Gold transport in hydrothermal fluids: Competition among the Cl-, Br-, HS- and NH3(aq) ligands
Since the Au(I) and Au(III) ions are not stable in water, gold transport and deposition in hydrothermal ore fluids are dependent on the identity and stability of the predominant aqueous gold complexes. Gold(I) bisulfide (e.g., Au(HS)2 -) and in some instances Au(I) chloride complexes are widely ackn...
| Main Authors: | , , , , , , |
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| Format: | Journal Article |
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Elsevier Science BV
2014
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| Online Access: | http://hdl.handle.net/20.500.11937/10611 |
| _version_ | 1848747581221371904 |
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| author | Liu, W. Etschmann, B. Testemale, D. Hazemann, J. Rempel, Kirsten Müller, H. Brugger, J. |
| author_facet | Liu, W. Etschmann, B. Testemale, D. Hazemann, J. Rempel, Kirsten Müller, H. Brugger, J. |
| author_sort | Liu, W. |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | Since the Au(I) and Au(III) ions are not stable in water, gold transport and deposition in hydrothermal ore fluids are dependent on the identity and stability of the predominant aqueous gold complexes. Gold(I) bisulfide (e.g., Au(HS)2 -) and in some instances Au(I) chloride complexes are widely acknowledged to account for gold transport in hydrothermal ore fluids. This study investigates the potential of the unconventional ligands Br- and NH3(aq) to increase gold mobility. This was achieved by determining the predominant gold species in hydrothermal fluids with binary mixed ligands (Br-–Cl-, Br-–HS-, HS-–NH3), and measuring their structural properties using in situ synchrotron X-ray absorption spectroscopy (XAS). The capacity of XAS to follow the progress of ligand exchange reactions was demonstrated using Au(III) at room temperature: the Au(III)Br4 - complex was found to predominate in mixed Br-–Cl- solutions (Br-/Cl- = 0.2–1), with average ligand numbers derived from XAS data in good agreement with the UV–vis study of Usher et al. (Geochim. Cosmochim. Acta 73, 3359–3380, 2009). At elevated temperatures up to 400 °C at 600 bar, the XA measurements show that Au(I)–HS- complexes are the only stable gold species in mixed HS-–Br- and HS-–NH3 fluids (HS-/Br-=0.1;HS-/NH3 = 0.2), suggesting that hydrosulfide is the most important ligand for gold transport in the hydrothermalfluid under our experimental conditions, i.e., hydrosulfide complexes outcompete bromide, chloride and ammine complexes in S-bearing fluids. |
| first_indexed | 2025-11-14T06:51:25Z |
| format | Journal Article |
| id | curtin-20.500.11937-10611 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T06:51:25Z |
| publishDate | 2014 |
| publisher | Elsevier Science BV |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-106112017-09-13T16:06:10Z Gold transport in hydrothermal fluids: Competition among the Cl-, Br-, HS- and NH3(aq) ligands Liu, W. Etschmann, B. Testemale, D. Hazemann, J. Rempel, Kirsten Müller, H. Brugger, J. Gold bromide and ammine complexes Synchrotron experiments XAS and XANES Gold transport in hydrothermal fluids Gold hydrosulfide complexes EXAFS Since the Au(I) and Au(III) ions are not stable in water, gold transport and deposition in hydrothermal ore fluids are dependent on the identity and stability of the predominant aqueous gold complexes. Gold(I) bisulfide (e.g., Au(HS)2 -) and in some instances Au(I) chloride complexes are widely acknowledged to account for gold transport in hydrothermal ore fluids. This study investigates the potential of the unconventional ligands Br- and NH3(aq) to increase gold mobility. This was achieved by determining the predominant gold species in hydrothermal fluids with binary mixed ligands (Br-–Cl-, Br-–HS-, HS-–NH3), and measuring their structural properties using in situ synchrotron X-ray absorption spectroscopy (XAS). The capacity of XAS to follow the progress of ligand exchange reactions was demonstrated using Au(III) at room temperature: the Au(III)Br4 - complex was found to predominate in mixed Br-–Cl- solutions (Br-/Cl- = 0.2–1), with average ligand numbers derived from XAS data in good agreement with the UV–vis study of Usher et al. (Geochim. Cosmochim. Acta 73, 3359–3380, 2009). At elevated temperatures up to 400 °C at 600 bar, the XA measurements show that Au(I)–HS- complexes are the only stable gold species in mixed HS-–Br- and HS-–NH3 fluids (HS-/Br-=0.1;HS-/NH3 = 0.2), suggesting that hydrosulfide is the most important ligand for gold transport in the hydrothermalfluid under our experimental conditions, i.e., hydrosulfide complexes outcompete bromide, chloride and ammine complexes in S-bearing fluids. 2014 Journal Article http://hdl.handle.net/20.500.11937/10611 10.1016/j.chemgeo.2014.03.012 Elsevier Science BV restricted |
| spellingShingle | Gold bromide and ammine complexes Synchrotron experiments XAS and XANES Gold transport in hydrothermal fluids Gold hydrosulfide complexes EXAFS Liu, W. Etschmann, B. Testemale, D. Hazemann, J. Rempel, Kirsten Müller, H. Brugger, J. Gold transport in hydrothermal fluids: Competition among the Cl-, Br-, HS- and NH3(aq) ligands |
| title | Gold transport in hydrothermal fluids: Competition among the Cl-, Br-, HS- and NH3(aq) ligands |
| title_full | Gold transport in hydrothermal fluids: Competition among the Cl-, Br-, HS- and NH3(aq) ligands |
| title_fullStr | Gold transport in hydrothermal fluids: Competition among the Cl-, Br-, HS- and NH3(aq) ligands |
| title_full_unstemmed | Gold transport in hydrothermal fluids: Competition among the Cl-, Br-, HS- and NH3(aq) ligands |
| title_short | Gold transport in hydrothermal fluids: Competition among the Cl-, Br-, HS- and NH3(aq) ligands |
| title_sort | gold transport in hydrothermal fluids: competition among the cl-, br-, hs- and nh3(aq) ligands |
| topic | Gold bromide and ammine complexes Synchrotron experiments XAS and XANES Gold transport in hydrothermal fluids Gold hydrosulfide complexes EXAFS |
| url | http://hdl.handle.net/20.500.11937/10611 |