No description available.

The polymetallic carbonate-replacement prospect at Piavitsa is part of the ore-forming system of the Stratoni Fault Zone within the Kassandra mining district in northeast Greece. This district constitutes the southern segment of the Serbo-Macedonian belt, a promising region for the exploration of precious and critical metals in Greece. This master thesis is framed within the X-MINE project under the Horizon 2020 program. Three main objectives are defined: (1) to characterize the mineralization at Piavitsa utilizing reflected light microscopy, microprobe, and laser-ablation inductively coupled mass spectrometry (LA-ICP-MS), and (2) to evaluate the contributions of the scanning GeoCore X10 (XRF-XCT) technology to the understanding of the ore, and (3) to assess potential environmental impacts. At Piavitsa, an early base-metal assemblage, composed of brecciated sphalerite and As-rich pyrite, is infilled and overprinted by an assemblage of As-poor to moderately-rich pyrite, alabandite, and Mnrich sphalerite. The latter two are corroded and replaced by Mn-rich carbonate. Fractures and interstices are infilled by a late assemblage of Ca-Mn-Mg carbonate, galena, As-poor pyrite, tetrahedrite-tennantite, and in the periphery of the orebody, seligmannite-bournonite and kesterite.  Based on absolute elemental concentrations obtained by in situ LA-ICP-MS, the mineral hosts (primary; secondary) are defined as: pyrite (Fe, Co, Ni, and Au; As), sphalerite (Zn, Ga, Ge, Cd, Sn; Mn), galena and bournonite (Pb, Se, Te, Tl, and Bi; Ag, Sb), alabandite (Mn; Cd and Sb), and tetrahedrite (Cu, As, Ag, and Sb). In cocrystallized assemblages, some differences are observed. In pyritetetrahedrite asemblages, tetrahedrite mainly hosts As and Au, instead of pyrite, whereas in sphaleritealabandite assemblages, alabandite is the host of Mn, As, Ag and Sb and sphalerite, of Cd and Sn. Three concentrates are produced from the current mining operations of Hellas Gold in the Stratoni area, e.g, Mavres Petres Zn-Pb mine. From LA-ICP-MS, it is inferred that a sphalerite concentrate from the Piavitsa ore would contain Ga (peripheral ore: 150 ppm; main ore: 10-40 ppm), Sn (peripheral ore: 800-1500 ppm; main ore: 25-230 ppm), and Cd (1600-4000 ppm). The galena concentrate would contain concentrations of Ag (1300-1700 ppm), Se (50 ppm), Sb (1200-1600 ppm), and Te (85-210 ppm). The pyrite concentrate would contain Au (0.5-24.5 ppm) but would be devoid of other economical trace elements. The values given here consider 100% purity, instead of 80-90% reported in previous studies. The GeoCore X10 technology provides a good indication of measurable elements. (>0.01 wt.%), including Mn, Fe, Cu, Zn, and Pb; As, Sb and Sn. Moreover, it helps to quickly identify the main ore and gangue minerals and their distribution in the deposit. The distinction between the ore and gangue minerals can be easily achieved based on the difference in their X-ray attenuation. It is worth highlighting that mineralogical info obtained by other analytical methods is still essential to validate the outputs of the instrument and to improve the interpretations drawn from them. Regarding the environmental impacts of mining the ore, the potential for acid generation and pollutant mobilization are low due to the carbonate-rich matrix. The mining poses low radioactivity risks due to the low concentration of radionuclides. Establishing a pollutants baseline and monitoring the surrounding water bodies and soils is highly recommended to reduce overlooked environmental impacts.