Home Mechanism of mineral transformations in krennerite, Au3AgTe8, under hydrothermal conditions
Article
Licensed
Unlicensed Requires Authentication

Mechanism of mineral transformations in krennerite, Au3AgTe8, under hydrothermal conditions

  • Weina Xu , Jing Zhao , Joël Brugger , Guorong Chen and Allan Pring EMAIL logo
Published/Copyright: March 7, 2015
Become an author with De Gruyter Brill
Author Information
American Mineralogist
From the journal American Mineralogist Volume 98 Issue 11-12

Abstract

Calaverite, krennerite, and sylvanite are Au-Ag-tellurides with close compositions and related crystal structures. Previous experimental studies show that both calaverite and sylvanite transform to porous “mustard” gold under hydrothermal conditions; however the transformation of sylvanite follows a complex reaction path with several intermediary products, contrasting with the simple replacement of calaverite by gold. Here we report results of an experimental study of the transformation of krennerite, a phase with Ag contents intermediate between those of calaverite and sylvanite.

Krennerite was replaced by Au-Ag alloy under all experimental conditions explored (160 to 220 °C; pHT ~ 3 and 9; varying availability of oxygen). No reaction was observed at the same temperature under dry conditions. The replacement was pseudomorphic and the resulting Au-Ag alloy was porous, consisting of worm-like aggregates with diameters ranging from 200 nm to 1 μm. The replacement of krennerite proceeds via an interface coupled dissolution-(re)precipitation (ICDR) reaction mechanism. Tellurium is lost to the bulk solution as Te(IV) complexes, and may precipitate away from the dissolution site. In contrast, Au-Ag alloy precipitates locally near the krennerite dissolution site. Overall, the hydrothermal alteration of krennerite is very similar to that of calaverite, but differs from the alteration of sylvanite, for which multi-step reaction paths led to complex products and textures under similar conditions. These striking differences are driven by the competition between solid-state reactions and ICDR reaction in sylvanite. This reflects the fact that a metastable, Ag-rich calaverite nucleates on sylvanite during the early steps of its dissolution, as a result of the close relationship between the structures of these two minerals and the enrichment in Au, Ag, and Te in solution at the reaction front. In contrast, for calaverite and krennerite, no such phase precipitates, and both minerals are transformed in a pseudomorphic manner into Au-Ag alloy.

Keywords : Krennerite; gold; dissolution-reprecipitation; pseudomorphism; replacement
Received: 2013-1-28
Accepted: 2013-7-1
Published Online: 2015-3-7
Published in Print: 2013-11-1

© 2015 by Walter de Gruyter Berlin/Boston

Articles in the same Issue

  1. Highlights and Breakthroughs. Lessons from a lost technology: The secrets of Roman concrete
  2. Crossroads in Earth and Planetary Materials. H-D interdiffusion in brucite at pressures up to 15 GPa
  3. Amorphous Materials: Properties, structure, and durability. North American microtektites are more oxidized than tektites
  4. Actinides in Geology, Energy, and the Environment. Vorlanite, (CaU6+)O4, from Jabel Harmun, Palestinian Autonomy, Israel
  5. What Lurks in the Martian Rocks and Soil? Investigations of Sulfates, Phosphates, and Perchlorates. Mössbauer parameters of iron in sulfate minerals
  6. What Lurks in the Martian Rocks and Soil? Investigations of Sulfates, Phosphates, and Perchlorates. Looking for jarosite on Mars: The low-temperature crystal structure of jarosite
  7. Compressibility and structural stability of two variably hydrated olivine samples. (FO97Fa3) to 34 GPa by X-ray diffraction and Raman spectroscopy
  8. Interaction between composition and temperature effects on non-bridging oxygen and high-coordinated aluminum in calcium aluminosilicate glasses
  9. Topotactic transformation and dehydration of the zeolite gismondine to a novel Ca feldspar structure
  10. The origin of melanophlogite, a clathrate mineral, in natrocarbonatite lava at Oldoinyo Lengai, Tanzania
  11. Clay mineral evolution
  12. Experimental determination of solubilities of sodium tetraborate (borax) in NaCl solutions, and a thermodynamic model for the Na-B(OH)3-Cl-SO4 system to high-ionic strengths at 25 °C
  13. Thermodynamic basis for evolution of apatite in calcified tissues
  14. A first-principles calculation of the elastic and vibrational anomalies of lizardite under pressure
  15. Acoustic velocity measurements for stishovite across the post-stishovite phase transition under deviatoric stress: Implications for the seismic features of subducting slabs in the mid-mantle
  16. A new framework topology in the dehydrated form of zeolite levyne
  17. Mid- and far-infrared spectra of synthetic CaMg2(Al4–xGax)(Si1–yGey)O10(OH,OD)2- clintonite: Characterization and assignment of the Ca-Oinner and Ca-Oouter stretching bands
  18. Mechanism of mineral transformations in krennerite, Au3AgTe8, under hydrothermal conditions
  19. Cubic perovskite polymorph of strontium metasilicate at high pressures
  20. Size distributions of nanoparticles from magnetotactic bacteria as signatures of biologically controlled mineralization
  21. Medium-range order in disordered K-feldspars by multinuclear NMR
  22. Infrared signatures of OH-defects in wadsleyite: A first-principles study
  23. K-Ar dating and δ18O-δD characterization of nanometric illite from Ordovician. K-bentonites of the Appalachians: Illitization and the Acadian-Alleghenian tectonic activity
  24. New morphological, chemical, and structural data of woolly erionite-Na from Durkee, Oregon, U.S.A.
  25. New experimental data on phase relations for the system Na2CO3-CaCO3 at 6 GPa and 900–1400 ºC
  26. Melting and subsolidus phase relations in the system Na2CO3-MgCO3±H2O at 6 GPa and the stability of Na2Mg(CO3)2 in the upper mantle
  27. A critical comment on Ertl et al. (2012): “Limitations of Fe2+ and Mn2+ site occupancy in tourmaline: Evidence from Fe2+- and Mn2+-rich tourmaline”
  28. Letter. Developing vanadium valence state oxybarometers (spinel-melt, olivine-melt, spinel-olivine) and V/(Cr+Al) partitioning (spinel-melt) for martian olivine-phyric basalts
https://doi.org/10.2138/am.2013.4485
Keywords for this article
Krennerite; gold; dissolution-reprecipitation; pseudomorphism; replacement

Articles in the same Issue

  1. Highlights and Breakthroughs. Lessons from a lost technology: The secrets of Roman concrete
  2. Crossroads in Earth and Planetary Materials. H-D interdiffusion in brucite at pressures up to 15 GPa
  3. Amorphous Materials: Properties, structure, and durability. North American microtektites are more oxidized than tektites
  4. Actinides in Geology, Energy, and the Environment. Vorlanite, (CaU6+)O4, from Jabel Harmun, Palestinian Autonomy, Israel
  5. What Lurks in the Martian Rocks and Soil? Investigations of Sulfates, Phosphates, and Perchlorates. Mössbauer parameters of iron in sulfate minerals
  6. What Lurks in the Martian Rocks and Soil? Investigations of Sulfates, Phosphates, and Perchlorates. Looking for jarosite on Mars: The low-temperature crystal structure of jarosite
  7. Compressibility and structural stability of two variably hydrated olivine samples. (FO97Fa3) to 34 GPa by X-ray diffraction and Raman spectroscopy
  8. Interaction between composition and temperature effects on non-bridging oxygen and high-coordinated aluminum in calcium aluminosilicate glasses
  9. Topotactic transformation and dehydration of the zeolite gismondine to a novel Ca feldspar structure
  10. The origin of melanophlogite, a clathrate mineral, in natrocarbonatite lava at Oldoinyo Lengai, Tanzania
  11. Clay mineral evolution
  12. Experimental determination of solubilities of sodium tetraborate (borax) in NaCl solutions, and a thermodynamic model for the Na-B(OH)3-Cl-SO4 system to high-ionic strengths at 25 °C
  13. Thermodynamic basis for evolution of apatite in calcified tissues
  14. A first-principles calculation of the elastic and vibrational anomalies of lizardite under pressure
  15. Acoustic velocity measurements for stishovite across the post-stishovite phase transition under deviatoric stress: Implications for the seismic features of subducting slabs in the mid-mantle
  16. A new framework topology in the dehydrated form of zeolite levyne
  17. Mid- and far-infrared spectra of synthetic CaMg2(Al4–xGax)(Si1–yGey)O10(OH,OD)2- clintonite: Characterization and assignment of the Ca-Oinner and Ca-Oouter stretching bands
  18. Mechanism of mineral transformations in krennerite, Au3AgTe8, under hydrothermal conditions
  19. Cubic perovskite polymorph of strontium metasilicate at high pressures
  20. Size distributions of nanoparticles from magnetotactic bacteria as signatures of biologically controlled mineralization
  21. Medium-range order in disordered K-feldspars by multinuclear NMR
  22. Infrared signatures of OH-defects in wadsleyite: A first-principles study
  23. K-Ar dating and δ18O-δD characterization of nanometric illite from Ordovician. K-bentonites of the Appalachians: Illitization and the Acadian-Alleghenian tectonic activity
  24. New morphological, chemical, and structural data of woolly erionite-Na from Durkee, Oregon, U.S.A.
  25. New experimental data on phase relations for the system Na2CO3-CaCO3 at 6 GPa and 900–1400 ºC
  26. Melting and subsolidus phase relations in the system Na2CO3-MgCO3±H2O at 6 GPa and the stability of Na2Mg(CO3)2 in the upper mantle
  27. A critical comment on Ertl et al. (2012): “Limitations of Fe2+ and Mn2+ site occupancy in tourmaline: Evidence from Fe2+- and Mn2+-rich tourmaline”
  28. Letter. Developing vanadium valence state oxybarometers (spinel-melt, olivine-melt, spinel-olivine) and V/(Cr+Al) partitioning (spinel-melt) for martian olivine-phyric basalts
Sign up now to receive a 20% welcome discount
Institutional Access
How does access work?
Have an idea on how to improve our website?
Please write us.
© 2025 De Gruyter Brill
Downloaded on 17.9.2025 from https://www.degruyterbrill.com/document/doi/10.2138/am.2013.4485/html
Scroll to top button