First zunyite-bearing lithocap in Greece: The case of Konos Hill Mo-Re-Cu-Au porphyry system

The Konos Hill prospect, represents a telescoped Mo-Re-Cu-Au porphyry system overprinted by a high sulfidation event. Porphyry mineralization is exposed in the deeper parts of the study area and comprises quartz stockwork veins, hosted in subvolcanic bodies of granodioritic composition. In the upper topographic levels, a significant hydrothermal alteration overprint predominates, and consists of silicification and various advanced argillic alteration assemblages, related to N-S and E-W trending faults. Further outwards, advanced argillic alteration gradually evolves into phyllic assemblages dominated by sericite. Zunyite, described for the first time from a lithocap in Greece, along with various amounts of quartz, alunite, APS minerals, kaolinite, pyrophyllite and diaspore constitute the major advanced argillic alteration minerals in the area. Mineral-chemical analyses revealed significant variance in the SiO2, F and Cl content of zunyite. Alunite supergroup minerals display a wide compositional range corresponding to members of the alunite, beudantite and plumbogummite subgroups. Diaspore displays almost stoichiometric composition with traces of TiO2, BaO, Ce2O3 and Nd2O3. The presence of the above-mentioned minerals indicates that low pH hydrothermal fluids flowing through fault planes resulted in extensive advanced argillic alteration in the area. The discovery of zunyite points towards an enrichment of volatile elements like F and Cl in the hydrothermal fluid, and helps to set constrains on the physicochemical conditions and the evolution of the mineralization and associated alteration

The Geology, Geochemistry, and Origin of the Porphyry Cu-Au-(Mo) System at Vathi, Serbo-Macedonian Massif, Greece

The Vathi porphyry Cu-Au ± Mo mineralization is located in the Serbo-Macedonian metallogenic province of the Western Tethyan Metallogenic Belt. It is mainly hosted by a latite and is genetically associated with a quartz monzonite intrusion, which intruded the basement rocks of the Vertiskos Unit and the latite, 18 to 17 Ma ago. A phreatic breccia crosscuts the latite. The quartz monzonite was affected by potassic alteration, whereas the latite was subjected to local propylitic alteration. Both styles of alteration were subsequently overprinted by intense sericitic alteration. M-type and A-type veins are spatially associated with potassic alteration, whereas D-type veins are related to the sericitic alteration. Three ore assemblages are associated with the porphyry stage: (1) pyrite + chalcopyrite + bornite + molybdenite + magnetite associated with potassic alteration; (2) pyrite + chalcopyrite related to propylitic alteration; and (3) pyrite + chalcopyrite + native gold ± tetradymite associated with sericitic alteration. A fourth assemblage consisting of sphalerite + galena + arsenopyrite + pyrrhotite + pyrite ± stibnite ± tennantite is related to an epithermal overprint. Fluid inclusion data indicate that the A-type veins and related porphyry-style mineralization formed at 390–540 °C and pressures of up to 646 bars

Lavrion smithsonites: A mineralogical and mineral chemical study of their coloration

Samples of smithsonite from the Lavrion mines are studied to determine the relationship between the colour of the mineral and the content of minor and trace elements and/or impurities. Among the trace elements found, responsible for the colouration are iron and manganese (?) (light yellow),and copper (blue,green). Copper presence is due to a ZnCO3-CuCO3 solid solution (up to 6.3 mol% CuCO3) and not to inclusions of copper minerals. In comparison, important inclusions are greenockite aggregates (yellow) and iron hydroxides (brown). In the most complicated cases, combinations of both trace elements and inclusions influence the final colour

Antimony’s Significance as a Critical Metal: The Global Perspective and the Greek Deposits

Antimony is widely acknowledged as a critical raw material of worldwide significance, based on its recognition by many countries. According to current projections, there is an anticipated increase in the demand for antimony in the forthcoming years. An issue of significant concern within the supply chain, which poses a substantial obstacle to sustainable development, is the global unequal allocation of abundant antimony resources. Most nations exhibited a high degree of dependence on a few countries for their net imports of antimony, resulting in a notable disruption and raising concerns regarding the supply chain. In most countries, antimony exploration and exploitation have been paused for a long period due to financial constraints associated with operations and environmental concerns. Nowadays, identifying additional antimony reserves, particularly in countries that heavily rely on new technologies and use significant amounts of antimony, is imperative and presents a pressing endeavor. Greece is recognized as one of the European Union member states with identified antimony deposits and a historical record of antimony exploitation. A thorough description, examination, and re-assessment of all existing data on the deposits and occurrences of antimony in Greece is presented. Most of Greece’s antimony deposits are related to hydrothermal processes, controlled by specific tectonic structures, and associated with Cenozoic magmatism. They are classified either as simple Sb-deposits, where the primary ore is a stibnite mineral, or complex polymetallic deposits with varying contents that include antimony minerals

A New Occurrence of Terrestrial Native Iron in the Earth's Surface: The Ilia Thermogenic Travertine Case, Northwestern Euboea, Greece

Native iron has been identified in an active thermogenic travertine deposit, located at Ilia area (Euboea Island, Greece). The deposit is forming around a hot spring, which is part of a large active metallogenetic hydrothermal system depositing ore-bearing travertines. The native iron occurs in two shapes: nodules with diameter 0.4 and 0.45 cm, and angular grains with length up to tens of µm. The travertine laminae around the spherical/ovoid nodules grow smoothly, and the angular grains are trapped inside the pores of the travertine. Their mineral-chemistry is ultra-pure, containing, other than Fe, only Mn (0.34–0.38 wt.%) and Ni (≤0.05 wt.%). After evaluating all the possible environments where native iron has been reported up until today and taking under consideration all the available data concerning the study area, we propose two possible scenarios: (i) Ilia's native iron has a magmatic/hydrothermal origin i.e., it is a deep product near the magmatic chamber or a peripheral cooling igneous body that was transferred during the early stages of the geothermal field evolution, from high temperature, reduced gas-rich fluids and deposited along with other metals in permeable structural zones, at shallow levels. Later on, it was remobilized and mechanically transferred and precipitated at the Ilia's thermogenic travertine by the active lower temperatures geothermal fluids; (ii) the native iron at Ilia is remobilized from deep seated ophiolitic rocks, originated initially from reduced fluids during serpentinization processes; however, its mechanical transport seems less probable. The native iron mineral chemistry, morphology and the presence of the other mineral phases in the same thermogenic travertine support both hypotheses

Mineralogy, Geochemistry and Fluid Inclusion Study of the Stibnite Vein-Type Mineralization at Rizana, Northern Greece

The stibnite mineralization at Rizana (Kilkis ore district; Serbo-Macedonian metallogenic province; northern Greece) occurs along a NE–SW-trending brittle shear-zone, which transects a two-mica and an augen-gneiss of the Vertiskos Unit. Barren Triassic A-type granites and satellite pegmatites and aplites, as well as Oligocene-Miocene plutonic, subvolcanic and volcanic rocks that are variably hydrothermally altered and mineralized, outcrop in the broader region. The mineralization appears as veins, discordant lodes and disseminations. Veins and discordant lodes exhibit massive and brecciated textures. Historic underground mining (1930s–1950s) produced 9000 t of stibnite ore, grading 40% Sb on average. The main ore mineral assemblage includes stibnite + berthierite + sphalerite + pyrite + chalcopyrite + native antimony and traces of wolframite, galena, tetrahedrite, marcasite, pyrrhotite, arsenopyrite, realgar, native arsenic and native gold. Quartz, minor barite and ankerite are the gangue minerals. Sericitization and silicification developed along the shear-zone, forming hydrothermal halos of moderate intensity in the two-mica gneiss. Locally, valentinite, goethite and claudetite are present due to the supergene oxidation of the stibnite mineralization. Bulk ore geochemistry shows enrichments in specific elements including As, Au, Cd, Se, Tl and W. Fluid inclusion microthermometry showed that the mineralization was formed under a limited range of temperatures and salinities. The fluids had low to slightly moderate salinities (6.6–8.1 wt% equiv. NaCl) with low homogenization temperatures (217–254 °C, with a maximum at 220 °C)

A Fluid Inclusion and Critical/Rare Metal Study of Epithermal Quartz-Stibnite Veins Associated with the Gerakario Porphyry Deposit, Northern Greece

The Gerakario Cu-Au porphyry deposit in the Kilkis ore district, northern Greece, contains epithermal quartz-stibnite veins on the eastern side of the deposit, which crosscut a two-mica gneiss. Metallic mineralization in these veins consists of stibnite + berthierite + native antimony + pyrite + arsenopyrite, and minor marcasite, pyrrhotite, chalcopyrite, löllingite, and native gold. Bulk geochemical analyses of the ore reveal an enrichment in critical and rare metals, including Ag, Au, Bi, Ce, Co, Ga, La, and Sb. Analysis of stibnite with LA-ICP-MS showed an enrichment in base metals (As, Cu, Pb), as well as weak to moderate contents of critical and rare metals (Ag, Bi, Ce, La, Re, Sm, Th, Ti, Tl). A statistical analysis of the trace elements show a positive correlation for the elemental pairs Ce-La, Ce-Sb, and La-Sb, and a negative correlation for the pair Bi-Sb. Fluid inclusions in the A-type veins of the porphyry-style mineralization show the presence of fluid boiling, resulting in a highly saline aqueous fluid phase (35.7 to 45.6 wt.% NaCl equiv.) and a moderately saline gas phase (14 to 22 wt.% NaCl equiv.) in the system H2O-NaCl-KCl at temperatures varying between 380° and 460 °C and pressures from 100 to 580 bar. Mixing of the moderate saline fluid with meteoric water produced less saline fluids (8 to 10 wt.% NaCl equiv.), which are associated with the epithermal quartz-stibnite vein mineralization. This process took place under hydrostatic pressures ranging from 65 to 116 bar at a depth between 600 and 1000 m, and at temperatures mainly from 280° to 320 °C.This article is published as Stergiou, Christos L., Vasilios Melfos, Panagiotis Voudouris, Lambrini Papadopoulou, Paul G. Spry, Irena Peytcheva, Dimitrina Dimitrova, and Elitsa Stefanova. "A Fluid Inclusion and Critical/Rare Metal Study of Epithermal Quartz-Stibnite Veins Associated with the Gerakario Porphyry Deposit, Northern Greece." Applied Sciences 12, no. 2 (2022): 909. doi:10.3390/app12020909. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/)