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R. T. M. Dobbe - One of the best experts on this subject based on the ideXlab platform.
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Tellurides, selenides and associated Minerals in the Tunaberg copper deposits, SE Bergslagen, Central Sweden
Mineralogy and Petrology, 1991Co-Authors: R. T. M. DobbeAbstract:The Tunaberg copper deposits, SE Bergslagen, Central Sweden, locally contain tellurium and Selenium Minerals not previously reported from this locality. Hessite, tellurobismutite, tellurium, tetradymite, kawazulite, clausthalite and selenian galena are found as inclusions in bornite and chalcopyrite in a skarn sulphide ore with Cd-rich sphalerite, cobaltite and cobalt pentlandite (assemblage A), and in a skarn iron ore with magnetite (assemblage B). Accessory Minerals included in bornite and chalcopyrite are auriferous silver, electrum, carrollite, stannoidite, mawsonite, parkerite, aikinite, emplectite, wittichenite and two unidentified Cu-Ag-Bi sulphosalts.
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Tellurides, selenides and associated Minerals in the Tunaberg copper deposits, SE Bergslagen, Central Sweden
Mineralogy and Petrology, 1991Co-Authors: R. T. M. DobbeAbstract:Die Kupferlagerstätten von Tunaberg, SE Bergslagen, Zentral-Schweden enthalten stellenweise Tellur-und Selen-Minerale, die hier bisher nicht bekannt waren. Hessit, Tellurobismutit, gediegen Tellur, Tetradymit, Kawazulit, Clausthalit und selen führender Bleiglanz kommen als Einschlüsse in Bornit und Kupferkies in einem Skarn-Sulphiderz mit cadmiumreichem Sphalerit, Cobaltit und Cobalt-Pentlantit (Paragenese A), und in einem Eisenskarnerz mit Magnetit (Paragenese B) vor. Akzessorische Minerale in Bornit und Calcopyrit sind goldführendes Silber, Electrum, Carrollit, Stannoidit, Mawsonit, Parkerit, Aikinit, Emplektit, Wittichenit und zwei noch nicht identifizierte Cu-Ag-Bi Sulphosalze. Die Telluride, Selenide, und assoziierte Minerale in der Paragenee A kommen teils als frühe Kristalliten und teils als Segregationen aus einer Hoch-Temperatur Bornit-“solid solution” vor, die auf metamorphogene skarnbildende Erzlösungen zurückgehen. dürfe. Diese Vorgänge fallen zeitlich mit der Bildung von Diopsid oberhalb von 475°C und von retrogradem Tremolit oberhalb von 420°C zusammen. Bi-Te-Se-Pb-Ag-Minerale der Paragenese B kristallisierten bei niedrigerem aS_2 und höherem aCu^+ aus residualen hydrothermalen Lösungen metamorphen Ursprunges. The Tunaberg copper deposits, SE Bergslagen, Central Sweden, locally contain tellurium and Selenium Minerals not previously reported from this locality. Hessite, tellurobismutite, tellurium, tetradymite, kawazulite, clausthalite and selenian galena are found as inclusions in bornite and chalcopyrite in a skarn sulphide ore with Cd-rich sphalerite, cobaltite and cobalt pentlandite (assemblage A), and in a skarn iron ore with magnetite (assemblage B). Accessory Minerals included in bornite and chalcopyrite are auriferous silver, electrum, carrollite, stannoidite, mawsonite, parkerite, aikinite, emplectite, wittichenite and two unidentified Cu-Ag-Bi sulphosalts. The tellurides, selenides and associated Minerals in assemblage A occur, in part, as early crystallites and, in part, as segregations from a high-temperature bornite solid solution, which presumably crystallized from metamorphogenic skarn-forming ore solutions, about contemporaneous with the formation of diopside above 475°C and of retrogressive tremolite above 420°C. Minerals of Bi-Te-Se-Pb-Ag in assemblage B presumably crystallized at lower aS_2 and higher aCu^+ from residual hydrothermal solutions of similar metamorphogenic origin.
Jiri Pešek - One of the best experts on this subject based on the ideXlab platform.
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The occurrence and origin of Selenium Minerals in Se-rich stone coals, spoils and their adjacent soils in Yutangba, China
Chemical Geology, 2012Co-Authors: Jian Ming Zhu, Thomas M. Johnson, Robert B. Finkelman, Bao Shan Zheng, Ivana Sýkorová, Jiri PešekAbstract:Abstract Several Se-bearing Minerals have been identified in Se-rich stone coal, spoils, and their adjacent organic-rich soils in Yutangba of Enshi, China, where human Se toxicity occurred in the 1960s. These Minerals mainly include native Se (Se 0 ), krutaite (CuSe 2 ), klockmannite (CuSe), mandarinoite (Fe 2 (SeO 3 ) 3 ·6H 2 O), Se-bearing chalcopyrite (CuFe(Se, S) 2 ), and pyrite (Fe(Se,S) 2 ). The assemblage of native Se, krutaite, klockmannite, and Se-bearing pyrite and chalcopyrite is primarily present in the stone coal near a fault plane, while the assemblage of native Se and krutaite is found in the Se-rich carbonaceous mudstone and organic-rich soils which are 60 m away from the stone coal exposure. The assemblage of mandarinoite and native Se is present in abandoned stone coal spoils, where natural combustion occurred. Native Se is quite extensive in the stone coal spoils and nearby soils derived from them. The co-occurrence of Cu–Se Minerals and native Se indicates that these Minerals could have formed under a relatively acidic and reducing environment below 220 °C, and suggests that Cu could play a significant role in fixing reduced Se ions in the acidic, organic-rich surface environment. Furthermore, the occurrence of mandarinoite suggests that iron-oxides constrain the geochemical behavior of Se in oxidizing environments. Our observations provide new insights into the mechanisms of Se fixation and accumulation during weathering of Se-rich rocks.
A V Vishnevsky - One of the best experts on this subject based on the ideXlab platform.
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thermodynamics of arsenates selenites and sulfates in the oxidation zone of sulfide ores xiv Selenium Minerals in the oxidation zone of the yubileynoe massive sulfide deposit the south urals
Geology of Ore Deposits, 2018Co-Authors: A V Vishnevsky, M. V. Charykova, V. G. Krivovichev, E. V. Belogub, Ivan A BlinovAbstract:Selenium is one of the most important minor elements in massive sulfide ores. This study focuses on Selenium Minerals present in the oxidation zone of the Yubeleinoe massive sulfide deposit, the South Urals, Russia: clausthalite (PbSe), tiemannite (HgSe), and naumannite (Ag2Se). These Minerals are associated with goethite and siderite. Thermodynamic modeling was used to estimate the physicochemical parameters of selenide stability and the possible formation of Pb, Hg, and Ag selenites as a result of sulfide ore oxidation. The Eh–pH diagrams for the Fe–S–CO2–H2O and Fe–Se–CO2–H2O systems were calculated to estimate the physicochemical formation conditions of the Yubileinoe oxidation zone, as well as for the M–Se–Н2О and M–S–H2O (M = Hg, Pb, Ag) systems. The physicochemical parameters of clausthalite, naumannite, and tiemannite stability are consistent with these conditions. Only the formation of PbSeO3 is theoretically possible among Pb, Ag, and Hg selenites.
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The Thermodynamics of Selenium Minerals in Near-Surface Environments
Minerals, 2017Co-Authors: V. G. Krivovichev, M. V. Charykova, A V VishnevskyAbstract:Selenium compounds are relatively rare as Minerals; there are presently only 118 known mineral species. This work is intended to codify and systematize the data of mineral systems and the thermodynamics of Selenium Minerals, which are unstable (selenides) or formed in near-surface environments (selenites), where the behavior of Selenium is controlled by variations of the redox potential and the acidity of solutions at low temperatures and pressures. These parameters determine the migration of Selenium and its precipitation as various solid phases. All Selenium Minerals are divided into four groups—native Selenium, oxide, selenides, and oxysalts—anhydrous selenites (I) and hydrous selenites and selenates (II). Within each of the groups, Minerals are codified according to the minimum number of independent elements necessary to define the composition of the mineral system. Eh–pH diagrams were calculated and plotted using the Geochemist’s Workbench (GMB 9.0) software package. The Eh–pH diagrams of the Me–Se–H2O systems (where Me = Co, Ni, Fe, Cu, Pb, Zn, Cd, Hg, Ag, Bi, As, Sb, Al and Ca) were plotted for the average contents of these elements in acidic waters in the oxidation zones of sulfide deposits. The possibility of the formation of Zn, Cd, Ag and Hg selenites under natural oxidation conditions in near surface environments is discussed.
V. G. Krivovichev - One of the best experts on this subject based on the ideXlab platform.
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Selenium Minerals: Structural and Chemical Diversity and Complexity
Minerals, 2019Co-Authors: V. G. Krivovichev, Sergey V. Krivovichev, M. V. CharykovaAbstract:Chemical diversity of Minerals containing Selenium as an essential element has been analyzed in terms of the concept of mineral systems and the information-based structural and chemical complexity parameters. The study employs data for 123 Se mineral species approved by the International Mineralogical Association as of 25 May 2019. All known Selenium Minerals belong to seven mineral systems with the number of essential components ranging from one to seven. According to their chemical features, the Minerals are subdivided into five groups: Native Selenium, oxides, selenides, selenites, and selenates. Statistical analysis shows that there are strong and positive correlations between the chemical and structural complexities (measured as amounts of Shannon information per atom and per formula or unit cell) and the number of different chemical elements in a mineral. Analysis of relations between chemical and structural complexities provides strong evidence that there is an overall trend of increasing structural complexity with the increasing chemical complexity. The average structural complexity for Se Minerals is equal to 2.4(1) bits per atom and 101(17) bits per unit cell. The chemical and structural complexities of O-free and O-bearing Se Minerals are drastically different with the first group being simpler and the second group more complex. The O-free Se Minerals (selenides and native Se) are primary Minerals; their formation requires reducing conditions and is due to hydrothermal activity. The O-bearing Se Minerals (oxides and oxysalts) form in near-surface environment, including oxidation zones of mineral deposits, evaporites and volcanic fumaroles. From the structural viewpoint, the five most complex Se Minerals are marthozite, Cu(UO2)3(SeO3)2O2·8H2O (744.5 bits/cell); mandarinoite, Fe2(SeO3)3·6H2O (640.000 bits/cell); carlosruizite, K6Na4Na6Mg10(SeO4)12(IO3)12·12H2O (629.273 bits/cell); prewittite, KPb1.5ZnCu6O2(SeO3)2Cl10 (498.1 bits/cell); and nicksobolevite, Cu7(SeO3)2O2Cl6 (420.168 bits/cell). The mechanisms responsible for the high structural complexity of these Minerals are high hydration states (marthozite and mandarinoite), high topological complexity (marthozite, mandarinoite, carlosruizite, nicksobolevite), high chemical complexity (prewittite and carlosruizite), and the presence of relatively large clusters of atoms (carlosruizite and nicksobolevite). In most cases, Selenium itself does not play the crucial role in determining structural complexity (there are structural analogues or close species of marthozite, mandarinoite, and carlosruizite that do not contain Se), except for selenite chlorides, where stability of crystal structures is adjusted by the existence of attractive Se–Cl closed-shell interactions impossible for sulfates or phosphates. Most structurally complex Se Minerals originate either from relatively low-temperature hydrothermal environments (as marthozite, mandarinoite, and carlosruizite) or from mild (500–700 °C) anhydrous gaseous environments of volcanic fumaroles (prewittite, nicksobolevite).
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thermodynamics of arsenates selenites and sulfates in the oxidation zone of sulfide ores xiv Selenium Minerals in the oxidation zone of the yubileynoe massive sulfide deposit the south urals
Geology of Ore Deposits, 2018Co-Authors: A V Vishnevsky, M. V. Charykova, V. G. Krivovichev, E. V. Belogub, Ivan A BlinovAbstract:Selenium is one of the most important minor elements in massive sulfide ores. This study focuses on Selenium Minerals present in the oxidation zone of the Yubeleinoe massive sulfide deposit, the South Urals, Russia: clausthalite (PbSe), tiemannite (HgSe), and naumannite (Ag2Se). These Minerals are associated with goethite and siderite. Thermodynamic modeling was used to estimate the physicochemical parameters of selenide stability and the possible formation of Pb, Hg, and Ag selenites as a result of sulfide ore oxidation. The Eh–pH diagrams for the Fe–S–CO2–H2O and Fe–Se–CO2–H2O systems were calculated to estimate the physicochemical formation conditions of the Yubileinoe oxidation zone, as well as for the M–Se–Н2О and M–S–H2O (M = Hg, Pb, Ag) systems. The physicochemical parameters of clausthalite, naumannite, and tiemannite stability are consistent with these conditions. Only the formation of PbSeO3 is theoretically possible among Pb, Ag, and Hg selenites.
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The Thermodynamics of Selenium Minerals in Near-Surface Environments
Minerals, 2017Co-Authors: V. G. Krivovichev, M. V. Charykova, A V VishnevskyAbstract:Selenium compounds are relatively rare as Minerals; there are presently only 118 known mineral species. This work is intended to codify and systematize the data of mineral systems and the thermodynamics of Selenium Minerals, which are unstable (selenides) or formed in near-surface environments (selenites), where the behavior of Selenium is controlled by variations of the redox potential and the acidity of solutions at low temperatures and pressures. These parameters determine the migration of Selenium and its precipitation as various solid phases. All Selenium Minerals are divided into four groups—native Selenium, oxide, selenides, and oxysalts—anhydrous selenites (I) and hydrous selenites and selenates (II). Within each of the groups, Minerals are codified according to the minimum number of independent elements necessary to define the composition of the mineral system. Eh–pH diagrams were calculated and plotted using the Geochemist’s Workbench (GMB 9.0) software package. The Eh–pH diagrams of the Me–Se–H2O systems (where Me = Co, Ni, Fe, Cu, Pb, Zn, Cd, Hg, Ag, Bi, As, Sb, Al and Ca) were plotted for the average contents of these elements in acidic waters in the oxidation zones of sulfide deposits. The possibility of the formation of Zn, Cd, Ag and Hg selenites under natural oxidation conditions in near surface environments is discussed.
Liu Jiajun - One of the best experts on this subject based on the ideXlab platform.
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Geochemistry of the Yutangba Se deposit in western Hubei, China
Chinese Journal of Geochemistry, 2004Co-Authors: Feng Caixia, Liu Jiajun, Hu Ruizhong, Liu ShenAbstract:The Yutangba Se deposit is a rare high-Se deposit in the world and it is well known for its high contents of Se, which reach 8590 × 10−6. The ore-hosted rocks are dominated by cherts that have been well developed. Enrichment of Selenium in Se-rich ores is obviously controlled by stratigraphic position and lithological character. The closer the rocks are to the Maokou Formation cherts, the more they contain Selenium, but in case the stratigraphic horizons are close to one another, the enrichment of Selenium would be controlled by lithological character. In the Se ores and abandoned stone coal pile at the Yutangba Se deposit there have been found large amounts of independent Se Minerals, for instance, achavalite and a variety of forms of native Selenium. Native Selenium Minerals present in the abandoned stone coal pile are the outcome of a combination of natural factors and anthropologie activities. For example, lime making will create a closed environment favoring the growth of native Selenium, and the reduction of Selenium will lead to its secondary enrichment. Starting with the study of ore-forming fluids. Systematic studies have been conducted on fluid inclusions separated from the main ore veins in the mining district for their homogenization temperatures, salinities and density, and the results show that fluid inclusions contained in ores from the Yutangba Se deposit are large in number and diverse in form, dominated by primary ones. The homogenization temperatures of two types of fluid inclusions are within the range of 173.2–247.5°C, individually up to 300°C or even higher; the salinities of fluids in fluid inclusions in quartz and calcite are 5.9%–10.1% and 3.9%–4.5%, respectively; their densities vary from 0.79–0.93 g/cm3. Extensive discovery of Se Minerals due to secondary enrichment of Selenium in the stone coal provides important clues to the improvements on the metallurgical and recovery technologies for Selenium in the black shale series of China, and also is of great significance in expanding Selenium reserves and relax the situation of lacking Selenium resources on a global scale.
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Au-Se Paragenesis in Cambrian Stratabound Gold Deposits, Western Qinling Mountains, China
International Geology Review, 2000Co-Authors: Liu Jiajun, Liu Jianming, Zheng Minghua, Liu XianfanAbstract:Cambrian stratabound gold deposits in the western Qinling Mountains are hosted in a siliceous formation composed of black chert and carbonaceous slate. Studies have shown that Se is sufficiently high in abundance either in wall rocks or in gold ores as to reach economic grade. Locally, some independent Se ore bodies (Se >500 ppm) can be delineated. In gold ores, Se is present mainly as separate Minerals, or as isomorphous solutions in sulfides. In addition, Se is positively correlated with Au. What is more important is that in the gold ores, native gold is commonly intimately inter-grown with Selenium Minerals. On the basis of this unique phenomenon, the authors hypothesize that gold and Selenium may be transported by Au-S-Se or Au-Se complexes. The co-enrichment of Au and Se is attributed mainly to the boiling of ore fluids and their mixing with shallow-seated oxygen-bearing water.