Skip to main content
Article
Licensed
Unlicensed Requires Authentication

Chemical speciation of Ag in galena by EPR spectroscopy

  • , EMAIL logo , , , , and
Published/Copyright: March 31, 2015
Become an author with De Gruyter Brill
Author Information
American Mineralogist
From the journal American Mineralogist Volume 88 Issue 8-9

Abstract

Electron paramagnetic resonance (EPR) spectroscopy has been used to study the valence state of silver in “argentiferous” galena samples from the Apuane Alps (Tuscany, Italy) mining district. This method was used to reveal primary metallic silver (Ag0) in galena. Both thermodynamic data and experimental studies suggest that galena and native silver can stably coexist, but have not been reported as a primary (hypogene) assemblage in natural samples. EPR spectroscopy proved to be a suitable tool to solve this problem, because this technique is capable of detecting paramagnetic species down to the ppb level, even in a highly absorbent matrix such as galena.

A detailed SEM-EDS investigation could not detect metallic silver (or gold) in galena samples, but did reveal small (few micrometers) inclusions of Ag-bearing phases, in which silver has a formal valence of +1. On the other hand, EPR spectra indicated the presence in galena of pairs and clusters of elemental silver atoms, which may be associated with pairs of metallic gold, or with silver-gold hetero-atomic pairs. Therefore, SEM/EDS and EPR are complementary techniques, revealing the presence of both Ag+ and Ag0.

The Ag(Au) metallic species were apparently deposited on the galena surface during its growth from mineralizing fluids. Their scarcity, and the presence of larger amounts of Ag1+ phases, suggest that the assemblage galena-metallic silver was stable only under peculiar physical and chemical conditions. The formation of Ag0 was presumably linked to local and rare chemical fluctuations of the hydrothermal environment, characterized by low activities of S, Sb, Bi (Cu…) and high activity of Ag in the fluids. The occurrence of both homo- and hetero-atomic pairs suggests either different kinetics of pair formation, or possible fluctuations in the composition of the hydrothermal fluids, which alternatively carried Ag or Au species, or both

Received: 2002-10-3
Accepted: 2003-3-25
Published Online: 2015-3-31
Published in Print: 2003-8-1

© 2015 by Walter de Gruyter Berlin/Boston

Articles in the same Issue

  1. Melting of garnet peridotite: Effects of capsules and thermocouples, and implications for the high-pressure mantle solidus
  2. High-resolution and energy-filtered TEM of the interface between hematite and ilmenite exsolution lamellae: Relevance to the origin of lamellar magnetism
  3. The structural evolution of mercury sulfide precipitate: an XAS and XRD study
  4. Synthetic fluid inclusions as recorders of microfracture healing and overgrowth formation rates
  5. Fluid-induced nucleation of (Y+REE)-phosphate minerals within apatite: Nature and experiment. Part II. Fluorapatite
  6. A technique for measuring 3D crystal-size distributions of prismatic microlites in obsidian
  7. TEM investigation of forsterite dendrites
  8. Mechanism and kinetics of element and isotopic exchange mediated by a fluid phase
  9. Chromian spinel during melting experiments of dry peridotite (KLB-1) at 1.0–2.5 GPa
  10. Resonant XPS study of the pyrite valence band with implications for molecular orbital contributions
  11. Petrology and mineralogy of wollastonite- and melilite-bearing paralavas from the Central Apennines, Italy
  12. Variation of antiphase domain size in omphacite: A tool to determine the temperature–time history of eclogites revisited
  13. Compressional and shear wave velocities of ringwoodite γ-Mg2SiO4 to 12 GPa
  14. A vibrational spectroscopic study of the oxidation of pyrite by ferric iron
  15. The atomic arrangement of the ganophyllite-group modulated layer silicates as determined from the orthorhombic dimorph of tamaite, with the elusive 16.8 Å ganophyllite-group superstructure revealed
  16. The crystal structure of chromian kassite from the Saranovskoye deposit, Northern Urals, Russia
  17. Spectroscopic and related evidence on the coloring and constitution of New Zealand jade
  18. Chemical speciation of Ag in galena by EPR spectroscopy
  19. Pressure dependence of melt viscosity in the system NaAlSi3O8-CaMgSi2O6
  20. Molecules in the SiO2-clathrate melanophlogite: A single-crystal Raman study
  21. Mn-rich tourmaline from Austria: structure, chemistry, optical spectra, and relations to synthetic solid solutions
  22. Compositional heterogeneity of olivine in thermally metamorphosed serpentinite from Southwest Japan
  23. Magnetic monitoring of hydrothermal magnetite nucleation-and-growth: Record of magnetic reversals
  24. High-temperature limits on viscosity of non-Arrhenian silicate melts
  25. First reported sedimentary occurrence of berlinite (AlPO4) in phosphate-bearing sediments from Cioclovina Cave, Romania
https://doi.org/10.2138/am-2003-8-918

Articles in the same Issue

  1. Melting of garnet peridotite: Effects of capsules and thermocouples, and implications for the high-pressure mantle solidus
  2. High-resolution and energy-filtered TEM of the interface between hematite and ilmenite exsolution lamellae: Relevance to the origin of lamellar magnetism
  3. The structural evolution of mercury sulfide precipitate: an XAS and XRD study
  4. Synthetic fluid inclusions as recorders of microfracture healing and overgrowth formation rates
  5. Fluid-induced nucleation of (Y+REE)-phosphate minerals within apatite: Nature and experiment. Part II. Fluorapatite
  6. A technique for measuring 3D crystal-size distributions of prismatic microlites in obsidian
  7. TEM investigation of forsterite dendrites
  8. Mechanism and kinetics of element and isotopic exchange mediated by a fluid phase
  9. Chromian spinel during melting experiments of dry peridotite (KLB-1) at 1.0–2.5 GPa
  10. Resonant XPS study of the pyrite valence band with implications for molecular orbital contributions
  11. Petrology and mineralogy of wollastonite- and melilite-bearing paralavas from the Central Apennines, Italy
  12. Variation of antiphase domain size in omphacite: A tool to determine the temperature–time history of eclogites revisited
  13. Compressional and shear wave velocities of ringwoodite γ-Mg2SiO4 to 12 GPa
  14. A vibrational spectroscopic study of the oxidation of pyrite by ferric iron
  15. The atomic arrangement of the ganophyllite-group modulated layer silicates as determined from the orthorhombic dimorph of tamaite, with the elusive 16.8 Å ganophyllite-group superstructure revealed
  16. The crystal structure of chromian kassite from the Saranovskoye deposit, Northern Urals, Russia
  17. Spectroscopic and related evidence on the coloring and constitution of New Zealand jade
  18. Chemical speciation of Ag in galena by EPR spectroscopy
  19. Pressure dependence of melt viscosity in the system NaAlSi3O8-CaMgSi2O6
  20. Molecules in the SiO2-clathrate melanophlogite: A single-crystal Raman study
  21. Mn-rich tourmaline from Austria: structure, chemistry, optical spectra, and relations to synthetic solid solutions
  22. Compositional heterogeneity of olivine in thermally metamorphosed serpentinite from Southwest Japan
  23. Magnetic monitoring of hydrothermal magnetite nucleation-and-growth: Record of magnetic reversals
  24. High-temperature limits on viscosity of non-Arrhenian silicate melts
  25. First reported sedimentary occurrence of berlinite (AlPO4) in phosphate-bearing sediments from Cioclovina Cave, Romania
Downloaded on 16.4.2026 from https://www.degruyterbrill.com/document/doi/10.2138/am-2003-8-918/html
Scroll to top button