Native Bismuth Research Articles

The origin of the Avram Iancu U–Ni–Co–Bi–As mineralization, Băiţa (Bihor) metallogenic district, Bihor Mts., Romania

The Băiţa metallogenic district in the Bihor Mountains is a historically important mining area in Romania. Uranium mining took place between 1952 and 1998 from various deposits, but very little is known about the geology and mineralogy of these deposits. In this paper, we describe geology and mineralogy of uranium mineralization of the Avram Iancu uranium mine from waste dump samples collected before complete remediation of the site. Texturally and mineralogically complex assemblages of nickeline, cobaltite–gersdorffite solid solution, native Bi, Bi-sulfosalts, molybdenite, and pyrite–chalcopyrite–sphalerite occur with uraninite, “pitchblende,” and brannerite in most of the ore samples. The association of nickel, cobalt, and arsenic with uranium is reminiscent of five-element association of vein type U–Ni–Co–Bi–As deposits; however, the Avram Iancu ores appear to be more replacement-type stratiform/stratabound. Avram Iancu ore samples contain multistage complex, skarn, uranium sulfide, arsenide assemblages that can be interpreted to have been formed in the retrograde cooling stages of the skarn hydrothermal system. This mineralizing system may have built-up along Upper Cretaceous–Paleogene “Banatite” intrusions of diorite-to-granite composition. The intrusions crosscut the underlying uraniferous Permian formations in the stacked NW-verging Biharia Nappe System. The mineralization forms stacked, multilayer replacement horizons, along carbonate-rich lithologies within the metavolcanic (tuffaceous) Muncel Series. Mineral paragenesis and some mineral chemistry suggest moderate-to-high <450, i.e., 350–310 °C, formation temperatures for the uranium sulfide stage along stratigraphically controlled replacement zones and minor veins. Uranium minerals formed abundantly in this early stage and include botryoidal, sooty and euhedral uraninite, brannerite, and coffinite. Later and/or lower-temperature mineral assemblages include heterogeneous, complexly zoned arsenide–sulfarsenide solid solutions associated with minute but abundant uranium minerals. Within the later arsenide–sulfarsenide mineral assemblage, there is great variation in Ni, Co, and S content with generally increasing arsenic content. Uranium minerals in this late-stage assemblage include very fine euhedral uraninite and brannerite inclusions in arsenide–sulfarsenide minerals. Native bismuth and Bi-sulfosalt krupkaite are observed in this As–S-rich assemblage strongly associated with cobaltite.

As–Sb–Bi–Au mineralization in the Baogutu gold deposit, Xinjiang, NW China

Here we report the occurrence of some uncommon mineral assemblages including pääkönenite, aurostibite, native arsenic, native antimony, and native bismuth found in the Baogutu gold deposit in the western Junggar, Xinjiang, NW China. The mineralization could be generally subdivided into two types: the gold-bearing quartz-vein type mineralization and disseminated mineralization in the wall rocks. The sulfide minerals in gold lodes commonly include pyrite, arsenopyrite, marcasite, and stibnite. However, the L7 lode in No. 4 orebody and the L1 lode in No. 11 orebody of the Baogutu gold deposit are quite different in terms of their mineral assemblages. The L7 lode contains native arsenic–quartz veins in shallow levels and stibnite–quartz veins at depth. Gold-bearing minerals (electrum, native gold, and rarely aurostibite) mainly coexist with pääkönenite, stibnite, native arsenic, and native antimony. The crystallization of As- and Sb-bearing minerals was likely to have consumed H2S from the hydrothermal fluid, which probably triggered the precipitation of native gold. The L1 lode consists of several discontinuous sulfide-dominated lensoid orebodies. The massive sulfide ores that produced most of the gold resource are characterized by an intimate association between native bismuth and native gold mineralization.

First native silica findings in bismuth from garnet skarns of Ribny Log - 2 gold ore target in Topolninsk ore deposit (Gorny Altai)

The nanomineralogic investigation results of ore minerals in metasomatites (garnet skarns) of Ribny Log- 2 gold ore in Topolninsk ore deposit (Gorny Altai) revealed the native silica impurities (Si) of 1 - 5 nm within the grains of native bismuth (Bi). Polished sections were examined by using Tescan Vega 3 scanning electron microscope (SEM) with Oxford energy-dispersive spectrometer at the Department of Geology and Mineral Exploration, Institute of Natural Resources, Tomsk Polytechnic University.

Structural, mineralogical and geochemical constraints on the atypical komatiite-hosted Turret deposit in the Agnew–Mt. White district, Western Australia

In the Norseman–Wiluna belt, Yilgarn Craton, the Agnew–Mt. White district is the host of many gold deposits. Located in the hinge of the regional Lawlers anticline, the Turret gold deposit is structurally controlled by the Table Hill shear zone that transects the Agnew Ultramafic unit. Geochemistry, coupled with petrographic data, allowed the delineation of the paragenetic sequence associated with gold mineralisation and include (1) a pervasive talc-carbonate alteration assemblage, (2) a pre-mineralisation stage associated with pervasive arsenopyrite + chalcopyrite + pyrrhotite + pyrite alteration, followed by (3) a late deformation event along a dilatational segment of the main Table Hill shear zone, leading to the formation of a breccia hosting a Cu–Bi–Mo–Au (± Ag ± Zn ± Te ± W) metal assemblage. The presence of Au–Ag–Cu alloys, native bismuth, chalcopyrite and other Bi–Te–S phases in the mineralisation stage suggest that gold may have been scavenged from the hydrothermal fluids by composite Bi–Te–Cu–Au–Ag–S liquids or melts. Using this mineral paragenetic sequence, together with mineralogical re-equilibration textures observed, we show that the gold deposition at Turret occurred over a temperature range approximately between c. 350 and 270 °C. This temperature range, together with the structural control and typical mesothermal alteration pattern including carbonate–chlorite alteration, shows that the Turret deposit shares common characteristics with the orogenic gold deposit class. However, the metal association of Cu, Au, Bi, and Mo, the quartz-poor, and high copper-sulphide content (up to 15 %) are characteristics that depart from the typical orogenic gold deposit mineralogy. Through comparison with similar deposits in the Yilgarn Craton and worldwide, we propose that the Turret deposit represents an example of a porphyry-derived Au–Cu–Bi–Mo deposit.

Cu–Au vein mineralization related to the Talat n’Imjjad shear zone (western High Atlas, Morocco): geological setting, ore mineralogy, and geochemical evolution

The Cu–Au deposit of the Talat n’Imjjad occurrence, southwestern Azegour mine, western High Atlas of Morocco, is situated in a NW trending quartz vein along a shear zone in quartz diorite host rocks. The recently discovered shear zone, ~200-m long, NW–SE trending, so-called Talat n’Imjjad vein system of Cu–Au–Bi–Te–Se mineralization that crosscuts the Al Medinet quartz diorite, represents a landmark in regional metallogeny. This region has long been known for its polymetallic ore deposits, with the historical Mo–Cu–W mine of Azegour and Pb–Zn–Ag mine of Erdouz. The economic sulfide enrichment is often hosted by breccias and quartz veins in the ductile shear zone. Samples from the field surface and boreholes show macro- and microscopic evidence of shearing such as S-C fabrics and microshear planes. The quartz diorite was deformed and mylonitized, then the igneous texture was modified. On the basis of textures, mineral assemblages, and hydrothermal alteration, four stages were documented and could be distinguished: (1) quartz I–sericite–chlorite–epidote pre-ore stage; (2) chlorite–quartz II–calcite–pyrite ore stage; (3) native bismuth–bismuthinite–emplectite–wittichenite–(tsumoite–laitakarite)–chalcopyrite–sphalerite–native gold–calcite ore stage II; and (4) bismuthite–hematite–malachite–covellite post-ore stage. Bi-chalcogenides are considered as pathfinders for gold in Au–quartz veins. The association of gold with Bi-minerals is linked to the role of Bimelt as scavenger for gold. Tellurides and selenides are also the best indicators of the magmatic signature. The alteration types of the wall rocks include seritization, silicification, chloritization, carbonatization, and propylitization. The auriferous shear zone of Talat n’Imjjad represents a newly discovered occurrence in the western High Atlas characterized by its mineralogy, paragenetic sequence, hydrothermal alteration, and magmatic and structural control of the deposit of sulfide minerals.

The Occurrence of Tellurium and Bismuth in the Gold-Bearing Polymetallic Sulfide Ores in the Sudetes (Sw Poland)

Streszczenie W artykule szczegółowo scharakteryzowano pod względem mineralogicznym i geochemicznym występowanie telluru i bizmutu w złotonośnych siarczkowych rudach polimctalicznych z zarzu- conych złóż (Złoty Stok, Czarnów, Radzimowicc i Radomicc) oraz punktu mineralizacji (Bardo Śląskie) w Sudetach. Tellur jest zaliczany do pierwiastków krytycznych, a jego rola stale wzrasta. Na rynkach światowych popyt na tellur znacznie przewyższa jego podaż zc względu na coraz większe wykorzystanie np. w produkcji paneli słonecznych czy nośników informacji. Maksymalne kon- centracje telluru około 150 ppm stwierdzono w rudach arscnopirytowo-chalkopirytowych w Ra- dzimowicach, a najwyższe koncentracje bizmutu (ok. 0,5%) w rudach siarczkowych w Czarnowie. W pozostałych obszarach koncentracje Tc są na poziomic od kilku do kilkudziesięciu ppm, a w przy- padku Bi od kilkudziesięciu do kilkuset ppm. Zawartości tc znacznie przewyższają klarki tych metali w skorupie ziemskiej. Wśród zidentyfikowanych minerałów telluru w Radzimowicach i Czarnowie dominują tcllurki Ag (hessyt) oraz w Bardzie Śląskim tcllurki Bi (hcdlcyit i tcllurobismutyt). Tcllurki występują głównie w postaci mikro-wrostków w minerałach siarczkowych w paragcnczic z mi- nerałami Au, Ag i Bi. Minerały bizmutu rozpoznano we wszystkich zbadanych miejscach i re- prezentowane są głównie przez bizmut rodzimy i wtórny minerał bizmutu -bismutynit. Tellur i bizmut wykazują przeważnie silną korelacje (cc&gt;0,6) z Au, Ag i Pb. Krystalizacja głównych minerałów Bi i Tc nastąpiła w zakresie temperatur średnich (300 to 200°C) w dwóch etapach. Pierwszy związany głównie z krystalizacją tcllurków Bi w strefach kontaktowo-mctasomatycznych wokół waryscyjskich intmzji granitoidowych (Czarnów i Bardo Śląskie) i drugi - związany z krystalizacją tcllurków Ag w procesach cpitcrmalnych wokół intruzji porfirowych (Radzimowicc). Bi i Tc odgrywały donośną rolę w procesie wytrącania złota z roztworów hydrotcrmalnych. Pierwiastki tc mają znaczenie mctalogcnicznc i wskaźnikowe przy poszukiwaniach złota.

Gold mineralization in the Ourika Gneiss (High Atlas of Marrakech, Morocco): mineral paragenesis and fluid P-T-X evolution

The Ourika gold showing lies in the High Atlas of Morocco, near Marrakech. It is mainly hosted by Precambrian gneiss and basic dykes, and is controlled by shear zones. Gold mineralization occurs mainly within quartz structures. Fracturing and mineralization are interpreted to have occurred in three stages. Early and intermediate stages involved the deposition of an arsenopyrite–pyrite–quartz–chlorite assemblage, and a chalcopyrite–arsenopyrite–pyrite–quartz–chlorite assemblage, respectively. Early intermediate stage fluid inclusions belong to the C-H-O-N system typical of the retrograde metamorphism that affects the Pan-African terranes at P-T conditions of 140–300 MPa and 240–450 °C, and moderate ductile–brittle deformation. Deposition of native gold, bismuth, bismuthinite and galena during the ore stage from low-salinity aqueous fluids was related to downward penetration of meteoric waters, trapped at P-T conditions of 20–110 MPa and 170–210 °C. Evolving physical conditions and fluid compositions from early to late fluid stages played important roles in ore-forming processes. Owing to structural observations, ore-forming fluids could be linked to regional Variscan hydrothermal event. Gold crystallised as native particles in microfissures crosscutting earlier sulphides. Thus, the gold deposition was late, and appears as a consequence of deeply penetration of oxidising fluids favoured by microfracturing of the already ore (As–Fe–Cu) structures.

Gold-bismuth-telluride mineralization in ores from the Serebryanoe deposit of the Lugokan ore cluster of Eastern Transbaikalia

The Au-Bi-Te mineralization is found and studied at the Serebryanoe deposit in Eastern Transbaikalia. The microprobe analyses of the native gold and sulfides and the sulfur isotopic composition of the sulfides are presented. The early gold-pyrite-arsenopyrite and late gold-polymetallic assemblages with sulfides, sulfotellurides and tellurides of Bi, native bismuth and gold, and Au-Bi intermetallide were distinguished. It is concluded that the Au-Bi-Te mineralization is genetically related to the porphyry monzonites of the Shakhtama complex on the basis of their 40Ar/39Ar age.

Genetically related Mo–Bi–Ag and U–F mineralization in A-type granite, Gabal Gattar, Eastern Desert, Egypt

Molybdenum–bismuth–silver and uranium–fluorine mineralization in the Gabal Gattar area are genetically related. Both are hosted in fractionated and hydrothermally altered A-type granite. While Mo–Bi–Ag ore is hosted in NS striking quartz veins, the U–F mineralization forms batches and micro-veinlets, controlled by NNE to NW trending structures. U was incorporated in late-magmatic hypogene minerals (e.g. zircon and xenotime) and in U–Th-minerals closely associated with fluorite. Molybdenite, native bismuth, galena, chalcopyrite, sphalerite, aikinite “PbCuBiS3”, berryite “S16(Cu,Ag)6 Bi7Pb3” and native silver were identified in the quartz veins. Fluid inclusions occur in fluorite (Type-1) associated with U minerals and in quartz (Type-2) from Mo-bearing veins. Type-1 and 2 inclusions homogenize at temperatures between 220°C and 106°C, their salinity ranges from 1.3 to 10wt.% NaCleq, respectively. F-rich fluids accumulated at the last stage of granite crystallization, extracted ore metals and deposited them in a shallow hydrothermal system. Mo, Bi and Ag precipitated earlier from saline fluids due to cooling, fluid mixing and wallrock sulfidation. U–F minerals precipitated from low-salinity fluids after high input of meteoric water.

Petrogenesis of bismuth minerals in the Dabaoshan Pb–Zn polymetallic massive sulfide deposit, northern Guangdong Province, China

Located in the northern Guangdong Province, the Dabaoshan Pb–Zn polymetallic massive sulfide deposit is one of the most important regions to have produced Fe, Cu, Pb, Zn and S in southern China. While much progress has been made with respect to the geology and geochemistry of the deposit, a better understanding of ore genesis is warranted. This ore body contains abundant bismuth element, only few studies exist on the distribution characteristics and existing states of bismuth. Electron microprobe study yields that native bismuth, tellurides (e.g. hedleyite) and sulfide minerals, are the main forms in which this element is found. The occurrence and characteristics of native bismuth and its mineral assemblages are different with high-T gold-bearing deposits, but are more similar to those of mid-low temperature hydrothermal deposits. Our research shows that the Bi(Te) at Dabaoshan derived from the Late Yanshanian dacite porphyry. The Bi(Te)-rich ore-forming fluid developed during intrusion of the dacite and mineralized along fractures, and overprint the earlier Pb–Zn mineralization. During the early overprinting event, the ore-forming fluid was rich in Bi and Te and poor in S, under uniform mid-temperature conditions. As the hydrothermal fluids evolved, they became enriched with Ag and Pb. Sulfur was rich in the fluid during the late overprinting event; this may have been related to dissolution of sulfide. The low abundances of Bi, Te and Ag in sulfide minerals (e.g., galena and sphalerite), indicate that ore genesis and the ore-forming materials were different between the Pb–Zn and Bi–Te–Ag stages. Thus, new geological and geochemical data were used to delineate the sequence ore genesis of Dabaoshan Pb–Zn mineralization.

The Mokrsko-West gold deposit, Bohemian Massif, Czech Republic: Mineralogy, deposit setting and classification

The Mokrsko-West deposit is unique among European Variscan gold deposits from the points of view of both the structure (an approx. 200m thick complex of sheeted, several mm-thick, densely spaced quartz veins) and the economic viability (gold reserves of about 100t). The deposit is hosted mainly by tonalite of the calc-alkaline Sázava tonalite suite (ca. 354Ma) of the Central Bohemian Plutonic Complex. Mineralization is characterized by quartz-dominated gangue, no visible hydrothermal alteration, low sulfide content, high fineness native gold accompanied by maldonite, aurostibite, native bismuth and numerous Bi–Te–(S) phases. Five mineralogical stages are described in great detail. Arsenopyrite and chlorite thermometers, mineral phase stabilities and published isotope and fluid inclusion data are used to reconstruct the temperature and compositional evolution of the system. The role of liquid bismuth in the sequestration of gold is also discussed.The deposit shares the features of both orogenic gold (ORG) and intrusion-related gold (IRG) deposits. The IRG model is advocated by close spatial association between the ore zone and the tonalite host-intrusion, by the absence/scarcity of hydrothermal alteration, by the Au–Bi–Te–As elemental association and by marked thermal gradients from the early to late mineralization stages. The ORG model is advocated by an approx. 15–10Ma gap between the intrusion of the tonalite-host and the ore formation, by isotope and geochemical evidence for a key role of metamorphic fluids in the mobilization and transfer of many elements/species (inclusive S and Au). The apparently ambiguous classification of the deposit can most probably be attributed to deposit formation at a depth of ≥9km and to setting of the deposit at/inside a large-scale plutonic complex with multiple and prolonged tectonic and intrusive activity.

Geochemistry and behavior of REE in stream sediments close to an old Sn-W mine, Ribeira, Northeast Portugal

The abandoned Sn-W Ribeira mine, northeast of Portugal, contained quartz veins with cassiterite, wolframite, scheelite, pyrite, arsenopyrite, sphalerite, chalcopyrite, manganocolumbite, bismuthinite, native bismuth, phosphates and carbonates. The exploration took place on the northern slope of the Viveiros stream, which is an affluent of the Sabor River. The waste-rock dumps and tailings were deposited on the hillside, close to the mine and are nowadays exposed to significant weathering and erosion, as they are not vegetated. The eroded material is transported by the Viveiros stream toward the Sabor River. A seasonal stream drains the tailings. The stream sediments samples were collected along the Viveiros stream, in the seasonal stream, in a seasonal spring at the bottom of the tailings, in the Sabor River and in other streams not affected by mine workings, following the mine influence along the Viveiros stream and in the Sabor River (1.2km away from the mine workings). The data show that the degree of pollution increases along the Viveiros stream, especially in winter. The highest degree of pollution is for As, In, W, Sn and Bi. The sediments from the drainage of the main tailings are particularly polluted during winter, by Bi, In and Sn. The sedimentary precipitate from the spring is polluted in Cu, As, In, Sn, Ta, W, Bi, Zn, Nb, Ag, Sb and Ta. The sediments from the Sabor River are significantly polluted by As, Ag, In, Sn, W and Bi. The sediments from the regional streams, Viveiros stream and Sabor River have similar REE (NASC normalized) patterns (ΣREE=131.7–185.9mg/kg, LaN/LuN=1.23–1.42 and Eu/Eu*=1.02), while those from the seasonal stream, crossing the main tailings, are enriched in REE (ΣREE=250.3–283.6mg/kg, LaN/LuN=1.6–2.09 and Eu/Eu*=0.96). The general decrease in LaN/LuN values with increase in total Fe2O3 can be explained by the partitioning of HREE to the solid Fe-oxides phase. The sedimentary precipitate and coatings, which are mainly formed by Fe-oxy-hydroxides, but also contain jarosite, are impoverished in all REE. The impoverishment can be explained by the release of REE from the surface of the Fe-oxy-hydroxides, which occurs due to a local lowering of pH, caused by jarosite dissolution. During successive alternate cycles of wet and dry conditions, takes place the formation of Fe-oxy-hydroxides and jarosite in the sedimentary precipitate and coatings. The subsequent dissolution of jarosite releases acidity, thus promoting de-sorption of REE from the Fe-oxy-hydroxides mineral phases.

SEM studies of ore minerals in skarns from Garby Izerskie, Karkonosze-Izera block, south-western Poland

Abstract In “Stanisław” quarry, that is located on Garby Izerskie, ore minerals-bearing calcsilicate skarns were found in 2009. The samples were studied using microscopical method of reflected light and scanning electron microscopy (SEM). Based on SEM study, the predominant ore minerals in investigated samples are chalcopyrite, pyrrhotite, bismuth telluride and native bismuth. Moreover, acanthite, native gold and native silver were also identified. Our studies are the first report of above mentioned minerals from the Garby Izerskie area.

Gold deposit in the Butarny granitoid stock, Russian Northeast

The Butarny gold deposit is situated in the central part of the Khurchan-Orotukan Zone of tectonomagmatic activation, which is traced for 150 km in the near-meridional direction, and localized in the slightly eroded Late Jurassic granitoid stock of the same name. The explored orebodies are quartz veins and pinnate veinlets with low-grade pocket-disseminated sulfide (mainly arsenopyrite) mineralization containing native gold. The Bi-bearing gold-pyrite-arsenopyrite and the quartz-lollingite-arsenopyrite-stibnitejamesonite stages of the veined low-sulfide ore formation have been distinguished. The main mineral assemblage consists of arsenopyrite, native gold, and native bismuth. The minerals-carriers of gold were deposited during the final stage of ore-bearing quartz crystallization at 334−245°C from low-concentrated pneumatolytic-hydrothermal carbonated fluid containing CO2 and CH4 (5.8−2.2 and 1.6−0.5 mol/kg of solution, respectively). The ore-bearing fluid had variable salinity (5.3−2.2 wt % NaCl equiv). It is quite probable that the gas-saturated fluid participated in transport and precipitation of ore matter. Its density varies from 1.02 to 0.77 g/cm3. The pressure is estimated at 1600 to 780 bar. The fluid regime of ore formation at the Butarny deposit is similar to that of typical intrusion-related gold deposits. The Au tenor of beresitized granodiorite, numerous quartz veinlets, and extensive Au-bearing weathering mantle allow us to suggest stockwork mineralization.

대현 금-은광상의 모암변질에 따른 원소분산

대현 금-은광상은 Cambro-Ordovician 석회암질 대리암내에 발달된 NE 방향성의 단열대를 따라 형성된 2개의 열수성 석영맥으로 구성된다. 모암변질시 원소 분산과 이득/손실을 알아보기 위해 모암, 열수변질대 및 금-은 광맥에서 시료를 채취하였다. 모암변질시 뚜렷한 변질대가 관찰되지 않으며 구성광물은 주로 방해석, 돌로마이트, 석영과 소량 녹염석 등이다. 이 광상의 광석광물은 유비철석, 자류철석, 황철석, 섬아연석, 황석석, 황동석, 방연석, 에렉트럼, 자연 창연 및 은 광물 등이 산출된다. 분석된 자료를 기초로, 모암은 주로 <TEX>$SiO_2$</TEX>, CaO 및 <TEX>$CO_2$</TEX>로 구성되며 소량 <TEX>$Al_2O_3$</TEX>, <TEX>$Fe_2O_3(T)$</TEX> 및 MgO 등이 함유되어 있다. 광체로부터 모암으로 감에 따라 <TEX>$SiO_2$</TEX>, <TEX>$Fe_2O_3(T)$</TEX>, MgO, CaO 및 <TEX>$CO_2$</TEX> 함량은 변화 폭이 크게 관찰된다. 모암변질시 모암의 물리-화학적 물성 때문에 원소 분산은 현저히 관찰되지 않으며 단지 광체 주변부에서만 관찰된다. 모암변질시 이득원소들은 <TEX>$Fe_2O_3(T)$</TEX>, 총 S, Ag, As, Bi, Cd, Cu, Ni, Pb, Sb, Sn, W 및 Zn이고 손실원소들은 <TEX>$SiO_2$</TEX>, MnO, MgO, CaO. <TEX>$CO_2$</TEX> 및 Sr 이다. 따라서 우리의 결과물은 황강리 광화대내 석회암질 대리암을 모암으로 갖는 광상들의 지화학탐사시 활용될 수 있을 것이다. The Daehyun gold-silver deposit consists of two hydrothermal quartz veins that fill NE-trending fractures in the Cambro-Ordovician calcitic marble. I have sampled wallrock, hydrothermaly-altered rock and gold-silver ore vein to study the element dispersion and element gain/loss during wallrock alteration. The hydrothermal alteration doesn't remarkably recognized at this deposit and consists of mainly calcite, dolomite, quartz and minor epidote. The ore minerals composed of arsenopyrite, pyrrhotite, pyrite, sphalerite, stannite, chalcopyrite, galena, electrum, native bismuth and silver-bearing mineral. Based on analyzed data, the chemical composition of wallrock consists of mainly <TEX>$SiO_2$</TEX>, CaO, <TEX>$CO_2$</TEX> with amounts of <TEX>$Al_2O_3$</TEX>, <TEX>$Fe_2O_3(T)$</TEX> and MgO. The contents of <TEX>$SiO_2$</TEX>, <TEX>$Fe_2O_3(T)$</TEX>, MgO, CaO and <TEX>$CO_2$</TEX> vary significantly with distance from ore vein. The element dispersion doesn't remarkably recognized during wallrock alteration and only occurs near the ore vein margin because of physical and chemical properties of wallrock. Remarkable gain elements during wallrock alteration are <TEX>$Fe_2O_3(T)$</TEX>, total S, Ag, As, Bi, Cd, Cu, Ni, Pb, Sb, Sn, W and Zn. Remarkable loss elements are <TEX>$SiO_2$</TEX>, MnO, MgO, CaO. <TEX>$CO_2$</TEX> and Sr. Therefore, Our result may be used when geochemical exploration carry out at deposits hosted calcitic marble in the Hwanggangri metallogenic district.

Bismuthinite derivatives, lillianite homologues, and bismuth sulfotellurides as indicators of gold mineralization in the Stanos shear-zone related deposit, Chalkidiki, northern Greece

Arsenic-copper-gold-bismuth mineralization in the Stanos area is hosted by a km-long, NW-SE trending ductile to brittle shear zone within Silurian orthogneisses of the Vertiskos terrane of the Servomacedonian Massif, Chalkidiki Peninsula, northern Greece. Shearing was accompanied by iron-potassic alteration of the gneisses including biotite, muscovite, chlorite, apatite, zircon, quartz, and minor rare-earth element phosphates. Metallic minerals form disseminated to massive aggregates along foliation planes, asymmetric crenulation cleavages, and S-C9 fabrics. Detailed textural investigation of the ore assemblages revealed two stages of hydrothermal mineralization during shearing. An initial introduction of iron sulfdes (pyrite, arsenopyrite, and pyrrhotite) was followed by a copper-bearing stage that is associated with the formation of chalcopyrite, minor sulfdes (galena, sphalerite, and molybdenite), and Bi-Cu-Pb-Au-Ag-Te minerals. The stage II metallic mineral association consists mainly of Bi sulfosalts (bismuthinite derivatives, lillianite homologues, matildite), native elements (bismuth, electrum), and bismuth chalcogenides (joseite-A, joseite-B, ikunolite, and unnamed Bi-Pb-bearing sulfotellurides). The bismuthinite derivatives are mainly bismuthinite (including cuprian varieties), gladite-krupkaite, paarite, salzburgite, and an unnamed CuPbBi 7 S 12 phase. The ikunolite is Se-free, corresponding to the formula Bi 4 S 3 , and is the first known occurrence in Greece. Most stage II minerals exist in two-, three-, and, more rarely, four-component blebs or patches generally with curvilinear boundaries, suggesting the possibility that they were precipitated in a molten form. Phase relationships among minerals in the system Au-Bi-Te-Pb-Ag-Cu indicate that they formed by successive hydrothermal pulses from fluids that penetrated the shear zone at different times contemporaneous with ductile deformation. These pulses deposited the following assemblages in paragenetic order: molybdenite + cosalite + native bismuth + galenobismutite → gustavite/lillianite + native gold + native bismuth + bismuth sulfotellurides → bismuthinite-aikinite solid solution series→ matildite + native bismuth + galena → chalcopyrite + bornite. The observed association suggests that the system evolved under fluctuating f (S 2 ) and f (O 2 ) conditions and precious metals may have been scavenged by composite Bi-Te-Pb-S melts at temperatures well above 350 oC. The enrichment of Bi, Mo, Pb likely indicates a magmatic contribution to the ore-forming fluid.

Polymetallic mineralization in Ediacaran sediments in the Żarki-Kotowice area, Poland

AbstractIn one small mineral vein in core from borehole 144-Ż in the Żarki-Kotowice area, almost all of the ore minerals known from related deposits in the vicinity occur. Some of the minerals in the vein described in this paper, namely, nickeline, hessite, native silver and minerals of the cobaltite-gersdorffite group, have not previously been reported from elsewhere in the Kraków-Lubliniec tectonic zone. The identified minerals are chalcopyrite, pyrite, marcasite, sphalerite, Co-rich pyrite, tennantite, tetrahedrite, bornite, galena, magnetite, hematite, cassiterite, pyrrhotite, wolframite (ferberite), scheelite, molybdenite, nickeline, minerals of the cobaltitegersdorffite group, carrollite, hessite and native silver. Moreover, native bismuth, bismuthinite, a Cu- and Ag-rich sulfosalt of Bi (cuprobismutite) and Ni-rich pyrite also occur in the vein. We suggest that, the ore mineralization from the borehole probably reflects post-magmatic hydrothermal activity related to an unseen granitic intrusion located under the Mesozoic sediments in the Żarki-Pilica area.

Unusual mineralization with niobian titanite and Bi-tellurides in scheelite skarn from Kamenné doly quarry near Písek, Moldanubian Zone, Bohemian Massif

*� Correspondingauthor Clinopyroxene-garnet scheelite skarn containing accessory niobian titanite, native bismuth and Bi-tellurides of the Bi 2 X and Bi 5 X 3 series, together with Fe- and Fe-As sulphides, is associated with the contact of chondrodite marble with melanocratic granite-quartz syenite (durbachite). Hedenbergite-rich vein in this marble can be considered as an additional type of skarn. The presence of accessory niobian titanite is typical, in particular, of the veins. In addition to increased Nb contents (≤ 10.6 wt. % Nb 2 O 5 ; ≤ 0.164 apfu Nb) and locally Ta (≤ 4.07 Ta 2 O 5 ; ≤ 0.038 apfu Ta), it is relatively rich in Al (≤ 0.253 apfu). Locally it contains elevated Fe, Sn, Zr and F contents. Negative correlations of Al + F with R 4+ and Al + (Nb 5+ , Ta 5+ ) with R 4+ accompanied by low contents of Na in titanite correspond to the substi- tutions Al(OH,F)(TiO) -1 and Al(Nb,Ta)Ti -2 . Niobian titanite has anomalous composition if compared to skarn mineral assemblages worldwide. The Bi-(sulpho-) telluride with empiric formula Bi 1.98 (Te 0.66 S 0.34 Se 0.02 ) Σ1.02 is a member of the Bi 2 X series, whose members were described from numerous localities as unnamed minerals. In contrast to the publis- hed data this phase contains increased sulphur contents up to 0.33 apfu. The second Bi-(sulpho-) telluride with empiric formula (Bi 4.51 Fe 0.40 Cd 0.03 Pb 0.02 Sb 0.01 As 0.01 ) Σ4.98 (Te 1.58 S 1.36 Se 0.08 ) Σ3.02 is probably a S-rich member of the Bi 5 X 3 series. In the evolution of the skarn it is possible to distinguish stage I responsible for the formation of the older Mg- and younger Ca-skarns, and stage II, characterised by increased Fe contents. The scheelite-sulphide mineralization was formed during a third (retrogression) stage followed by brittle deformation. Emplacement of siderite ± quartz veins represents the fourth (terminal) stage of mineralization.

Insights into the Liquid Bismuth Collector Model Through Analysis of the Bi-Au Stormont Skarn Prospect, Northwest Tasmania

The liquid bismuth collector model has previously been proposed to explain the common association between gold and bismuth seen in many ore deposits, and involves the scavenging of gold from hydrothermal fluid by liquid bismuth. Here, textural relationships and temperature and chemical conditions of mineralization at the Stormont Bi-Au skarn prospect in northwestern Tasmania are analyzed to investigate whether the liquid bismuth collector model can explain gold accumulation at this prospect. The calc-silicate skarn assemblage containing grandite, hedenbergite, actinolite, magnetite, epidote, quartz, and calcite suggests that initial metasomatism involved temperatures >400° to 500°C. Visible gold is associated with native bismuth, bismuthinite, maldonite, galena, and an unknown Bi-Te-S mineral. Native bismuth is directly associated with grandite, which formed during initial stages of metasomatism. This implies that bismuth would have precipitated from a hydrothermal fluid as a liquid. Heating experiments showed that bismuth alloy inclusions in garnet melt between temperatures of 250° and 288°C. The mineralization setting at Stormont and textural relationships suggest that gold was scavenged from hydrothermal fluids by liquid bismuth. Rhythmically zoned grandite crystals provide evidence for fluctuating hydrothermal fluid conditions, which may have contributed to dissolution and reprecipitation of gold, thus facilitating an ore zone refining process within the prospect. This refining process is made possible by the tendency of liquid bismuth to scavenge gold from significantly under-saturated fluids. Infiltrating gold-undersaturated fluids can dissolve gold not in contact with bismuth, which can then be preferentially redeposited upon encountering a bismuth droplet, enhancing the correlation between the two elements. A long-lived and focused fluid flow system would maximize the efficiency of this ore zone refining process, which is likely to be relevant to gold deposition at a range of deposit types.

Native gold and ore mineral inclusions in detrital zircon and quartz from the early precambrian quartzites and quartz gravelstones of the Karelian Craton

The study of solid mineral inclusions in detrital hydrothermal and hydrothermally altered zircons and quartz from Archaean and Palaeoproterozoic (Sumian and Jatulian) terrigenous quartz-rich clastic rocks of the Karelian Craton on a VEGA II LSH-TESKAN microanalyzer has revealed, for the first time, micron-sized native gold inclusions and associated syngenetic inclusions of ore minerals, such as galena, sphalerite, pyrite, chalcopyrite, molybdenite, molybdoscheelite, native bismuth and cerussite, as well as barite and complex hydroaluminophosphates of the goyacite-gorceixite-florencite-plumbogummite group. This mineral association in detrital material could indicate the ore-forming nature of its quartz vein source. These data, together with the earlier results of the local isotopic (SHRIMP-II and LA-ICP-MS) dating of these and similar heterogeneous detrital zircons, are indicative of several hydrothermal events, dated at 3.3, 3.15–2.9 and 2.76–2.65 Ga, which occurred in the region in Archaean time. The two latter ages are consistent with the time of formation of quartz vein ore systems with some of which gold ore-forming processes were associated.