Polymetallic Cu-Bi-(Pb-Zn-Co-Ag) mineralization of the Perin Potok locality near Bor, Serbia

Complex polymetallic Cu-Bi-(Pb-Zn-Co-Ag) mineralization of the Perin Potok locality occurs as disseminations and fine nests in quartz-ankerite-(sericite) veins. The veins are located in metamorphic rocks of the outer contact zone of the Variscan Gornjane Granitoid. The mineralization consists of (in decreasing abundance): chalcopyrite, aikinite, bismuth, galena, Ag,Bi-bearing tetrahedrite, sphalerite, cobaltite and an unnamed Bi2Te mineral. All these phases form distinctive exsolutions and intergrowths and they simultaneously precipitated from a very complex hydrothermal fluid. Silver shows elevated contents in tetrahedrite (3.3-4.4 wt. % Ag), galena (0.9-1.1 wt. % Ag) and in the unnamed Bi2Te mineral (0.9 wt. % Ag). Such high Ag concentrations can imply that Ag minerals could be also present. Minor amounts of rutile showing fine intergrowths with sericite also occur in this paragenesis. This is W-bearing rutile that shows zoning caused by up to 2.2 wt. % W. The studied mineralization is probably genetically related to the Variscan Gornjane Granitoid, although the possibility of derivation from the metamorphic basement should be also taken into account. [Projekat Ministarstva nauke Republike Srbije, br. OI176016

Crystallography and Surface Oxidation of Stoichiometric Arsenopyrite from Šumadija-Kopaonik Pb-Zn/Polymetallic Ore District (Serbia)

The behaviour and stability of arsenopyrite largely depend on its crystal structure, but studies of crystallography and structural defects are scarce. For clarification, we investigated a series of natural arsenopyrite crystals from the polymetallic Pb-Zn-(±Cu,Ag,Au,Sb,Bi,W) Šumadija-Kopaonik ore district (Serbia) by powder X-ray diffraction (XRPD). Among them, samples from the Drenjak gold mineralisation showed near-stoichiometric FeAsS composition and were further investigated by conventional and high-resolution transmission electron microscopy methods. TEM revealed abundant planar crystallographic defects and epitaxial surface oxide layer formation upon air exposure. Our findings present the fundamental work on the prototype arsenopyrite structure and have further implications for studies on ion incorporation into FeAsS structure and its environmental stability and oxidation mechanisms as a source of anthropogenic As release into the environment

Valorization of complex polymetallic ores in the Čoka Marin deposit

The complex polymetallic deposit 'Čoka Marin' has been explored over many years. Due to its complex mineral composition and primarily a high content of precious metals it represents a particular challenge for mining experts. Over the past few years preparatory works for the ore body Čoka Marin-1 have been intensified to provide necessary conditions to excavate and prepare the ore in the Majdanpek Flotation Plant for further metallurgical processing of the collective concentrate. The new methods that were investigated to smelt the collective copper concentrate with precious metals opened new possibilities for ore valorization. This paper presents a detailed analysis of various ore excavation methods that may be applied in the 'Čoka Marin' Deposit along with the stability analysis. Further on, the results of detailed mineralogical analysis are given to show particularly the manner in which the precious metals appear. Finally, the paper presents the research results and different possibilities of ore concentration flotation processes

Crystal structure and chemical composition of ludwigite from Vranovac ore deposit (Boranja Mountain, Serbia)

The crystal structure of ludwigite from Vranovac ore deposit (Boranja Mt., Serbia) was refined using the X-ray powder diffraction (XRPD) Rietveld method in the space group Pbam to a final RB=7.45% and RF=5.26%. It has the unit cell dimensions of: a=9.2515(2) Å; b=12.3109(2) Å; c=3.03712(7) Å; and V=345.91(1) Å3. The calculated distances and angles are mostly in good agreement with the Mg2+-Fe2+ substitutions across the M(1) and M(3) sites, as well as with the Fe3+-Al3+ replacement in the M(4) site. However, the mean observed M(2)-O distance is considerably shorter than prescribed, due to a slight increase of the Fe3+ content in the M(2) site. Such replacement was compensated by slight increase of the Fe2+ content in the M(4) site, resulting in the (Mg1.48Fe2+0.46Fe3+0.05Mn0.02)2.01(Fe3+0.94Fe2+0.04Al0.02)1.00B1.00O5 composition. The formation temperature was estimated to be about 500–600°C. The influences of the various chemical compositions to the crystallographic parameters, M-O distances, M(3) and M(4) sites shift, distortion parameters and estimated valences, were also studied and compared with other reference samples

A review of Pb-Sb(As)-S, Cu(Ag)-Fe(Zn)-Sb(As)-S, Ag(Pb)-Bi(Sb)-S and Pb-Bi-S(Te) sulfosalt systems from the Boranja orefield, West Serbia

Recent mineralogical, chemical, physical, and crystallographic investigations of the Boranja orefield showed very complex mineral associations and assemblages where sulfosalts have significant role. The sulfosalts of the Boranja orefield can be divided in four main groups: (i) Pb-Sb(As)-S system with ±Fe and ±Cu; (ii) Cu(Ag)-Fe(Zn)-Sb(As)-S system; (iii) Ag(Pb)-Bi(Sb)-S; (iv) and Pb-Bi-S(Te) system. Spatially, these sulfosalts are widely spread, however, they are the most abundant in the following polymetallic deposits and ore zones: Cu(Bi)-FeS Kram-Mlakva; Pb(Ag)-Zn-FeS2 Veliki Majdan (Kolarica-Centralni revir-Kojići); Sb-Zn-Pb-As Rujevac; and Pb-Zn-FeS2-BaSO4 Bobija. The multi stage formation of minerals, from skarnhydrothermal to complex hydrothermal with various stages and sub-stages has been determined. All hydrothermal stages and sub-stages of various polymetallic deposits and ore zones within the Boranja orefield are followed by a variety of sulfosalts. [Projekat Ministarstva nauke Republike Srbije, br. OI-176016: Magmatism and geodynamics of the Balkan Peninsula from Mesozoic to present day: Significance for the formation of metallic and non-metallic mineral deposits

New Constraints on the Main Mineralization Event Inferred from the Latest Discoveries in the Bor Metallogenetic Zone (BMZ, East Serbia)

This study aims at better constraining the link between magmatism and metallogeny in the south-easternmost sector of the Bor Metallogenetic Zone (BMZ), where the world-class copper and gold deposit of Čukaru Peki was recently discovered. The obtained U/Pb zircon ages confirm the earlier knowledge that the major Cu–Au porphyry and epithermal mineralization in the BMZ is genetically related to the first volcanic phase (‘Timok andesite’; 85–90 Ma). However, the data also suggest that during this phase, two subgroups of andesite porphyry were formed; they are named volcanic phase 1A (V1A) and volcanic phase 1B (V1B). The V1A andesite (89–90 Ma) is plagioclase-hornblende phyric, holocrystalline and ubiquitously hydrothermally altered and/or mineralized, whereas the V1B (85–86 Ma) is hornblende-plagioclase phyric, holo- to hypocrystalline, fresh, and non-mineralized. According to our simplified model, the contrasting productivity of the V1A and V1B is explained by fluctuations during AFC (assimilation-fractional crystallization) processes of water-rich parental magma, which have controlled the order of crystallization of hornblende and plagioclase in the V1A and V1B andesite

Diversity and biodeteriorative potential of bacterial isolates from deteriorated modern combined-technique canvas painting

Cultivable bacteria colonizing deteriorated modern painting on canvas were identified in order to evaluate their potential to deteriorate organic and inorganic painting's constituents. Different sampling and cultivation strategies enabled isolation of bacteria belonging to nine genera of Firmicutes, Proteobacteria, and Actinobacteria phyla. Overall predominant bacteria were species of Bacillus (51%) and Staphylococcus (36%) genera. Representatives of six different genera (Staphylococcus, Acinetobacter, Agrococcus, Janibacter, Rhodococcus, and Stenotrophomonas) were isolated for the first time from deteriorated canvas. Almost all isolated bacteria produced proteases, esterases, and lipases, which may be involved in deterioration of painting's binders and media. Bacteria expressing endocellulase were reported. Selected bacterial isolates were tested for ability to deteriorate six pigments. All tested isolates were able to grow in the presence of Ivory black, Red and Yellow ochre, as a sole source of phosphate and iron, inducing their fading. The majority of isolates induced solubilization of Zinc white and Cobalt deep green. Cadmium red pigment that inhibited the growth of a half of isolates proven to be the most toxic pigment. Isolated bacteria were equipped with all required metabolic prerequisites in order to pose a threat to the painting as a whole