A Combined EPMA and LA-ICP-MS Investigation on Bi-Cu-Au Mineralization from the Kizhnica Ore Field (Vardar Zone, Kosovo)

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 data on the reduced intrusion-related Au mineralization of Central Kolyma gold region: age, formation conditions, composition, orecontrolling factors

New data are presented on the formation conditions and ages of the reduced intrusion-related Au mineralization of the Vetrenskaya area in the Central Kolyma region. The mineralization is predominantly confined to intersections of Late Jurassic minor intrusive bodies and NE-trending fracture systems and is represented by zones of thin quartz veinlets with sericite-quartz halos. The major ore mineral is gold-bearing arsenopyrite (up to 10%), while minor minerals are represented by lellingite, pyrite, chalcopyrite, and pyrrhotite. Microscopic native gold of a low fineness is paragenetically associated with bismuth minerals (bismuthine, native bismuth, andtellurides of Bi and Au), forming microinclusions (1–10 μ) in the arsenopyrite. Isochronous Re-Os age of the goldbearing arsenopyrite is 137–117 Ma, which suggests the mineralization was formed significantly later than the hosting granitoids (147–153 Ma). The reduced intrusionrelated Au ore deposit was formed at shallower depths in comparison with orogenic Au deposits, and at lower temperatures in comparison with rare metal (W, Mo) ore deposits.

The Buenaventura Sector of the San Finx W–Sn Deposit (NW Spain): Ore Mineralogy, Host Rocks and Associated Hydrothermal Alteration

The San Finx W–Sn ore deposit is located in the Spanish province of A Coruña (Galicia, NW Spain). Geologically, it occurs in the Galicia-Trás-os-Montes zone which is one of the innermost zones of the Iberian Variscan collisional belt. This ore deposit is characterized by NE–SW trending quartz-dominated veins with centimeter-size hübnerite and cassiterite. This research focuses on one sector of this deposit known as Buenaventura. The aim of this work is to present a mineralogical and petrological characterization of the ore-bearing veins, their host rocks and associated hydrothermal alteration. The vein mineralogy is mainly quartz, muscovite, K-feldspar, apatite and scarce fluorite. The ore minerals are hübnerite, scheelite and cassiterite with columbite and ilmenorutile-struverite inclusions, together with sulfides, mainly chalcopyrite and arsenopyrite, and, in less abundance, molybdenite, löllingite, pyrrhotite, sphalerite, stannite, pyrite, Bi-Pb-Ag sulfosalts and native bismuth. The main host-rocks are micaschist and paragneiss and two types of pegmatites, homogeneous pegmatites and banded aplite-pegmatites with columbite. The host rocks are affected by four types of hydrothermal alterations: tourmalinization, greissenization, feldspathization and silicification. The more widespread alteration is the feldspathization in which the protolith is replaced by massive albite and K-feldspar with fibrous habit, accompanied by apatite, chlorite, rutile, magnetite, hematite, chalcopyrite and sphalerite. In addition, there are highly deformed areas with a complex alteration rich in K-feldspar and sulfides, mainly chalcopyrite, minerals of the stannite group and sphalerite and, in less abundance, bismuthinite, native bismuth, galena and pyrite. This deposit shares features in terms of geological setting, hydrothermal alteration and ore assemblages with exogreisen systems formed in the cupolas of highly fractionated granites in collisional settings.

Minerály kontaminovaných granitových pegmatitů z lomu Pohled u Havlíčkova Brodu (moldanubikum), část II: prvky a sulfidy

In the Pohled quarry near Havlíčkův Brod town (central part of Czech Republic), texturally and mineralogically simple contaminated anatectic pegmatites form dikes or irregular bodies cementing breccia of host metamorphic rocks (paragneisses, amphibolites) belonging to the Monotonous (Ostrong) Group of the Moldanubicum of the Bohemian Massif. They exhibit signs of intense hydrothermal overprint and also the presence of abundant disseminations, nests and veinlets of ore minerals. A detailed mineralogical study revealed the presence of an extraordinary rich ore assemblage (20 species in total, including one unnamed phase). The oldest minerals are sphalerite (rich in Fe), löllingite, Fe-Co-Ni sulphoarsenides (cobaltite, glaucodot, arsenopyrite, gersdorffite), pyrrhotite, galena and chalcopyrite, in later portion accompanied by inclusions of Bi-minerals (native bismuth, bismuthinite, joséite-A, joséite-B, ikunolite and a Pb-Bi sulphosalt). The composition of the Pb-Bi sulphosalt is equal to Ag,Fe-substituted eclarite; its identity was confirmed also by Raman spectrum. Pyrite is very abundant phase, present probably in several generations. The Fe-Co-Ni thiospinels disseminated in younger chlorite, and represented by siegenite, violarite, grimmite and an unnamed NiFe2S4 phase, are the youngest ore minerals. The mineral association as well as chemical composition of most ore minerals are well comparable to those of local polymetallic ore veins and Alpine-type veins, which give evidence for identical origin of all these ore mineralizations. The formation of pegmatite-hosted ore assemblage was long-lasting multiphase process, which took place at temperatures between ca. 350 and <120 °C during changing fugacities of sulphur, tellurium and oxygen. A distinct enrichment in cobalt and nickel of ore mineralization hosted by pegmatites (in comparison with hydrothermal veins) is explained in terms of pronounced interactions of fluids with amphibolites and serpentinites.

Pb-Bi mineralizace v amfibolitech z lomu Libodřice u Kolína (kutnohorské krystalinikum, Česká republika)

An interesting ore mineralization containing Pb-Bi minerals, present in a thin layer parallel with schistosity of the host amphibolite, was newly recognized in the Libodřice quarry near Kolín (Kutná Hora Crystalline Complex, Czech Republic). The disseminations of ore minerals are formed especially by pyrrhotite and chalcopyrite, less pyrite and accessory galena, native bismuth, cosalite, bismuthinite and joséite-B. The equilibrium textural relationships of rock-forming silicates and main sulphides indicate that the ore assemblage underwent metamorphic recrystallization together with the host rock, however, indications of younger local re-equilibrations under changed physico-chemical conditions (especially temperature, fugacity of sulphur, fugacity of oxygen) were also observed. The presence of polysynthetic lamellae in chalcopyrite suggests for its origin/re-crystallization at temperatures above 550 °C. Sporadic cosalite, stable at temperatures below 425 °C, was probably precursor of pseudomorphs today formed by galena and native bismuth. Pseudomorphs originated at temperatures below 271 °C probably due to local decrease of sulphur fugacity caused by growth of associated pyrrhotite. The local sulphurisation of small amount of native bismuth to bismuthinite and small part of pyrrhotite to pyrite finished the process of ore evolution. The presence of elevated contents of Te, Se and Ni in the studied mineralization confirms the source of these elements in the host rock environment, which was presupposed on the basis of earlier mineralogical study of Alpine-type veins in the area of the Kutná Hora Crystalline Complex.

New data on sulphosalts from hydrothermal siderite-type veins in the Spišsko-gemerské rudohorie Mts. (eastern Slovakia): 1. Nuffieldite and aikinite from Slovinky-Došťavná vein

A new occurrence of nuffieldite was recently discovered in a siderite-type hydrothermal vein with sulphides in Došťavná near Slovinky, Spišsko-gemerské rudohorie Mts., Spišská Nová Ves Co., Košice Region, Slovakia. It forms lead-gray acicular crystals reaching up to 1 cm in size or aggregates up to 2.5 cm, which are enclosed in quartz-siderite matrix together with chalcopyrite, pyrite, tourmaline and chlorite. Nuffieldite is frequently replaced by minor aikinite, galena and native bismuth. The refined unit-cell parameters of nuffieldite (for the orthorhombic space group Pbnm) are: a 14.5313(16) Å, b 21.454(2) Å, c 4.0500(6) Å and V 1262.58(19) Å3. The average (n=145 analyses) empirical formula of nuffieldite from Slovinky-Došťavná based on Pb+Bi+Sb = 5 apfu is corresponding to Cu1.30Pb2.00Bi2.00(Pb0.30Bi0.30 Sb0.40)1.00(S7.12Se0.03)7.15. Aikinite forms microscopic, anhedral to subhedral grains or aggregates replacing nuffieldite. The average (n=29) empirical formula of studied aikinite based on (Cu+Pb)/2+(Sb+Bi) = 8 apfu is Pb3.83Cu3.76(Bi4.12 Sb0.09)4.21(S12.40Se0.03)12.03.

New data on sulphosalts from the hydrothermal siderite-type veins in the Spišsko-gemerské rudohorie Mts. (eastern Slovakia): 2. Jaskólskiite and associated sulphosalts from the Aurélia II vein near Rožňava

New samples of jaskólskiite were recently collected at the Aurélia II siderite-type hydrothermal vein with sulphides near Rožňava, Spišsko-gemerské rudohorie Mts., Rožňava Co., Košice Region, Slovakia. It forms lead-gray, irregular aggregates up to 1.5 × 1 cm in size, which are enclosed in quartz-siderite gangue. Aggregates of jaskólskiite are consisting of individual, subhedral acicular crystals to 2 mm long, strongly replaced by younger bournonite and associated with Bi-rich jamesonite, tetrahedrite-(Fe), tintinaite, native bismuth and ullmannite. Significant variation of Cu (from 0.04 to 0.23 apfu) and Bi contents (from 0.32 to 0.77 apfu) was observed in studied sample. The average (n = 69 analyses) empirical formula of jaskólskiite from Rožňava-Aurélia vein based on Pb+Bi+Sb = 4 apfu is corresponding to Pb2.11Cu0.13(Sb1.42Bi0.47)1.89S5.14. Bi-rich jamesonite is the most common sulphosalt at the studied locality and it forms prismatic crystals up to 2 cm or irregular aggregates to 3 cm in size. The Bi content in jamesonite is ranging between 0.49 to 1.69 apfu. Bournonite is also common and two compositional types were distinguished. The first, dominant type is represented by Bi-rich bournonite (containing up to 0.14 apfu Bi). The second type of bournonite, represented by thin ribbons shows significant enrichment in As (reaching up to 0.49 apfu), but has only minor content of Bi (up to 0.08 apfu). Tintinaite is rare and its average (n = 9) empirical formula based on sum of all atoms = 63 apfu is corresponding to (Pb9.67Ag0.06)9.73(Cu2.55Fe0.40Zn0.07)3.02(Sb10.19Bi5.37)15.56S34.59Cl0.10.

Mineralogy of Skarn Ores from Băița-Bihor, Northern Apuseni Mountains, Romania: A Case Study of Cu-, Bi-, and Sn-minerals

The Antoniu, Antoniu North, and Blidar Contact orebodies from the Băița-Bihor skarn deposit, Romania have been investigated using optical and electron microscopy. Electron probe microanalyses were acquired on samples from the Blidar Contact orebody. Bornite is the most abundant Cu-sulfide and hosts native bismuth, joséite-B, emplectite, and wittichenite. Kësterite and ferrokësterite were identified for the first time in the Băița-Bihor deposit; the occurrence of stannite was also confirmed. Temperatures of ore deposition in the Blidar Contact orebody are constrained from the compositions of sphalerite-kësterite and sphalerite-ferrokësterite pairs at 287 ± 25 °C to 310 ± 35 °C, and 447 ± 17 °C to 503 ± 68 °C, respectively.

Platina in the 18th century: mineralogy of the crude concentrate used in the first modern attempts at refining platinum

A platina sample brought to Spain in the last quarter of the 18th century is nowadays exhibited at the National Museum of Natural Sciences in Madrid. It originated from the ancient Mineralogical Museum of the School of Applied Chemistry at El Turco Street in Madrid and most probably corresponds to the material used by François Chabaneau for his experiments to purify platinum metal in the late 18th century. The sample is a heavy-mineral concentrate consisting of Pt–Fe alloys and gold nuggets associated with ilmenite–hematite, chromian spinel, goethite and minor quartz, sphene, rutile, magnetite, hornblende, garnet, calcite, pyrite, native bismuth and bismite. The Pt–Fe alloys exhibit a characteristic composition (81.97–90.75 wt.% Pt and 5.08–10.81 wt.% Fe with minor amounts of Cu, Os, Ir, Ru, Rh and Pd) and mineralogy of solid inclusions (abundant inclusions of Ir alloy as well as Os alloy, laurite–erlichmanite, bowieite, tulameenite and undetermined Pt–Pd–Ir–Rh antimonides and tellurides) that are very similar to those Pt–Fe alloys currently mined in western Colombia (the Chocó Department). These features allow us to discuss the provenance of the sample (probably from the proximal or medial reaches of any of the Chocó rivers) and evaluate the suitability of the Chabaneau's method for purifying platina. Our results show that the method became effective only with platina samples depleted or lacking iridium.

Neobvyklá žilná Cu-Zn-Ag-Pb-As-Sb-Se-Sn-Bi mineralizace z Jedové jámy u Vejprt v Krušných horách (Česká republika)

An extraordinary rich mineral assemblage consisting of 27 minerals has been newly discovered in quartz veins of the abandoned ore deposit, once exploited by the Drei König Mine, called also Giftschacht (Jedová jáma - Toxic shaft), situated approximately 2 km SE of Vejprty town. It includes 16 sulphides (plus one unnamed) with far prevailing arsenopyrite. In addition to common sulphides (chalcopyrite, sphalerite, galena and minerals of the tetrahedrite group), a wide suite of sulphosalts with substantial Bi-content was identified. Besides common bismuthinite and emplectite, also relatively rare Bi minerals (matildite, aikinite, hammarite, wittichenite), in the Czech Republic known from few localities only, have been found here. Bi is bound also in a rather exotic selenide bohdanowitzite and native bismuth. Bi is substantially present in some domains of tetrahedrites [tetrahedrite-(Zn), tennantite-(Zn) and tennantite-(Fe)]. In addition to local Bi enrichment, also Sn-minerals occur in the ore, represented by cassiterite and rare sulphides (kësterite and stannoidite). The presence of phosphates of the plumbogummite group [plumbogummite, goyazite and florencite-(Ce)] contributes to the remarkable mineral assemblage. From geochemical point of view, very interesting is the presence of florencite-(Ce), in which REE with dominating Ce are fixed. In addition, grains of fluorite, fluorapatite, rutile, topaz and aggregates of illite and a phase from kaolinite group are present. Supergene mineralization is represented besides limonite by abundant scorodite and rare strengite.