Advertisement

Physics and Chemistry of Minerals

, Volume 11, Issue 1, pp 37–51 | Cite as

Mixed valence of iron in minerals with cation clusters

  • Georg Amthauer
  • George R. Rossman
Article

Abstract

The valence and distribution of iron in vivianite, lazulite, babingtonite, rockbridgeite, acmite, aegirine-augite, hedenbergite, and ilvaite were studied with optical and Mössbauer spectroscopy. Optically activated intervalence charge transfer between Fe2+ and Fe3+ in neighboring sites through common edges or faces is observed in all these minerals irrespective of the polymerization of the iron-oxygen polyhedra ranging from finite clusters to infinite structural units. However, a distinct decrease occurs in the energy of the corresponding optical absorption band with increasing number of Fe2+ and Fe3+ ions involved in the charge transfer process. Thermally activated electron delocalization between Fe2+ and Fe3+ occurs only if Fe2+ and Fe3+ occupy crystallographically equivalent or geometrically very similar neighboring sites which share common edges to form extended structural units such as the ribbon in ilvaite. If the Fe-O polyhedra form finite clusters of two, three, or four polyhedra (e.g., in vivianite, lazulite, and babingtonite, respectively) no thermally-activated mixed-valence states of iron are observed. In aegirine, extended regions of the M1 chain are statistically occupied by Fe2+ and Fe3+ giving rise to thermally-activated electron delocalization in addition to the intervalence band in the optical absorption spectrum. The intensity of the optical intervalence absorption has been measured in a number of systems: ɛ values range from 60 to 210.

Keywords

Optical Absorption Structural Unit Optical Absorption Spectrum Electron Delocalization Charge Transfer Process 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Amthauer G (1980) 57Fe Mössbauer study of babingtonite. Am Mineral 65:157–162Google Scholar
  2. Amthauer G, Evans BJ (1978) Single crystal and high pressure 57Fe Mössbauer studies of ilvaite, CaFe22+ Fe3+ (Si2O7/O/OH) at 298 K. Phys Chem Minerals 3:55–56Google Scholar
  3. Amthauer G, Annersten H, Hafner SS (1976) The Mössbauer spectrum of 57Fe in silicate garnets. Z Kristallogr 143:14–55Google Scholar
  4. Amthauer G, Langer K, Schliestedt M (1980) Thermally activated electron delocalization in deerite. Phys Chem Minerals 6:19–30Google Scholar
  5. Annersten H, Nyambok IO (1978) Iron distribution in aegirineaugite clinopyroxenes studied by Mössbauer effect. UUDMP Research Report No. 11, UppsalaGoogle Scholar
  6. Araki T, Zoltai T (1972) Crystal structure of babingtonite. Z Kristallogr 135:355–373Google Scholar
  7. Austin IG, Mott NF (1970) Metallic and nonmetallic behaviour in transition metal oxides. Science 168:71–77Google Scholar
  8. Bauminger R, Cohen SG, Marinov A, Ofer S, Segal E (1961) Study of the low-temperature transition in magnetite and the internal fields acting on iron nuclei in some spinel ferrites using Mössbauer absorption. Phys Rev 122:1447–1450Google Scholar
  9. Belov NV, Mokeeva VI (1954) The crystal structure of ilvaite. Trudy Inst Kristallogr Akad Nauk SSSR 9:89–102Google Scholar
  10. Bence AE, Albee AL (1968) Empirical correction factors for the electron microanalysis of silicates and oxides. J Geol 76:382–403Google Scholar
  11. Beran A, Bittner H (1974) Untersuchungen zur Kristallchemie des Ilvaits. Tschermaks Mineral Petrogr Mitt 21:11–29Google Scholar
  12. Beveridge D, Day P (1979) Charge transfer in mixed-valence solids. Part 9. Preparation, characterization, and optical spectroscopy of the mixed-valence minerale voltaite (aluminum pentairon(II) tri-iron(III) dipotassium dodecasulphate 18-hydrate) and its solid solutions with cadmium(II). J C S Dalton 648–653Google Scholar
  13. Burns RG (1970) Mineralogical applications of crystal field theory. Cambridge University Press, CambridgeGoogle Scholar
  14. Burns RG (1981) Intervalence transitions in mixed-valence minerals of iron and titanium. Ann Rev Earth Planet Sci 9:345–383Google Scholar
  15. Burns RG, Nolet DA, Parkin KM, McCammon CA, Schwartz KB (1979) Mixed-valence minerals of iron and titanium: correlations of structural, Mössbauer and electronic spectral data. In: Brown DB (ed) Mixed-Valence Compounds. D Reidel Publ Co, Dordrecht, pp 295–336Google Scholar
  16. Cameron M Papike JJ (1981) Structural and chemical variations in pyroxenes. Am Mineral 66:1–50Google Scholar
  17. Clark JR, Appleman DE, Papike JJ (1969) Crystal chemical characterization of clinopyroxenes based on eight new structure refinements. Mineral Soc Amer Special Paper 2:31–50Google Scholar
  18. Cox PA (1980) Electron transfer between exchange-coupled ions in a mixed-valency compound. Chem Phys Lett 69:340–343Google Scholar
  19. Dormann JL, Poullen JF (1980) Etude par spectroscopie Mössbauer de vivianites oxydees naturelles. Bull Minéral 103:633–639Google Scholar
  20. Dormann JL, Gaspérin M, Poullen JF (1982) Etude structurale de la séquence d'oxydation de la vivianite Fe3(PO4)2·8H2O. Bull Minéral 105:147–160Google Scholar
  21. Dowty E, Lindsley DH (1973) Mössbauer spectra of synthetic hedenbergite-ferrosilite pyroxenes. Am Mineral 58:850–868Google Scholar
  22. Evans BJ, Amthauer G (1980) The electronic structure of ilvaite and the pressure and temperature dependence of its 57Fe Mössbauer spectrum. J Phys Chem Solids 41:985–1001Google Scholar
  23. Faye GH (1968) The optical absorption spectra of iron in six-coordinate sites in chlorite, biotite, phlogopite and vivianite. Some aspects of pleochroism in the sheet silicates. Can Mineral 9:403–425Google Scholar
  24. Faye GH, Manning PG, Nickel EH (1968) The polarized optical absorption spectra of tourmaline, cordierite, chloritoid, and vivanite: ferrous-ferric electronic interaction as a source of pleochroism. Am Mineral 53:1174–1201Google Scholar
  25. Finger LW, Hazen KM, Hughes JM (1982) Crystal structure of monoclinic ilvaite. Carnegie Institution Year Book 81:386–388Google Scholar
  26. Fleet ME (1977) The crystal structure of deerite. Am Mineral 62:990–998Google Scholar
  27. Gerard A, Grandjean F (1971) Observations by the Mössbauer effect of an electron hopping process in ilvaite. Solid State Commun 9:1845–1849Google Scholar
  28. Goldman DS, Rossman GR (1977) The spectra of iron in orthopyroxene revisited: the splitting of the ground sate. Am Mineral 62:151–157Google Scholar
  29. Haga N, Takeuchi Y (1976) Neutron diffraction study of ilvaite. Z Kristallogr 144:161–174Google Scholar
  30. Hamilton WC (1958) Neutron diffraction investigation of the 119° K transition in magnetite. Phys Rev 110:1050–1057Google Scholar
  31. Herzenberg CL, Riley DL (1969) Oxidation states and site symmetries of iron in ilvaite using Mössbauer spectrometry. Acta Crystallogr A 25:389–391Google Scholar
  32. Hush NS (1967) Intervalence-transfer absorption. Part 2. Theoretical considerations and spectroscopic data. In: Prog Inorg Chem 8:391–612. Cotton FA (ed) John Wiley and Sons, New YorkGoogle Scholar
  33. Lindberg ML, Christ CL (1959) Crystal structure of the isostructural minerals lazulite, scorzalite, and barbosalite. Acta Crystallogr 12:695–697Google Scholar
  34. Litterst FJ, Amthauer G (1984) Electron delocalization in ilvaite, are reinterpretation of its 57Fe Mössbauer spectrum. Phys Chem Minerals 10:250–255Google Scholar
  35. Loeffler BM, Burns RG, Tossell JA (1975) Metal-metal charge transfer transitions: Interpretations of visible region spectra of the moon and lunar materials. Proc 6th Lunar Sci Conf 3:2663–2676Google Scholar
  36. Lotgering FK, van Diepen AM (1977) Electron exchange between Fe2+ and Fe3+ ions on octahedral sites in spinels studied by means of paramagnetic Mössbauer spectra and susceptibility measurements. J Phys Chem Solids 38:565–572Google Scholar
  37. McCammon CA, Burns RG (1980) The oxidation mechanism of vivianite as studied by Mössbauer spectroscopy. Am Mineral 65:361–366Google Scholar
  38. Moore PB (1970) Crystal chemistry of the basic iron phosphates. Am Mineral 55:135–169Google Scholar
  39. Mori H, Ito T (1950) The structure of vivianite and symplesite. Acta Crystallogr 3:1–6Google Scholar
  40. Mott NF (1980) Materials with mixed valency that show a Verwey transition. Phil Mag B42:327–335Google Scholar
  41. Nolet DA, Burns RG (1978) Temperature dependent Fe2+-Fe3+ electron delocalization in ilvaite. Geophys Res Lett 5:821–824Google Scholar
  42. Nolet DA, Burns RG (1979) Ilvaite: A study of temperature dependent electron delocalization by the Mössbauer effect. Phys Chem Minerals 4:221–234Google Scholar
  43. Pecora WT, Fahey JJ (1947) Scorzalite and souzalite, two new phosphate minerals associated with brazilianite, Minas Gerais, Brazil. Bull Geol Soc Am 58:1216–1217Google Scholar
  44. Robin MB, Day P (1967) Mixed valence chemistry — a survey and classification. Adv Inorg Chem Radiochem 10:247–422Google Scholar
  45. Rossman GR (1975) Spectroscopic and magnetic studies of ferric iron hydroxy sulfates: intensification of color in ferric iron clusters bridged by a single hydroxide ion. Am Mineral 60:698–704Google Scholar
  46. Rossman GR (1980) Pyroxene spectroscopy. In: Pyroxenes 93–115. Prewitt CT (ed) Book Crafters Inc., ChelseaGoogle Scholar
  47. Smith G, (1978) Evidence for absorption by exchange-coupled Fe2+-Fe3+ pairs in the near infra-red spectra of minerals. Phys Chem Minerals 3:375–383Google Scholar
  48. Smith G (1980) Evidence for optical absorption by Fe2+-Fe3+ interactions in MgO: Fe. Phys Status Solidi (A) 61:K1 91Google Scholar
  49. Smith G, Strens RGJ (1976) Intervalence-transfer absorption in some silicate, oxide, and phosphate minerals. In: The Physics and Chemistry of Minerals and Rocks. Strens RGJ (ed) John Wiley and Sons, New York, pp 583–612Google Scholar
  50. Takéuchi Y, Haga N, Bunno M (1983) X-ray study on polymorphism of ilvaite, HCaFe22+Fe3+O2[Si2O7]. Z Kristallogr 163:267–283Google Scholar
  51. Vochten R, de Grave E, Stoops G (1979) Petrographic, chemical and Mössbauer study of some oxidized vivianite nodules from Retie (Province of Antwerp, Belgium). Neues Jahrb Mineral Abh 137:208–222Google Scholar
  52. Winchell AN, Winchell H (1951) Elements of Optical Mineralogy. John Wiley and Sons, New YorkGoogle Scholar

Copyright information

© Springer-Verlag 1984

Authors and Affiliations

  • Georg Amthauer
    • 1
  • George R. Rossman
    • 2
  1. 1.Institut für MineralogieUniversität MarburgMarburgWest Germany
  2. 2.Division of Geological and Planetary SciencesCalifornia Institute of TechnologyPasadenaUSA

Personalised recommendations