Platinum-group element and gold contents in the Skouries porphyry copper deposit, Chalkidiki Peninsula, northern Greece

Critical Factors Controlling Pd and Pt Potential in Porphyry Cu–Au Deposits: Evidence from the Balkan Peninsula

“…It is consistent with the abundance of magnetite in all porphyry Cu-Au-Pd deposits of the Balkan Peninsula [14][15][16][17][18][19]. In contrast, "reduced" porphyry Cu-Au deposits, lacking primary hematite, magnetite, and sulphate minerals (anhydrite), contain abundant pyrrhotite, and are relatively Cu-poor, but Au-rich deposits [6].…”

“…Such an association of the palladium telluride, merenskyite, as the main PGE mineral in porphyry Cu-Au-Pd-Pt deposits, is considered to be of genetic significance and an important factor for the recovery of Pd and Pt as by-products. Relatively high Pd content in the major vein-type mineralization of Skouries has been documented by the analysis of a composite drill hole sample (~15 kg) showing 76 ppb Pd and 5000 ppm Cu [14,15].…”

“…These precious metals belong to the platinum-group elements (Os, Ir, Ru, Rh, Pd and Pt or platinum-group elements (PGEs)), which are the most valuable elements, of strategic importance, due to their growing use in advanced technologies (medicine, electronics) and automobile catalyst converters. Although they are traditionally associated with mafic-ultramafic complexes, significant Pd and Pt contents were described in certain alkaline porphyry deposits, such as the Cordillera of British Columbia (Copper Mountain, Galore Creek), Allard Stock, La Plana Mountains and Copper King Mine in USA [12,13], Skouries porphyry deposit, Greece [14,15], Elatsite, Bulgaria [16][17][18][19], Santo Tomas II in the Philippines [20,21] and elsewhere ( Figure 1). …”

Gibbs Free Energy of Formation for Selected Platinum Group Minerals (PGM)

“…The calculated Gibbs free energy values may contribute to better understanding of the knowledge provided by geochemical data, mineral chemistry and structure relationships (microscopic scale) as they are obtained from the investigation of PGE/PGM in nature [43][44][45][46][47][48][49][50]. The more negative Gibbs free energy values for the RuO 2 compared to those for the RuS 2 , in the range of temperature lower than 500˝C (Table 4, Figure 5), seems to be in good agreement with the common transformation of laurite to oxides/hydroxides in small chromite occurrences [13,48], in placer deposits [49], in the oxidized zone of the Great Dyke of Zimbabwe layered intrusion [50], in laterite deposits [51][52][53] and elsewhere.…”

“…In addition, the earlier deposition of (Pt, Pd)S compared to (Pd, Pt)Te 2 , since (Pt, Pd)S is dominant in the UG2chromitite unit (Bushveld), which is located at a lower stratigraphic level compared to the Merensky Reef, where (Pd, Pt)Te 2 are dominant PGM [18,43], seems to be consistent with the more negative free energy values in the former than in the latter ( Table 1). [44][45][46][47], may be related to fS 2 , fTe 2 and temperature, as well [41,42]. Assuming that the elevated values of the Pd/Pt ratios, the extremely low Cr contents (<1 ppm) in high Cu-Pd-Pt-grade ores, negative correlation between Cr content and the Pd/Pt, δ 18 O values in porphyry deposits of the Balkan Peninsula suggest genesis from more evolved mineralized fluids in porphyry Cu-Au-Pd-Pt deposits [44][45][46][47], the dominance of (Pd-Pt)-tellurides versus (Pt, Pd)S may be related to fS 2 , fTe 2 and temperature variation.…”