Nb-Ta-Ti-bearing oxide minerals (Nb-Ta-bearing rutile, columbite-group minerals, W-bearing ixiolite) represent the most common host in high-F, high-P Li-mica granites and related rocks from the Geyersberg granite stock in the Krušné hory/Erzgebirge Mts. batholith. The Geyersberg granite stocks forms a pipe like granite stock composed of fine- to middle-grained, porphyritic to equigranular topaz- Li mica granites, containing up to 6 vol. % of topaz. Intrusive breccias on the NW range of the granite stock are composed of mica schist- and muscovite-gneiss fragments enclosed in fine-grained aplitic granite. Granites are partly greisenised, mainly along of steeply dipping NW-SE, and NE-SW trending faults. Quartz-Li-mica-topaz greisens are mineralised by cassiterite, arsenopyrite, wolframite and molybdenite. The high-F, high-P Li-mica Geyersberg granites, which represent the youngest granite intrusions in the Western and Middle Krušné Hory/Erzgebirge plutons, are highly fractionated S-type granites (ASI = 1.2–1.5) with Nb/Ta ratio = 0.74–1.12 and depletion in high-field-strength elements (HFS). Columbite group minerals occur usually as anhedral grains that display patchy zoning. These minerals are represented by columbite-(Fe) with Mn/(Mn+Fe) ratio ranging from 0.07 to 0.32. The rare Fe-rich W-bearing ixiolite occurs as small needle-like crystals. The ixiolite is Fe-rich with relatively low Mn/(Mn + Fe) and Ta/(Ta + Nb) values (0.10–0.15 and 0.06–0.20 respectively). Owing to the high W content (19.8–34.9 wt. % WO₃, 0.11–0.20 apfu), the sum of Nb + Ta in the ixiolite does not exceed 0.43 apfu. The Ti content is 1.7–5.7 wt. % TiO₂ and Sn content is relatively low (0.3–4.1 wt. % SnO₂)

The SART process (SP) has been successfully implemented in gold cyanidation plants to address issues associated with high cyanide-soluble copper content the ores. However, this process could produce a relatively low grade precipitate, descreasing the sale price, when gold plants have high zinc and copper content in their solutions. A potential option in this case would be use of a two-stage SART process (TSSP) to produce separate zinc and copper precipitates. The additional equipment involved with this process would increase the capital cost, thereby generating concerns about the optimal range of metal contents that could justify this option. This study presents a methodology to quantify the feasible range of Cu/Zn concentrations that would justify a two-stages SART process. The study is based on a thermodynamic model and a simple economic evaluation. Results show the TSSP is preferred when the Cu/Zn ratio ranges between 0.2 and 1.5 with copper concentration higher than 500 mg/L. The TSSP appears to be a viable option to consider for gold plants having concentrations of copper and zinc higher than 500 and 350 mg/L respectively.

Zunyite is a rare F- and Cl- bearing mineral related to advanced argillic alteration zones of porphyry/epithermal style mineralization and is considered as a pathfinder mineral towards high-grade Au ores. We report here the first occurrence of zunyite along with alunite, quartz, APS minerals, diaspore, pyrophyllite and kaolinite in the metallogenic province of Western Thrace.

The Konos Hill prospect in Western Thrace comprises a telescoped porphyry Mo-Re-Cu-Au system, overprinted by high-sulfidation mineralization. In low topographic levels, porphyry-style mineralization is exposed and comprises pyrite-chalcopyrite-bornite-molybdenite-rheniite-bearing quartz-stockwork. Host rocks are subvolcanic bodies of granodioritic composition that have suffered pervasive sericitic alteration. High-sulfidation epithermal-style alteration occupies the higher topographic levels and has caused significant overprinting of the porphyry-style mineralization and alteration. It consists of silicified zones related to N-S and E-W trending faults, which grade outwards to advanced argillic alteration assemblages. These assemblages are characterized by abundant alunite and quartz, with minor presence of diaspore, APS minerals, kaolinite, pyrophyllite and zunyite.

Zunyite forms euhedral crystals that reach in size up to 300μm. They sometimes include minor quartz and are associated with alunite, APS minerals and pyrophyllite. EPMA data revealed variations in the F and Cl content of zunyite, that range between 3.62-6.54 wt.% and 2.65-3.15 wt.% respectively. Alunite supergroup minerals display a wide compositional range and are represented by members of the alunite, beudanite and plumbogummite subgroups. Alunite and natroalunite constitute the most common advanced-argillic alteration minerals and are found in both quartz+zunyite and quartz+diaspore+pyrophyllite assemblages. Available mineral-chemical data favor the existence of compositions that cover a complete solid-solution series between Na- and K-rich varieties. Common mode occurrences comprise euhedral, tabular-shaped and rarely pseudocubic crystals. APS minerals are usually found as pseudocubic crystals forming the cores of tabular alunites. Analyzed compositions comprise woodhouseite (Sr-, Ce- and Sr-Ce- rich members were found). Diaspore forms aggregates of euhedral, coarse-grain crystals scattered in strongly silicified rock. Finally, pyrophyllite when present, forms acicular aggregates in the matrix along with diaspore and quartz.

Available data suggest that the formation of the studied advanced argillic alteration assemblages is hypogene and due to ascending magmatic fluids released by the subvolcanic bodies. Mineralogical variances in the different assemblages may reflect distinct degrees of hydrothermal alteration. Co-existence of zunyite, APS minerals and pyrophyllite could be used to set constraints on the physicochemical conditions of formation of the assemblage, as the volatile-rich nature of the minerals reflects a narrow range of pH and temperature in hydrothermal systems.

The Lavrion ore district, located about 50 km southeast of Athens (Greece), contains a variety of ore types including porphyry Mo-W, skarn Fe-Cu-Bi-Te, carbonate-replacement Pb-Zn-Cu-Ag±Au-Bi and vein-type Pb-As-Sb-Ag and Pb-Ni-Bi-Au (Solomos et al. 2004; Voudouris et al. 2008; Bonsall et al. 2011; Kolitsch et al. 2015). Mineralization was synchronous to the intrusion of a Miocene granodiorite body in the footwall of the Western Cycladic Detachment System and related felsic dikes and sills within marbles and schists, which locally cross-cut the detachment. Carbonate-sericite altered microgranodioritic dikes and sills at Kamariza are crosscut by porphyry-style quartz-sericite-calcite stockworks hosting pyrrhotite, pyrite, arsenopyrite, chalcopyrite and sphalerite (e.g. the same metallic minerals present in the carbonate-replacement and vein ores). The dikes and sill display enrichment in Ni (up to 220 ppm), Cu (up to 175 ppm), As (up to 510 ppm), Mo (up to 6 ppm) and Pb (up to 830 ppm), as measured by ICP-MS. The Ni-Bi-Au association at the Clemence mine in Kamariza is a vein-type mineralization developed at the contact between marbles and schists. The mineralization also expands in the marbles unit, forming carbonate-replacement bodies. It consists of native gold and bismuthinite intergrown with gersdorffite, enclosed in galena. Bulk ore analyses reveal Au and Ag grades exceeding 100 ppm, Pb and Zn > 1 wt. %, Ni up to 9700 ppm, Co up to 118 ppm, Sn > 100 ppm and Bi > 2000 ppm. New mineralogical and mineral-chemical data from the Ni-Bi-Au association suggest gold deposition with oscillatory zoned gersdorffite following initial deposition of pyrite and arsenopyrite. Oscillatory zoning in gersdorffite is related to variable As, Ni and Fe contents, indicating fluctuation of arsenic fugacity in the hydrothermal fluid. Chalcopyrite, tennantite and enargite rimming gersdorffite suggest an evolution towards higher sulfur fugacity in the mineralization with time. Stannite enclosed in pyrite and native antimony enclosed in galena are decribed here for the first time in the Clemence ore assemblage. At the ‘km-3’ locality, the Ni sulfides and sulfarsenides, vaesite, millerite, ullmannite and polydymite, are enclosed in gersdorffite and/or galena. At this location mineralization occurs in the form of calcite and galena veins crosscutting and cementing brecciated marbles, within the detachment fault. Mineralization is enriched in Mo (up to 36 ppm), As and Ni (both >1 wt. %), Co (up to 1290 ppm), whereas other elements occur in lesser amounts: Te (up to 2 ppm), Sn (up to 8.5 ppm), Bi (up to 1.3 ppm). Gersdorffite at ‘km-3’ is homogenous and contain less Fe (up to 2 wt. %) than that from the Clemence mine (up to 9 wt. %), probably related to lower temperatures of their formation. The geochemical and mineralogical data from this study support previous models for a magmatic contribution of metals to the ore system, although a remobilization from previous mineralization and/or country rocks cannot be ruled out.

A common feature of precious metal mineralization in Greece is the close relationship between gold and silver with other trace minerals incorporating bismuth, tellurium and selenium in their structure. These minerals can be considered as pathfinders for gold as they may guide exploration to discover distinct types of gold-bearing ores. Primary gold mineralization in Greece can be subdivided in three groups regarding the mineral associations with gold: (A1) mineralization where native gold and Au-Ag tellurides accompany either Bi-sulfosalts, native Bi and reduced-type Bi-sulfotellurides (joséite-A, joséite-B, pilsenite) at Koronouda, Laodikino/Kilkis area, Stanos, Olympias-Stratoni and Fissoka at Chalkidiki area and Angistron Mt/W. Rhodope), or (A2) accompany Bi-sulfosalts with oxidized-type Bi-sulfotellurides (e.g. tetradymite and tellurobismuthite) typical for Aberdeen, Palea Kavala, Thasos island, as well as for the calc-alkaline and alkaline-hosted porphyry and epithermal deposits/prospects in western Thrace, Limnos island and Skouries; (B) deposits which lack tellurides but include Bi-sulfosalts and native gold (e.g. the carbonate replacement deposit of Lavrion, the porphyry-Cu-Mo-Au deposits of Maronia and Stypsi, Lesvos Island, and the intrusion-related Kimmeria Cu-Mo-Au deposit); and (C) deposits/prospects where native gold and Au-Ag-tellurides and other base metal tellurides are abundant and Bi-tellurides and Bi-sulfosalts are missing (the metamorphic rock-hosted quartz veins at Panormos/Tinos and Kallianou/Evia Islands, and the epithermal shallow submarine mineralization at Milos). Bismuth and tellurium are considered to be derived from magma and recognition of bismuth sulfosalts and bismuth tellurides, as well as of various types of base (and precious) metal tellurides in the mineralization, is a strong evidence of magmatic-hydrothermal contribution and of adjacent concealed intrusives (e.g. Perama Hill and Pefka deposits are cases where no granitoids are exposed). The absence of bismuth minerals and the presence of precious and base metal tellurides (as is the case for Milos, Tinos and Evia islands) may still suggest magmatic contributions but in more distal setting from a buried granitoids at depth. Selenium (and/or bismuth) bearing galena and Se-bearing bismuth chalcogenides present at Kimmeria intrusion-hosted veins, at Lavrion, as well as in several porphyry-epithermal deposits in northern Greece (e.g. Kassiteres-Sapes, Pagoni Rachi, Perama Hill, Pefka and Skouries) are indicative of high-temperature, initial stages of ore deposition from magmatic-hydrothermal fluids, and proximity to porphyry mineralized centers. When recognized in a mineralization as an accessory mineral, Se-bearing galena could guide exploration towards unexposed granitoids. Bornite and molybdenite are present in the potassic and sericitic alteration zones of Skouries and Pagoni Rachi porphyry deposits, where they are intimately associated with native gold and gold-silver tellurides. However bornite may also occur in intermediate-sulfidation epithermal veins at Kassiteres-Sapes and Pagoni Rachi areas and molybdenite at Stanos and Syros Island without any obvious relationship to a granitoid. Both minerals can be applied for discovery of high temperature mineralized zones in the system.