Neoproterozoic pegmatite from Skoddefjellet, Wedel Jarlsberg Land, Spitsbergen: Additional evidence forc. 640 Ma tectonothermal event in the Caledonides of Svalbard: Neoproterozoic (c. 640 Ma) amphibolite facies metamorphism and deformation have been shown recently to have affected the Isbjørnhamna and Eimfjellet Complex of Wedel Jarlsberg Land in southwestern Spitsbergen. New SHRIMP zircon U-Pb andin situelectron microprobe monazite and uraninite U-Th-total Pb ages are presented here on a pegmatite occurring within the Isbjørnhamna metasedimentary rocks. Although the dated zircons are full of inclusions, have high-U contents and are metamict and hence have experienced notable Pb-loss, the new Cryogenian ages are consistent with the age of regional metamorphism of the host metasediments, providing additional evidence for a clear distinction of the Southwestern Province from the other parts of the Svalbard Caledonides.

Agate samples collected from the vicinity of Asni and Agouim (Western Atlas, Morocco) were investigated using microscopic observations supported by Raman micro-spectroscopy. The agates are marked by the presence of various microtextures typical of epithermal vein deposits, including jigsaw-puzzle, feathery, and lattice-bladed. The first two indicate that the formation of agates was likely marked by recrystallization of metastable silica phases (i.e., opaline silica or massive chalcedony). The presence of lattice-bladed (after barite and calcite) quartz may be, in turn, ascribed to the boiling-related conditions that could have triggered the formation of abundant copper and iron sulfides found within silica matrix. Additionally, the local occurrence of growth lines (so-called Bambauer quartz) and intergrowth of length-slow and length-fast chalcedony are linked to the variations of physico-chemical conditions during rock formation (alkaline-acidic). According to Raman spectroscopy, silica matrix of the agates is made of α-quartz with a local admixture of moganite (from 0.0 up to 78 wt.%), but also contains numerous solid inclusions of hematite, celadonite, as well as poorly-organized carbonaceous material and rutile. These phases were likely emplaced during low-temperature hydrothermal activity of SiO₂-bearing fluids that originated from post-magmatic hydrothermal activity developed within host rocks and/or meteoric waters.

Agate nodules from Kerrouchen (Khénifra Province, Meknés-Tafilalet Region) in Morocco occur in Triassic basalts and reach up to 30 cm in diameter. Monocentric, banded agates—mainly in pastel pink, grey, white and yellow—with infiltration canals (osculum) are observed. Raman microspectroscopy revealed that the agates mainly consist of low quartz and subordinately moganite with distinctive 460 and 501 cm⁻¹ marker bands, respectively. Linear mapping indicated that moganite mainly concentrates in grey zones of the monocentric agate nodules. The other types, polycentric and pseudostalactitic agates, are usually brown and red and contain minerals such as hematite and goethite. They form both regular and irregular mosaics rich in ornamentation. Occasionally, aggregates of copper sulphides or titanium oxides (rutile) can also be observed. These minerals are sometimes accompanied by carbonaceous material marked by 1320 and 1585 cm⁻¹ Raman bands. It seems that formation of agates from Kerrouchen was induced by Si-rich and Fe-moderate fluids. Copper sulphides, rutile, and carbonates (possibly calcite) were most likely incorporated during post-magmatic processes. The origin of solid bitumen can be the result of hydrothermal or hypergenic processes.

This paper describes a newly discovered Bi-Cu±Au mineralization co-occurring with Pb-Zn-Ag hydrothermal mineralization within the Kizhnica-Hajvalia-Badovc ore field, central Kosovo, Vardar Zone. The mineralogy of two styles of Bi-Cu±Au mineralization was described using EPMA in combination with reflected and transmitted light microscopy. Hydrothermal Cu-Bi veinlets in the Kizhnica andesite quarry consist of Bi sulfosalts (bismuthinite, cosalite, aikinite, and krupkaite), pyrite, hematite, chalcopyrite, galena, sphalerite, and tetrahedrite group minerals. Disseminated Bi-Au-Cu-Te mineralization from the contact type of mineralization (hornfels) consists of Bi sulfosalts (cannizzarite, bismuthinite, galenobismutite, cosalite), associated with sulfarsenides (arsenopyrite, gersdorffite, and cobaltite), base metal sulfides (chalcopyrite, pyrite, sphalerite, pyrrhotite, and galena), native gold, native bismuth, and tetradymite. LA-ICP-MS analyses of sphalerite, chalcopyrite, and tetrahedrite indicate increased content of In and Sn in the Kizhnica Bi-Cu-Au mineralizing system, while LA-ICP-MS analyses in pyrites show the presence of many elements, e.g., Au, As, Co, Sb, Tl, Hg, Pb, Bi related to the structure of pyrite or controlled by nano-inclusions. The results suggest a connection between Bi-Cu±Au mineralization and the proximity to intrusive rocks, which may be helpful for Au exploration in Kosovo.

New mineralogical and mineral-chemical data from the Stan Terg deposit, Kosovo, revealed the presence of abundant Bi-sulphotellurides associated with Bi- and Sb-sulphosalts and galena in pyrite–pyrrhotite-rich skarn-free ore bodies (ores without skarn minerals). The Bi-bearing association comprises Bi-sulphotellurides (joséite-A, joséite-B, unnamed phase A with a chemical formula close to (Bi,Pb)₂(TeS)₂, unnamed phase B with a chemical composition close to (Bi,Pb)_2.5Te_1.5S_1.5), ikunolite, cosalite, Sb-lillianite, members of the kobellite series and Bi-jamesonite. Compositional trends of the Bi-sulphotellurides suggest lattice-scale incorporation of Bi–(Pb)-rich module and/or admixture with submicroscopic PbS layers in modulated structures, or complicated Bi–Te substitution. Cosalite is characterized by high Sb (max. 3.94 apfu), and low Cu and Ag (up to 0.72 apfu of Cu+Ag). Jamesonite from this mineralization has elevated Bi content, from 0.85 to 2.30 apfu. The negligible content of Au and Ag in the Bi-sulphotellurides, the low content of Ag in Bi-sulphosalts, together with the lack of Au–Ag bearing phases in the mineralization, indicate either ore deposition from fluid(s) depleted in precious metals, or physico-chemical conditions of ore formation preventing Au and Ag precipitation at the deposit site. The temperature of initial mineralization may have exceeded 400 °C as suggested by the lamellar exsolution textures observed in lillianite, which indicate breakdown textures from decomposition of high-temperature initial crystals. Non-stoichiometric phases among the Bi-sulphosalts and sulphotellurides studied at Stan Terg reflect modulated growth processes in a metasomatic environment.