Mo, Ag, Cd, In, Sn, Sb, Au, Hg, Tl, Pb and Bi, compared to pyrite from the porphyry zone. The porphyry zone pyrite contains elevated concentrations of Co and Se. The sample from the transition zone contains concentrations between the two other zones, with the exception of the relative enrichment of Co and Ag. This research also aims to separate different stages of ore deposition. The porphyry stage contains several types of veins: quartz A veins, quartz B veins, pyrite D veins, magnetite veins, purple anhydrite veins, sulfide veins and orange anhydrite veins. The high sulfidation stage also formed in several stages: pyrite1, pyrite-enargite veins, pyrite-covellite veins, pyrite2 veins and calcite-anhydrite veins. There are distinct differences between various vein generations found within each zone, notable examples are the enrichment of Se in quartz B veins pyrite and Cu in sulfide veins, compared to other veins from porphyry zone veins and the enrichment of several trace elements (Cu, Mo, Ag, Cd, In, Sn, Sb, Au, Hg, Tl, Pb and Bi) in pyrite from the Py-cov veins in comparison to the other high-sulfidation veins. The trace element data also indicates a change in fluid compositions; the earlier fluids responsible for the porphyry zone mineralization showing a slightly more magmatic fluid signature (higher Co/Sb and Se/As values) and the later high-sulfidation fluids bearing a more typical epithermal trace element signature, which indicates cooling and diluting of fluids. Some of the porphyry zone pyrite crystals (from B-type veins and Purple anhydrite-veins) contain elevated concentrations of elements attributed to the high-sulfidation zone (e.g. Cu, Ag, Cd, In, Sn, Pb and Bi), which suggests that these veins were affected by later high-sulfidation fluids.