Phase relations in the systems Ag2S-Cu2S-PbS and Ag2S-Cu2S-Bi2S3 and their mineral assemblages

Phase relations in the ternary systems Ag₂S-Cu₂S-PbS and Ag₂S-Cu₂S-Bi₂S₃ were studied using the silica vacuum technique. In the system Ag₂S-Cu₂S-Bi₂S₃ the phase relations are dominated by join-lines from galena to f.c.c. (Ag_x Cu_2−xS) and b.c.c. (Cu_x Ag_2−xS) at 500°C. With decreasing temperature, galena can coexist with all the phases on the Ag₂S-Cu₂S join. There are six solid solutions, and one new phase, i.e., “C” whose composition is Ag_1.1 Cu_4.8Bi_5.8S₁₂ in the system Ag₂S-Cu₂S-Bi₂S₃ at 500°C. The pavonite (AgBi₃S₅) contains 14 mole% Cu₂S in solid solution, but only 3.0 mole% Ag₂S in CuBi₃S₅ solid solution. The Cu₃Bi₅S₉ ss and wittichenite (Cu₃BiS₃) ss can form join-lines with pavonite as and have the maximum contents of 9.0 and 18 mole% Ag₂S. The most striking feature is the presence of bejaminite as a stable phase with a chemical formula of Ag₂Bi₄S₇ on the Ag₂S-Bi₂S₃ join. AgBiS₂ of the PbS type occupies a fairly large field with a maximum of 23 mole% Cu₂S.     

Ag_2S-Cu_2S-PbS-Bi_2S_3四元体系相关系研究(Ⅰ):相图和相关系

对Ag_2S-Cu_2S-PhS-Bi_2S_3四元体系500℃相图研究表明,整个体系相关系受十个组分范围变化大的固溶体和一个液相区控制。它们是:块硫铋银矿、铜银铅铋矿、硫铋铅矿、富硫铋铅矿、辉铋矿-针硫铋铅矿、方铅矿-杂硫铋银矿、硫铋铜矿和人工合成相CuBi_3S_5、Cu_3Bi_5S_8及新相“C”。此外体系内稳定的相是四元系端元相和辉铅铋矿。     

A microscopic study of synthetic PbS-Rich homologues nPbS-mBi2S3

The PbS-Bi₂S₃ join was studied up to 25 mole percent Bi₂S₃ by electron microscopy and diffraction. It was found that Bi₂S₃ can be incorporated into the PbS matrix by tropochemical twinning, forming isolated {113}_PbS microtwins, or after clustering of these defects, lamellar twinned regions. Only two known mineral members of the homologous series (lillianite Pb₃Bi₂S₆ and heyrowskyite Pb₆Bi₂S₉) were found to be stable in this part of the PbS-Bi₂S₃ join, while irregularly spaced twin bands within these two structures were observed where deviations in the PbS/Bi₂S₃ ratio from 6/1 and 3/1, respectively, took place. No ordered intergrowth members were found between heyrowskyite and lillianite. The difference between the PbS-Bi₂S₃ join and the analogous MnS-Y₂S₃ one was attributed to the lone pair of nonbonded electrons from the Bi³⁺ ions, which tends to concentrate these ions in the vicinity of the twin planes.     

Two Se-bearing Ag–Bi Sulphosalts, Benjaminite and Matildite from the Ikuno Deposits, Hyogo Prefecture, Japan –Au–Ag Mineralization in Polymetallic Zone

Abstract: Se-bearing benjaminite and matildite are described from the polymetallic zone of the Ikuno deposits, Japan. The former is the first occurrence in Japan, and is from two separate veins, the Nanten and Daimaru, while the locality of the latter could not be specified. The empirical formulae of two benjaminites based on 22 atoms are (Ag_{2. 74}Cu_{0. 24})_{Σ2. 98}(Bi_{7. 00}Sb_{0. 01})_{Σ7. 01}(S_{10. 89}Se_{1. 12})_{Σ12. 01} (Nanten) and (Ag_{2. 90}Cu_{0. 10})_{Σ3. 00}(Bi_{6. 74}Pb_{0. 18}Sb_{0. 07})_{Σ6. 99}(S_{11. 68}Se_{0.33)Σ12. 01} (Daimaru), leading to the validation of the formula Ag₃Bi₇S₁₂ as the ideal one for benjaminite, and that of matildite based on 4 atoms is Ag_{1. 00}Bi_{1. 00}(S_{1. 78}Se_{0. 22})Σ_{2. 00}. These designate the substitution of Se for S in all of them, where Se is preferentially incorporated into these Ag-Bi sulphosalts. The unit-cell parameters of them and matildite are: a 13. 272, b 4. 037, c 20. 185 Å, and β 103. 16° (Daimaru), a 13. 270, b 4. 040, c 20. 273 Å, and β103. 17° (Nanten); and a 4. 0670, c 18. 996 Å, respectively. The products of Au-Ag mineralization in the Ikuno polymetallic vein-type deposits also occur as such Ag-Bi sulfosalts as benjaminite and matildite, in addition to pavonite, “treasurite derivative” and “electrum” with cassiterite in the polymetallic zone, and also do as “electrum”, acanthite, and pyrargyrite-proustite in the Au-Ag zone. The significant quantity of the Ag-Bi sulfosalts does not violate the zoning occupying the outermost part of the zonal distribution of ores in the deposits.     

Electronic structures of sulfide minerals — Theory and experiment

The sulfide minerals exhibit a rich diversity in sturctural chemistry and in electrical, magnetic and other physical properties. Models based on molecular orbital theory and incorporating some elements of band theory can be developed to describe the diverse valence electron behavior in these minerals. Qualitative models can be proposed on the basis of observed properties, and the models can be tested and refined using experimental data from X-ray emission and X-ray photoelectron spectroscopy and quantum mechanical calculations performed on cluster units which form the basic building blocks of the crystals. This approach to chemical bonding in sulfide minerals is illustrated for binary non-transition metal sulfides (ZnS, CdS, HgS, PbS), binary transition metal sulfides (FeS₂, CoS₂, NiS₂, CuS₂ ZnS₂) and more complex sulfides (CuFeS₂, Cu₂S, Ag₂S, CuS, Co₃S₄, CuCo₂S₄, Fe₃S₄). The relationship between qualitative and quantitative theories is reviewed with reference to the pyrite-marcasite-arsenopyrite-loellingite series of minerals. Application of the models to understanding structure-determining principles, relative stabilities, solid solution limits and properties such as color, reflectance and hardness are discussed.     

Chemistry of some Pb-(Cu,Fe)-(Sb,Bi sulfosalts from France and Portugal. Implications for the crystal chemistry of lead sulfosalts in the Cu-poor part of the Pb2S2-Cu2S-Sb2S3-Bi2-Bi2S3 system

Electron microprobe analysis of Pb-Cu(Fe)-Sb-Bi sulfosalts from Bazoges and Les Chalanches (France), and Pedra Luz (Portugal), give new data about (Bi, Sb) solid-solution and incorporation of the minor elements Cu, Fe or Ag in jaskolskiite, and in izoklakeite-giessenite and kobellite-tintinaite series. Jaskolskiite from Pedra Luz has high Sb contents (from 17.9 to 20.7 wt.%), leading to the extended general formula: Cu _x Pb_2+x (Sb_1–y Bi _y )_2–x S₅, with 0.10 x 0.22 and 0.19 y 0.41. Fe-free, Bi-rich izoklakeite from Bazoges has high Ag contents (up to 2.2 wt. %), leading to the simplified formula Cu₂Pb₂₂Ag₂(Bi, Sb)₂₂S₅₇; in Les Chalanches it contains less Ag content (1.2 wt.%), but has an excess of Cu that gives the formula: Cu_2.00 (Cu_0.49Ag_1.18)_=1.67Pb_22.70(Bi_12.63Sb_8.99)_=21.62S_57.27.In tintinaite from Pedra Luz, the variation of the Fe/Cu ratio can be explained by the substitution: Cu + (Bi, Sb) Fe + Pb; Fe-free kobellite from Les Chalanches has a Cu-excess, corresponding to the formula Cu_2.81Ag_0.54Pb_9.88(Bi_10.37Sb_5.21)_=15.38S_35.09. Eclarite from the type locality, structurally related to kobellite, shows a Cu excess too. In natural samples of the kobellite homologous series, Fe is positively correlated with Pb, and its contents never exceed that of Cu. Ag substitutes for Pb, together with (Bi, Sb). Taking into account the possibility of Cu excess, but excluding formal Cu²⁺ and Fe³⁺, general formulae can be written:     

57Fe-Moessbauer spectra,electronic and crystal structure of members of the CuS2-FeS2 solid solution series

Members of the (Cu, Fe)S₂ solid solution crystallize in the pyrite structure type, space group Pa 3, Cu and Fe being statistically distributed on the metal sites. Within this series, a semiconductor to metal transition can be detected between 25 and 38 mole% CuS₂. Compositional dependent ⁵⁷Fe-Moessbauer spectra reveal Fe²⁺ in low-spin configuration. A minimum of the quadrupole splitting and the slope in the ⁵⁷Fe-isomer shift in the intermediate part of the system, near 30 mole% CuS₂, can be correlated with the onset of metallic conductivity, whereas the structural parameters are not influenced by this transition. The analysis of the compositional dependency of the quadrupole splitting, in comparison to the isotypic system (Co, Fe)S₂, leads to the conclusion that Cu in solid (Cu, Fe)S₂ compounds is Cu⁺ with an Ar -3 d¹⁰ electronic configuration.     

The Hiendelaencina mining district (Guadalajara,Spain)

The Hiendelaencina mining district (Guadalajara, Spain), includes the ore deposits of the Hiendelaencina, La Bodera and Congostrina areas. In this paper a general overview of this district is given, with special emphasis on the parageneses, mineralizing stages and chemical characteristics of the sulphides and sulphosalts. These deposits contain silver in Sb-rich sulphosalts such as freibergite, pyrargyrite, polybasite, stephanite, freieslebenite and the Bi-rich sulphosalt, aramayoite. Three mineralizing stages have been detected in Hiendelaencina and Congostrina: (1) As-Fe; (2) Cu-Zn-Fe-Sb-Ag; and (3) Pb-Sb-Ag (±Bi) but only two in La Bodera (stages 2 and 3). The average sulphosalt formulas are: freibergite (Cu_0.5 Ag_5.9) (Fe_1.42 Zn_0.66) (Sb_4.49 As_0.02) S₁₃; pyrargyrite Ag_3.38 Sb_1.0 S₃; polybasite (Ag_16.3Cu_0.15) (Sb_2.8 As_0.15) S₁₁; stephanite Ag_6.7 Sb_1.38 S₄; freieslebenite Ag_1.1 Sb_0.83 Pb_1.05 S₃ and aramayoite Ag_1.06 Bi_{0. 35} Sb_0.7 Pb_0.03 S₂. The compositional patterns of these sulphosalts (mainly based on the Sb/(Sb + Ag), Ag/ (Ag + Cu), Sb(Ag + As) and Ag/(Ag + Cu) ratios) are outlined, pointing broadly to similar tendencies in their chemistry and genetic conditions.     

AgS_2-Cu_2S-PbS-Bi_2S_3四元体系相关系研究(Ⅱ):铜银铅铋硫盐矿物结晶化学及分类

对Ag_2S-Cu_2S-PbS-Bi_2S_3四元体系内铋硫盐矿物的类质同象取代类型的研究表明,它共有四种:配对取代Ag(Cu)+Bi=2Pb,简单取代Ag=Cu,Bi(Pb)=Cu和Cu原子填隙(以平衡Bi或Pb为Cu取代时电价差)。研究还给出了体系内10个重要固溶体的成分及结晶参数之间的关系。对这些固溶体及铜、银、铅铋硫盐矿物结构特征、共生和共生长关系研究表明,它们可以分成四个系列:块硫铋银矿、硫铋铅矿、辉铋矿-针硫铋铅矿、贺硫铋铜矿。     

Ore mineralogy of the Waschgang gold-copper deposit,upper carinthia,Austria

Summary The gold-copper deposit at Waschgang (Southern Goldberg mountains, Upper Carinthia) belongs to a type of stratiform, dominantly pyritic deposit, which is hosted by greenschists (Alpine Kieslager;Friedrich, 1936). The ores occur as impregnations (ore type 1) and as massive ores (ore type 2) in prasinitic rocks of the Obere Schieferhülle of the Penninic unit. A N–S trending fault zone cuts the ore deposit to the W (Lettenkluft); the position of the displaced part is unknown.The mineralogical composition of type 1 ores is rather monotonous. Pyrite is the most important ore, minor components are chalcopyrite, bornite, sphalerite and magnetite. No visible native gold has been observed in this type of ore. Type 2 ores are dominated by chalcopyrite and are characterized by large amounts of visible native gold. The majority of these ores occur in the vicinity of the Lettenkluft.Type 2 ores carry a great variety of cogenetic mineral inclusions, of which several have been studied with the electron microprobe and investigated by X-ray methods. These include: tetradymite, Bi₂Te_1.81Se_0.13S; hessite, Ag₂Te; matildite, AgBiS₂; gladite, Cu_1.09Pb_1.14Bi_5.28S₉; krupkaite, CuPbBiS₆; pekoite, Cu_1.09Pb_0.97Bi_12.56S₁₈; (?) benjaminite, (Ag_2.72Cu_0.42)_3.14 (Bi_6.88Pb_0.12)₇(S_11.08Se_0.92)₁₂; pavonite, (Ag_0.74Cu_0.45)_1.19(Bi_2.86Pb_0.27)_3.13 (S_4.96Se_0.04)₅; (?) cupropavonite, (Cu_0.73Ag_0.4)_1.13(Bi_2.59Pb_0.83)_3.42S₅; and siegenite, (Ni_1.07Co_1.76Cu_0.19)_3.02S₄. Other components have been determined by qualitative and quantitative microscopy and include: bornite, idaite, mawsonite, sphalerite, millerite, magnetite, hematite, ilmenite, rutile and a variety of silicates.While the layered ore impregnations (type 1 ores) can be considered as being syngenetic with the associated volcanics of Jurassic age, a syn- to postkinematic (Alpidic) crystallization can be postulated for the type 2 ores. These ores are considered as remobilized and reconcentrated parts of the type 1 ores formed in tectonic stress zones. The crystallization of chalcopyrite and included ore minerals occurred during the cooling history of Alpidic metamorphism, for which in this region a maximum temperature of 500°C and pressures between 4–6 kb have been deduced from the mineral assemblage of the surrounding prasinites, consisting of albite with rims of oligoclase, epidote, chlorite, sphene and amphibole (Höck, 1980). Based onSpringer's limit of 300°C as approximately representing the maximum temperature at which natural members of the bismuthinite-aikinite mineral series have been formed, krupkaite and gladite with the intergrown pavonite type phases might have been deposited directly from solutions at or below 300°C. Unmixing of pekoite from gladite probably occurred at or below the same temperature.

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Zur Erzmineralogie der Gold-Kupfer-Lagerstätte Waschgang, Oberkärnten, Österreich

Zusammenfassung Die Gold-Kupfer-Lagerstätte Waschgang (südliche Goldberggruppe, Oberkärnten) ist dem Typus der stratiformen Kiesvererzungen in Grüngesteinen (Alpine Kieslager;Friedrich, 1936) zuzurechnen. Die Erzmineralisationen treten als stoffkonkordante Imprägnationen (Vererzungstypus 1) und als Derberze (Vererzungstypus 2) in Prasiniten der Oberen Schieferhülle des Penninikums auf. Das Erzlager wird im W an einer N–S streichenden Störung abgeschnitten; die Position des verworfenen W-Flügels ist nicht bekannt.Die Imprägnationserze sind in ihrer mineralogischen Zusammensetzung monoton; Pyrit als Haupterz überwiegt bei weitem die sporadischen Begleiter Kupferkies, Bornit, Sphalerit und Magnetit. Dieser Typus führt kein Freigold.Die von Kupferkies dominierten und an Freigold reichen Derberze treten vor allem im Bereich der Lettenkluft auf. Sie sind durch eine Vielfalt zum Teil komplex zusammengesetzter Einschlußminerale gekennzeichnet, von denen einige mittels Mikrosonde und röntgenographischer Methoden untersucht wurden: Tetradymit, Bi₂Te_1,81Se_0,13S; Hessit, Ag₂Te; Matildit, AgBiS₂; Gladit, Cu_1,09Pb_1,14Bi_5,28S₉; Krupkait, CuPbBiS₆; Pekoit, Cu_1,09Pb_0,97Bi_12,56S₁₈; (?) Benjaminit (Ag_2,72Cu_0,42)_3,14(Bi_6,88Pb_0,12)₇(S_11,08Se_0,92)₁₂; Pavonit, (Ag_0,74Cu_0,45)_1,19(Bi_2,86Pb_0,27)_3,13 (S_4,96Se_0,04)₅; (?) Cupropavonit, (Cu_0,73Ag_0,4)_1,13(Bi_2,59Pb_0,83)_3,42S₅; Siegenit, (Ni_1,07Co_1,76 Cu_0,19)_3,02S₄. Andere Mineralphasen wurden mittels qualitativer und quantitativer Mikroskopie bestimmt: Bornit, Idait, Mawsonit, Sphalerit, Millerit, Magnetit, Hämatit, Ilmenit, Rutil und Silikate.Während die stoffkonkordaten Imprägnationserze syngenetisch mit den assoziierten jurassischen Vulkaniten anzusehen sind, wird für die Derberze eine syn- bis postkinematische Kristallisation angenommen. Sie sind als remobilisierte und rekonzentrierte Teile der Imprägnationserze in tektonisch besonders beanspruchten Lagerstättenteilen anzusehen. Die Kristallisation des Kupferkieses und seiner Einschlußminerale erfolgte während der Abkühlungsphase der alpidischen Metamorphose, für die im betrachteten Gebiet eine Maximaltemperatur von ca. 500°C und Drucke zwischen 4–6 kb aufgrund der Petrologie der erzführenden Prasinite angenommen werden können. Die dafür maßgebende Paragenese besteht aus Albit mit Oligoklasrändern, Epidot, Chlorit, Sphen und Amphibol (Höck, 1980). Zieht man die vonSpringer (1971) ermittelte Stabilitätsgrenze von ±300°C für natürliche Mischkristalle der Bismuthinit-Aikinit-Reihe in Betracht, können für Krupkait und Gladit und den damit verwachsenen Pavonit-Phasen Bildungstemperaturen um oder unterhalb 300°C angenommen werden. Die Kristallisation dieser Minerale dürfte dabei direkt aus Lösungen erfolgt sein. Die als Entmischungsstrukturen interpretierten Gladit-Pekoit-Verwachsungen legen den Schluß einer primären Bildung beider Minerale als feste Lösung nahe, deren Zerfall vermutlich unterhalb von 300°C erfolgte.

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With 13 Figures

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Herrn em. Univ.-Prof. Dr.-Ing. O. M. Friedrich zum 80. Geburtstag in Dankbarkeit gewidmet

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This investigation forms part 2 of a major study on Genetic Types of Gold Deposits of the Alps.     

Mineralogy and mineral chemistry of Bi-minerals: Constraints on ore genesis of the Beiya giant porphyry-skarn gold deposit,southwestern China

The Beiya deposit, located in the Sanjiang Tethyan tectonic domain (SW China), is the third largest Au deposit in China (323 t Au @ 2.47 g/t). As a porphyry-skarn deposit, Beiya is related to Cenozoic (Himalayan) alkaline porphyries. Abundant Bi-minerals have been recognized from both the porphyry- and skarn- ores, comprising bismuthinite, Bi–Cu sulfosalts (emplectite, wittichenite), Bi–Pb sulfosalts (galenobismutite, cosalite), Bi–Ag sulfosalt (matildite), Bi–Cu–Pb sulfosalts (bismuthinite derivatives), Bi–Pb–Ag sulfosalts (lillianite homologs, galena-matildite series), and Bi chalcogenides (tsumoite, the unnamed Bi₂Te, the unnamed Ag₄Bi₃Te₃, tetradymite, and the unnamed (Bi, Pb)₃(Te, S)₄). Native bismuth and maldonite are also found in the skarn ores. The arsenopyrite geothermometer reveals that the porphyry Au mineralization took place at temperatures in the range of 350–450 °C and at log fS₂ in the range of − 8.0 to − 5.5, respectively. In contrast, the Beiya Bi-mineral assemblages indicate that the skarn ore-forming fluids had minimum temperatures of 230–175 °C (prevailing temperatures exceeding 271 °C) and fluctuating fS₂–fTe₂ conditions. We also model a prolonged skarn Au mineralization history at Beiya, including at least two episodes of Bi melts scavenging Au. We thus suggest that this process was among the most effective Au-enrichment mechanisms at Beiya.     

Evidence of sulfide melting and melt fractionation during amphibolite facies metamorphism of the Rajpura–Dariba polymetallic sulfide ores

Partial melting of sulfide ores during prograde metamorphism could have been more prevalent than generally accepted. However, identification of such melting is difficult as sulfide melts do not form glasses and the textures generated on quenching are obliterated due to the tendency of sulfides for ready recrystallization. The polymetallic base metal sulfide deposit at Rajpura–Dariba, Rajasthan, India is a typical stratiform ore metamorphosed to the middle amphibolite facies. The peak metamorphic temperature of 600 °C should have been sufficient to initiate sulfide melting as evident from experimental studies in the ZnS–PbS–Cu₂S–FeS₂–S system. Further, syn-metamorphic melting of the original SEDEX ore was abetted by the high f_S2 condition that prevailed as a consequence of barite dissolution. A Zn–Fe–S melt containing minor Pb, Sb and Cu but no Ag fractionated from an initial melt in the above system resulting in a residual immiscible sulfosalt-bearing PbS melt. The final metallic melts, represented by formation of dyscrasite (Ag₃Sb) from the sulfosalt-bearing melt and breithauptite (NiSb) or ullmannite (NiSbS) from the sulfosalt-absent melt, were a product of independent fractional crystallization of the immiscible sulfide and PbS–sulfosalt melts.     

Ag2(S,Se) solid solutions in the ores of the Rogovik gold-silver deposit (northeastern Russia)

The relationships and chemical compositions of silver sulfoselenides in the ores of the Rogovik gold-silver deposit (northeastern Russia) were studied to refine the low-temperature region of the Ag₂S-Ag₂Se phase diagram and identify contradictions between natural and experimental data. Two types of relationships between the phases of the system Ag₂S-Ag₂Se have been recognized using optical and scanning electron microscopy: (1) Se-acanthite and S-naumannite occur as monomineral microinclusions or fill cracks in the grains or the interstices of other minerals, and acanthite (free of impurities) forms rims on Fe-sphalerite; (2) Se-acanthite forms rims on S-naumannite. Electron probe microanalysis of silver sulfoselenides from the Rogovik ores revealed 0–7.9 wt.% Se in acanthite and 0–3.2 wt.% S in naumannite, which corresponds to the acanthite series Ag₂S-Ag₂S₀.₇₄Se₀.₂₆ and naumannite series Ag₂S₀.₂₈Se₀.₇₂-Ag₂Se. The composition ranges of the studied acanthite and naumannite series are wider than those of natural silver sulfoselenides from the Guanajuato (Mexico), Silver City (USA), Salida (Indonesia), and other deposits (Ag₂S-Ag₂S0.85Se0.₁5 and Ag₂S0.₁₂Se0.88-Ag₂Se, respectively) but are significantly narrower than the composition ranges of synthetic samples: Ag₂S-Ag₂S0.₄Se0.6 and Ag₂S0.3Se0.₇-Ag₂Se. The presence of intergrowths of two phases of the Ag₂S-Ag₂Se series in the form of Se-acanthite rims on S-naumannite in the Rogovik ores and the absence of three-phase intergrowths of silver sulfoselenides Ag₂S_1 -xSe_x from this and other deposits do not confirm the assumption on the existence of the third solid solution. The results of earlier studies of natural Ag₂(S,Se) solid solutions show the existence of two solid solutions (of the acanthite and naumannite series) in the Ag₂S-Ag₂Se system and confirm the experimental data. It is necessary to carry out a detailed examination of natural silver sulfoselenides falling in the interval from Ag2S0.4Se0.6 to Ag2S0.3Se0.7 in order to identify the limits of two-phase immiscibility.     

Pb−Bi−(Cu)-sulfosalts in Paleozoic gneisses and schists from Oberpinzgau,Salzgurg province,Austria

Summary Pb–Bi–(Cu)-sulfosalts occur as minor minerals widely distributed in rocks of the Penninic unit (gneisses, schists, metavolcanics, etc.), Oberpinzgau, Salzburg. The sulfosalts have been investigated by ore microscopy, X-ray diffraction and electron microprobe analysis. The phases identified are: heyrovskyite, cosalite (Moaralm, Sedl, and Wiesbachrinne in the Habach Valley), lillianite (Moaralm, Sedl; Modereck near the Fuscher Valley), galenobismutite (Bärenbad in the Hollersbach Valley) and Bi-bearing galena. Heyrovskyite (Moaralm) has a composition close to Pb₆Bi₂S₉, with Ag contents between 0.2 (Sedl) and 0.6 (Moaralm) wt.%. Lillianite has the composition Pb_2.86–2.91 Bi_2.08–2.17Ag_0.04–0.08 S₆, and cosalite, Pb_1.81–2.04 Bi_1.92–2.02 Ag_0.02–0.06 Cu_0.11–0.18S₅. The average chemical composition of galenobismutite is Pb_1.25Bi_1.6Sb_0.1Cu_0.1Ag_0.02Fe_0.1S₄. Needle-like inclusions of a joseite-type mineral, joseite-A (Bi,Pb)_4.01 Te_0.9S_2.08, and irregular to needle-like grains of native bismuth usually occur along the elongation direction of the lath-like galenobismutite crystals.The occurrences can be divided into two types: 1) stratiform Pb–Bi sulfosalts which occur only in the quartzite intercalations of the Paleozoic Habach unit (Frasl, 1958), and 2) alpidic vein type Pb–Bi sulfosalts which occur in quartz veins intersecting gneisses and are considered to be the remobilization products of the first type. Temperature of formation for heyrovskyite in this region is estimated at between 400±25°C and 500°C. Most probably, the assemblage heyrovskyite-lillianite-galena (Moaralm) was formed at or below 473°C.

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Pb–Bi–(Cu)-Sulfosalze in paläozoischen Gesteinen des Oberpinzgau, Salzburg, Österreich

Zusammenfassung Pb–Bi-Sulfosalze verschiedener Vorkommen des Oberpinzgau, Salzburg, wurden mittels Erzmikroskopie, röntgenographischer Methoden und Mikrosonde untersucht. Folgende Phasen wurden identifiziert: Heyrovskyit, Cosalit (Moaralm, Sedl und Wiesbachrinne; alle Habachtal), Lillianit (Moaralm, Sedl; Modereck nahe des Fuschertales), Galenobismutit (Bärenbad, Hollersbachtal) und Bi-hältiger Bleiglanz. Heyrovskyit (Moaralm) ist nahezu Pb₆Bi₂S₉, mit Ag-Gehalten zwischen 0,2 (Sedl) und 0.6 (Moaralm) Gew.%, Lillianit Pb_2,86–2,91Bi_2,08–2,17Ag_0,04–0,08S₆, und Cosalit Pb_1,81–2,04Bi_1,92–2,02Ag_0,02–0,06 Cu_0,11–0,18S₅. Galenobismutit ist Pb_1,25Bi_1,6Sb_0,1Cu_0,1Ag_0,02Fe_0,1S₄. Nadelige Einschlüsse von Joseit-A, (Bi, Pb)_4,01Te_0,9S_2,08, und unregelmäßige bis nadelige Körner von ged. Wismut treten entlang der Längsrichtung der Galenobismutit-Kristalle auf. Die Mineralisationen sind an stratiforme, sulfidreiche Quarzlagen (Typus 1, z. B. Bärenbad) oder an diskordante Quarzgänge (Typus 2; alle anderen Vorkommen) gebunden. Typus 1 tritt innerhalb der altpaläzozischen Habachserie (Frasl, 1958), Typus 2 in Randbereichen dieser zu den Gneismassen der Habachzunge (z. T. auch in letzteren) auf. Die dem Typus 2 zugerechneten Vererzungen werden als Remobilisationsprodukte der altpaläozoischen Mineralisationen (Typus 1) angesehen.Die Bildungstemperatur des Heyrovskyit dürfte im betrachteten Bereich zwischen 400±25°C und 500°C gelegen haben; eine Bildungstemperatur von 473°C oder wening darunter wird für die Assoziation Heyrovskyit-Lillianit-Bleiglanz in Anlehnung an experimentelle Untersuchungen vonSalanci undMoh (1969) angenommen.

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With 4 Figures

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This investigation forms part of a wider study Genetic types of gold deposits in the Alps.     

Phase relations and mineral assemblages in the Ag-Bi-Pb-S system

Phase relations within the Ag-Bi-S, Bi-Pb-S, and Ag-Pb-S systems have been determined in evacuated silica tube experiments. Integration of experimental data from these systems has permitted examination and extrapolation of phase relations within the Ag-Bi-Pb-S quaternary system. — In the Ag-Bi-S system liquid immiscibility fields exist in the metal-rich portion above 597±3°C and in the sulfur-rich portion above 563±3°C. Ternary phases present correspond to matildite (AgBiS₂) and pavonite (AgBi₃S₅). Throughout the temperature range 802±2°C to 343±2°C the assemblage argentite (Ag₂S) + bismuth-rich liquid is stable; below 343°C this assemblage is replaced by the assemblage silver + matildite. — Five ternary phases are stable on the PbS-Bi₂S₃ join above 400°C — phase II (18 mol-% Bi₂S₃), phase III (27 mol-% Bi₂S₃), cosalite (33.3 mol-% Bi₂S₃), phase IV (51 mol-% Bi₂S₃), and phase V (65 mol-% Bi₂S₃). Phase IV corresponds to the mineral galenobismutite and is stable below 750±3°C. Phases II, III, and V do not occur as minerals, but typical lamellar and myrmekitic textures commonly observed among the Pb-Bi sulfosalts and galena evidence their previous existence in ores. Phase II and III are stable from 829±6°C and 816±6°C, respectively, to below 200°C; Phase V, stable only between 730±5°C and 680±5°C in the pure Bi-Pb-S system is stabilized to 625±5°C by the presence of 2% Ag₂S. Experiments conducted with natural cosalites suggest that this phase is stable only below 425±25°C in the presence of vapor. — In the Ag-Pb-S system the silver-galena assemblage is stable below 784±2°C, whereas the argentite + galena mineral pair is stable below 605±5°C. — Solid solution between matildite and galena is complete above 215±15°C; below this temperature characteristic Widmanstätten structure-like textures are formed through exsolution. Schematic phase relations within the quaternary system are presented at 1050°C, at 400°C, and at low temperature.

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Zusammenfassung Die Phasenbeziehungen in den Systemen Ag-Bi-S, Bi-Pb-S und Ag-Pb-S wurden durch Versuche in evakuierten Quarzglasröhrchen bestimmt. Die Auswertung aller experimentellen Daten gestattete eine Extrapolation der Phasenbeziehungen im quaternären System Ag-Bi-Pb-S. — Im System Ag-Bi-S besteht ein Zwei-Schemlzenfeld im metallreichen Teil über 597±3°C und im schwefelreichen Teil über 563±3°C. Die ternären Phasen entsprechen den Mineralien Schapbachit (AgBiS₂) und Pavonit (AgBi₃S₅). Zwischen 802±2°C und 343±2°C ist die Paragenese Silberglanz (Ag₂S) + Bi-reiche Schmelze stabil; unterhalb 343°C wird sie jedoch ersetzt durch die Paragenese Silber + Schapbachit. — Fünf ternäre Phasen sind stabil im Schnitt PbS-Bi₂S₃ oberhalb von 400°C: Phase II (18 Mol-% Bi₂S₃), Phase III (27 Mol-% Bi₂S₃), Cosalite (33.3 Mol-% Bi₂S₃), Phase IV (51 Mol-% Bi₂S₃) und Phase V (65 Mol-% Bi₂S₃). Phase IV entspricht dem Mineral Galenobismutit und ist stabil unterhalb 750±3°C. Die Phasen II, III und V kommen zwar nicht in der Natur vor, jedoch weisen typische myrmekitische und lamellare Gefüge, die man häufig in Pb-Bi-Sulfosalzen und deren Verwachsungen mit Bleiglanz beobachtet, auf die ehemalige Existenz solcher Phasen in diesen Erzen hin. Die Phasen II und III sind stabil von 829±6°C bzw. 816±6°C bis unter 200°C. Die Phase V, die im reinen System Bi-Pb-S zwischen 730±5°C und 680±5°C auftritt, wird in Gegenwart von 2% Ag₂S stabilisiert bis herab zu 625±5°C. Versuche mit natürlichen Cosaliten lassen darauf schließen, daß diese Phase nur unterhalb 425±25°C in Gegenwart einer Gasphase stabil ist. — Im System Ag-Pb-S ist die Paragenese Silber-Bleiglanz unterhalb von 784±2°C stabil, die Paragenese Silberglanz-Bleiglanz dagegen unterhalb 605±5°C. — Die Mischkristallreihe von Schapbachit und Bleiglanz ist vollständig oberhalb 215±15°C; unterhalb dieser Temperatur entstehen charakteristische Entmischungsgefüge ähnlich den Widmannstättenschen Figuren. Für das quaternäre System werden schematische Phasenbeziehungen für 1050°C, 400°C und eine noch tiefere Temperatur gegeben.

     

Zur Kristallstruktur des Bismuthinits,Bi2S3

Zusammenfassung Es wurde eine Bestimmung der Kristallstruktur des Bismuthinits Bi₂S₃, die bisher nur als Analogie der Antimonitstruktur bekannt war, durchgeführt. Es zeigte sich, daß die Kristallstruktur des Bismuthinits weitgehend mit der von Antimonit übereinstimmt. Die Koordinationspolyeder sind allerdings regelmäßiger als beim Sb₂S₃ und bei einem der beiden kristallographisch unabhängigen Bi-Atome zeigt sich bei genauer Betrachtung ein deutlicher Unterschied, so daß die Koordination von diesem als 3+3+1 gegenüber 3+2+1 beim Antimonit bezeichnet werden kann.

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The crystal structure of bismuthinite

Summary The crystal structure of bismuthinite Bi₂S₃ was determined. It showed that the analogy to the structure of stibnite is correct in general. The coordination polyhedra are more regular compared to those in Sb₂S₃. One of the crystallographic independent Bi-atoms shows a distinct difference in coordination, 3+3+1, compared to the equivalent atom in antimonite, 3+2+1.

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Mit 1 Abbildung     

Experimental investigation of the Ag-TI-Bi-Sb-S system

Summary Polymetallic ore deposits of low temperature origin often contain thallium as a minor element. By means of modern analytical methods numerous new T1 minerals are described, but their coexistence and equilibria are not investigated yet.The equilibria at 200°C of the quasi-quaternary system Ag₂S-Tl₂S-Sb₂-Sb₂S₃-Bi₂S₃ and the corresponding subsystems were studied. The system Ag₂S-Tl₂S-Sb₂S₃-Bi₂S₃ contains only one quasiquaternary phase, AgTlSbBiS₄, which is connected by tie-lines with all quasiternary phases in the system (Ag₄Sb₃BiS₈ and Ag₃Tl₃Sb₂S₆) and with most quasibinary phases: SbBiS₃, weissbergite (TlSbS₂), (TlBiS₂, pyrargyrite (Ag₃SbS₃), miargyrite (AgSbS₂) and matildite (AgBiS₂). This phase diagram makes it possible to investigate all important naturally occurring parageneses of Ag and Tl sulphosalts containing Sb and Bi.

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Die experimentelle Untersuchung des Ag-TI-Sb-Bi-S Systems

Zusammenfassung In polymetallischen Sulfiderzen niedriger Bildungstemperaturen sind Spuren von Thallium fast immer nachweisbar. In jüngster Zeit wurde mittels moderner Analysentechniken eine Reihe neuer Thalliumminerale entdeckt, charakteristische Paragenesen sind bisher und Phasengleichgewichte jedoch unerforscht.In einer experimentellen Studie wurde das quasi-quaternäre System Argentit (Ag₂S)-Carlinit (Tl₂S)-Antimonglanz (Sb₂S₃)-Wismutglanz (Bi₂S₃) bei 200 °C untersucht. Es enthält nur eine quasi-quaternäre Phase AgTlSbBiS₄, welche durch Konoden mit den quasi-ternären Phasen Ag₄Sb₃BiS₈ und Ag₃Tl₃Sb₂S₆, sowie mit den quasi-binären Phasen Pyrargyrit (Ag₃SbS₃), Miargyrit (AgSbS₂), Schapbachit (Matildit, AgBiS₂), Weissbergit (TlSbS₂), TlBiS₂ und SbBiS₃ verknüpft ist. Das vorliegende Phasendiagramm ermöglichtes die Phasenbeziehungen natürlich vorkommender Ag- und Tl-Sulfosalze, die Sb und Bi enthallen, darzustellen.

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With 5 Figures

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Deceased     

Phase equilibrium study in the system Cu2S-PbS-Sb2S3: non-stoichiometry in sulfosalts and isothermal variation in sulfur fugacity

Evacuated silica tube experiments (+halide flux) were conducted in portions of the system Cu₂S-PbS-Sb₂S₃ at 440°C, using two-pyrrhotite indicator method to measure the sulfur fugacity. Product phases were identified by optical and X-ray powder diffraction methods supplemented with microprobe analyses. In addition to the previously reported mineral phases, famatinite (Cu₃SbS₄) appears to be a stable phase in the Sb₂S₃-rich portion of the system. Microprobe data indicate that almost all the sulfosalts depart from stoichiometry. Copper in Pb-Sb sulfosalts and Pb in chalcostibite and skinnerite are indicative of the coupled substitution 2Pb²⁺=Cu⁺+Sb³⁺. Pb-solubility in skinnerite and Cu-solubility in zinkenite are dependent on the initial bulk composition of the charges. The compositions of meneghinite and boulangerite compare well with their natural analogues. The maximum isothermal variation of logf _{s 2} falls in the range of-6.36 (1.06)logf _{s 2}11.12 (0.30). The experimentally derived logf _{s 2} values for some two phase assemblages, compare reasonably well with the respective minimum logf _{s 2} values calculated by the method of Craig and Barton (1973). The stable coexistence of famatinite with zinkenite plus stibnite instead of chalcostibite may be described by the sulfidation reaction: 3CuSbS₂+1/2 S₂=Cu₃SbS₄+Sb₂S₃.     

江西盘古山-黄沙黑钨矿石英脉矿床铋硫盐矿物再研究

江西于都盘古山－黄沙的铋硫盐矿物的种属较多,前已查明的有１７种,其中有未定久铋硫盐矿物２种,主要是ＰｂＳ－Ｂｉ２Ｓ３系列和ＰｂＳ－Ａｇ２Ｓ－Ｂｉ２Ｏ３系列的铋硫盐矿物。