Speciation of aqueous tellurium(IV) in hydrothermal solutions and vapors, and the role of oxidized tellurium species in Te transport and gold deposition.
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| Title: | Speciation of aqueous tellurium(IV) in hydrothermal solutions and vapors, and the role of oxidized tellurium species in Te transport and gold deposition. |
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| Authors: | Grundler, Pascal V.1,2, Brugger, Joël1,2 joel.brugger@adelaide.edu.au, Etschmann, Barbara E.1,2, Helm, Lothar3, Liu, Weihua4, Spry, Paul G.5, Tian, Yuan2,6, Testemale, Denis7, Pring, Allan1,2 allan.pring@samuseum.sa.gov.au |
| Source: | Geochimica et Cosmochimica Acta. Nov2013, Vol. 120, p298-325. 28p. |
| Subjects: | Chemical speciation, Tellurium, Ore deposits, Proton transfer reactions, Aqueous solutions, Hydrogen-ion concentration, Thermodynamics |
| Abstract: | Despite the close association between tellurium (Te) and gold (Au) in many epithermal, orogenic, and intrusion-related hydrothermal ore deposits, the hydrothermal chemistry of Te remains poorly understood. We studied the protonation/deprotonation and structure of tellurous acid (H2TeIVO3) species in aqueous solutions and in water vapor as a function of pH from room-temperature to 505°C using a number of methods: TeO2(s) solubility in solution and steam, potentiometry, NMR spectroscopy, and in situ XAS spectroscopy. The solubility of TeO2(s) increases by up to a factor 80 between ambient temperature and 200°C. As the temperature increases, the pH range over which the neutral species H2TeO3(aq) dominates to the detriment of the ionic species , and expands. The structure of these species is a trigonal pyramid with the Te atom at its apex, indicating a stereochemically active electron pair. The Te–O bond lengths increase with increasing protonation (i.e., decreasing pH). Although hydrated tellurite species such as TeO2(H2O)(g) and TeO2(H2O)2(g) exist in significant concentrations in vapors equilibrated with TeO2(s), these species are unlikely to play a significant role in natural systems, because of the high solubility of Te(IV) in the liquid phase under these conditions. Solubility calculations conducted with the new and existing properties confirm the importance of reduced species for the vapor transport of Te, with a partitioning coefficient (Kd =Te concentration in vapor/Te concentration in liquid) up to >105 in favor of the vapor, and ppm concentrations of Te in reduced vapors at 300°C. Thermodynamic calculations show that slightly basic, mildly reduced fluids that can transport Au efficiently as can also carry significant Te (e.g., ∼100ppb at 300°C). The calculations also suggest that under magmatic hydrothermal conditions, large amounts of Te can be transported as Te(IV) complexes in oxidized fluids (coexisting with SO2(g)). Reduction of Te(IV) caused by processes such as fluid–rock interaction or fluid mixing will lead to a dramatic decrease in the solubilities of both Te and Au, and to the precipitation of telluride minerals. [ABSTRACT FROM AUTHOR] |
| Copyright of Geochimica et Cosmochimica Acta is the property of Pergamon Press - An Imprint of Elsevier Science and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) | |
| Database: | Engineering Source |
| FullText | Text: Availability: 0 |
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| Header | DbId: egs DbLabel: Engineering Source An: 90312863 AccessLevel: 6 PubType: Academic Journal PubTypeId: academicJournal PreciseRelevancyScore: 0 |
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| Items | – Name: Title Label: Title Group: Ti Data: Speciation of aqueous tellurium(IV) in hydrothermal solutions and vapors, and the role of oxidized tellurium species in Te transport and gold deposition. – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Grundler%2C+Pascal+V%2E%22">Grundler, Pascal V.</searchLink><relatesTo>1,2</relatesTo><br /><searchLink fieldCode="AR" term="%22Brugger%2C+Joël%22">Brugger, Joël</searchLink><relatesTo>1,2</relatesTo><i> joel.brugger@adelaide.edu.au</i><br /><searchLink fieldCode="AR" term="%22Etschmann%2C+Barbara+E%2E%22">Etschmann, Barbara E.</searchLink><relatesTo>1,2</relatesTo><br /><searchLink fieldCode="AR" term="%22Helm%2C+Lothar%22">Helm, Lothar</searchLink><relatesTo>3</relatesTo><br /><searchLink fieldCode="AR" term="%22Liu%2C+Weihua%22">Liu, Weihua</searchLink><relatesTo>4</relatesTo><br /><searchLink fieldCode="AR" term="%22Spry%2C+Paul+G%2E%22">Spry, Paul G.</searchLink><relatesTo>5</relatesTo><br /><searchLink fieldCode="AR" term="%22Tian%2C+Yuan%22">Tian, Yuan</searchLink><relatesTo>2,6</relatesTo><br /><searchLink fieldCode="AR" term="%22Testemale%2C+Denis%22">Testemale, Denis</searchLink><relatesTo>7</relatesTo><br /><searchLink fieldCode="AR" term="%22Pring%2C+Allan%22">Pring, Allan</searchLink><relatesTo>1,2</relatesTo><i> allan.pring@samuseum.sa.gov.au</i> – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22Geochimica+et+Cosmochimica+Acta%22">Geochimica et Cosmochimica Acta</searchLink>. Nov2013, Vol. 120, p298-325. 28p. – Name: Subject Label: Subjects Group: Su Data: <searchLink fieldCode="DE" term="%22Chemical+speciation%22">Chemical speciation</searchLink><br /><searchLink fieldCode="DE" term="%22Tellurium%22">Tellurium</searchLink><br /><searchLink fieldCode="DE" term="%22Ore+deposits%22">Ore deposits</searchLink><br /><searchLink fieldCode="DE" term="%22Proton+transfer+reactions%22">Proton transfer reactions</searchLink><br /><searchLink fieldCode="DE" term="%22Aqueous+solutions%22">Aqueous solutions</searchLink><br /><searchLink fieldCode="DE" term="%22Hydrogen-ion+concentration%22">Hydrogen-ion concentration</searchLink><br /><searchLink fieldCode="DE" term="%22Thermodynamics%22">Thermodynamics</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: Despite the close association between tellurium (Te) and gold (Au) in many epithermal, orogenic, and intrusion-related hydrothermal ore deposits, the hydrothermal chemistry of Te remains poorly understood. We studied the protonation/deprotonation and structure of tellurous acid (H2TeIVO3) species in aqueous solutions and in water vapor as a function of pH from room-temperature to 505°C using a number of methods: TeO2(s) solubility in solution and steam, potentiometry, NMR spectroscopy, and in situ XAS spectroscopy. The solubility of TeO2(s) increases by up to a factor 80 between ambient temperature and 200°C. As the temperature increases, the pH range over which the neutral species H2TeO3(aq) dominates to the detriment of the ionic species , and expands. The structure of these species is a trigonal pyramid with the Te atom at its apex, indicating a stereochemically active electron pair. The Te–O bond lengths increase with increasing protonation (i.e., decreasing pH). Although hydrated tellurite species such as TeO2(H2O)(g) and TeO2(H2O)2(g) exist in significant concentrations in vapors equilibrated with TeO2(s), these species are unlikely to play a significant role in natural systems, because of the high solubility of Te(IV) in the liquid phase under these conditions. Solubility calculations conducted with the new and existing properties confirm the importance of reduced species for the vapor transport of Te, with a partitioning coefficient (Kd =Te concentration in vapor/Te concentration in liquid) up to >105 in favor of the vapor, and ppm concentrations of Te in reduced vapors at 300°C. Thermodynamic calculations show that slightly basic, mildly reduced fluids that can transport Au efficiently as can also carry significant Te (e.g., ∼100ppb at 300°C). The calculations also suggest that under magmatic hydrothermal conditions, large amounts of Te can be transported as Te(IV) complexes in oxidized fluids (coexisting with SO2(g)). Reduction of Te(IV) caused by processes such as fluid–rock interaction or fluid mixing will lead to a dramatic decrease in the solubilities of both Te and Au, and to the precipitation of telluride minerals. [ABSTRACT FROM AUTHOR] – Name: AbstractSuppliedCopyright Label: Group: Ab Data: <i>Copyright of Geochimica et Cosmochimica Acta is the property of Pergamon Press - An Imprint of Elsevier Science and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.) |
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| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.1016/j.gca.2013.06.009 Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 28 StartPage: 298 Subjects: – SubjectFull: Chemical speciation Type: general – SubjectFull: Tellurium Type: general – SubjectFull: Ore deposits Type: general – SubjectFull: Proton transfer reactions Type: general – SubjectFull: Aqueous solutions Type: general – SubjectFull: Hydrogen-ion concentration Type: general – SubjectFull: Thermodynamics Type: general Titles: – TitleFull: Speciation of aqueous tellurium(IV) in hydrothermal solutions and vapors, and the role of oxidized tellurium species in Te transport and gold deposition. Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Grundler, Pascal V. – PersonEntity: Name: NameFull: Brugger, Joël – PersonEntity: Name: NameFull: Etschmann, Barbara E. – PersonEntity: Name: NameFull: Helm, Lothar – PersonEntity: Name: NameFull: Liu, Weihua – PersonEntity: Name: NameFull: Spry, Paul G. – PersonEntity: Name: NameFull: Tian, Yuan – PersonEntity: Name: NameFull: Testemale, Denis – PersonEntity: Name: NameFull: Pring, Allan IsPartOfRelationships: – BibEntity: Dates: – D: 01 M: 11 Text: Nov2013 Type: published Y: 2013 Identifiers: – Type: issn-print Value: 00167037 Numbering: – Type: volume Value: 120 Titles: – TitleFull: Geochimica et Cosmochimica Acta Type: main |
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