Advertisement

Springer Nature is making SARS-CoV-2 and COVID-19 research free. View research | View latest news | Sign up for updates

Crystal field stabilization energies of almandine-pyrope and almandine-spessartine garnets determined by FTIR near infrared measurements

Abstract

The band positions of three partially overlapping Fe2+ spin-allowed transitions located between 4000 and 9000 cm−1 in almandine-pyrope and almandinespessartine garnets solid solutions were measured using near-infrared (NIR) spectroscopy. The crystal field stabilization energies (CFSE) along both binaries were calculated assuming a splitting of 1100 cm−1 for the lower orbitals. The CFSE show a slight increase along the almandine-spessartine binary from 3730 to 3810 cm−1 and a larger increase from 3730 to 3970 cm−1 for the almandine-pyrope binary. Dodecahedral Fe2+-site distortion increases with an increase in spessartine component and decreases with increasing pyrope component, in agreement with average dodecahedral site distortions determined from diffraction experiments. The excess CFSE's along both joins are negative. For the almandinespessartine binary they are small, but are about 3.5 times larger in magnitude along the join almandine-pyrope, where an interaction parameter of W= -2.9 KJ/mole has been derived from a symmetric mixing model. The excess CFSE are relatively small compared to the magnitudes of the excess enthalpies of mixing that have been assigned to garnet solid solutions. Moreover, they give no indication which could support the positive and asymmetric excess enthalpies of mixing that have been proposed for almandine-pyrope solid solutions.

This is a preview of subscription content, log in to check access.

References

  1. Armbruster Th, Geiger CA, Lager GA (1992) Single-crystal X-ray study of synthetic pyrope-almandine garnets at 100 and 293 K. Am Mineral 77:512–521

  2. Amthauer G, Annersten H, Hafner SS (1976) The Mössbauer spectrum of 57Fe in silicate garnets. Z. Kristallogr 143:14–55

  3. Herman RG (1990) Mixing properties of Ca-Mg-Fe-Mn garnets. Am Mineral 75:328–344

  4. Bevington PR (1969) Data Reduction and Error Analysis for the Physical Sciences. McGraw-Hill, New York

  5. Bloomfield P, Lawson AW, Rey C (1961) Crystal field splitting and covalent bonding in Fe++ silicate garnets. J Chem Phys 34:749–756

  6. Born L, Zemann J (1964) Abstandsberechnungen und gitterenergetische Berechnungen an Granaten. Beitr Mineral und Petrograph 10:2–23

  7. Burns RG (1970) Mineralogical Applications of Crystal Field Theory. Cambridge University Press, Cambridge, England

  8. Burns RG (1985) Thermodynamic data from crystal field spectra. In: Kieffer SW, Navrotsky A (ed) Reviews in Mineralogy. Microscopic to Macroscopic. Mineralogical Society of America, pp 277–316

  9. Burns RG (1993) Mineralogical Applications of Crystal Field Theory (2nd Edition). Cambridge University Press, Cambridge, England

  10. Clark SP (1957) Absorption spectra of some silicates in the visible and near infrared. Am Mineral 42:732–742

  11. Dunn TM, McClure DS, Pearson RG (1965) Some Aspects of Crystal Field Theory. Harper and Row, New York

  12. Evans BJ, Sergent EW Jr (1975) 57Fe NGR of Fe phases in “magnetic cassiterites”. Contrib Min Pet 53:183–194

  13. Ganguly J (1976) The energetics of natural garnet solid solutions. Contrib Min Pet 55:81–90

  14. Garner CD, Mabbs FE (1970) Studies in eight-coordination. Part I. Crystal-field energies in the D2d point-group. J Chem Soc (A): 1711–1716

  15. Geiger CA (1986) Thermodynamic mixing properties of almandine garnet solid solutions. Ph.D. thesis, University of Chicago 150 p

  16. Geiger CA (1993) 57Fe-Mössbauer spectroscopy of almandinespessartine garnets. Fall American Geophysical Union, EOS 74:676

  17. Geiger CA, Newton RC, Kleppa OJ (1987) Enthalpy of mixing of synthetic almandine-grossular and almandine-pyrope garnets from high-temperature solution calorimetry. Geochim Cosmochim Acta 51:1755–1763

  18. Geiger CA, Lottermoser W, Amthauer G (1990) A temperature dependent 57Fe Moessbauer study of synthetic almandine-grossular and almandine-pyrope garnets: A comparison. Third International Symposium of Experimental Mineralogy, Petrology and Geochemistry, Edinburgh, UK 75

  19. Geiger CA, Feenstra A (to be submitted) Molar volumes of mixing and crystal chemistry of almandine-pyrope and almandine-spessartine garnets. Am Mineral

  20. Geller S (1967) Crystal chemistry of the garnets. Z Kristallogr 125:1–47

  21. Hazony Y (1971) Hc-QS-IS correlations in octahedral iron compounds. Möss. Effect Method 7:147–166

  22. Huggins FE (1975) The 3d levels of ferrous ions in silicate garnets. Am Mineral 60:316–319

  23. Huggins FE (1976) Mossbauer studies of iron minerals under pressures of up to 200 kilobars In: Strens RGJ (ed) The physics and chemistry of rocks and minerals, Wiley, New York, 613–640

  24. Ingalls R (1964) Electric-field gradient tensor in ferrous compounds. Phys Rev 133a:787–795

  25. Manning PG (1967) The optical absorption spectra of the garnets almandine-pyrope and spessartine and some structural interpretations of mineralogical significance. Canadian Mineral 9:237–251

  26. Moore RK, White WB (1972) Electronic spectra of transition metal ions in silicate garnets. Canadian Mineral 22:791–811

  27. Newman DJ, Price DC, Runciman WA (1978) Superposition model analysis of the near infrared spectrum of Fe2+ in pyrope-almandine garnets. Am Mineral 63:1278–1281

  28. O'Neill HStC, Pownceby MI, Wall VJ (1989) Activity-composition relations in FeTiO3-MnTiO3 ilmenite solid solutions from EMF measurements at 1050–1300 K. Contr Mineral Petrology 103:216–222

  29. Novak GA, Gibbs GV (1971) The crystal chemistry of the silicate garnets. Am Mineral 56:791–825

  30. Randic M (1962) Ligand field splitting of d orbitals in eight coordinated complexes of dodecahedral structure. J Chem Phys 36:2094–2097

  31. Runciman WA, Sengupta D (1974) The spectrum of Fe2+ ions in silicate garnets. Am Mineral 59:563–566

  32. Skinner BJ (1956) Physical properties of end-members of the garnet group. Am Mineral 41:428–436

  33. Slack GA, Chrenko RM (1971) Optical absorption of natural garnets from 1000 to 30000 Wavenumbers. J Optical Soc Am 61:1325–1329

  34. Smith G, Langer K (1983) High pressure spectra up to 120 kbars of the synthetic garnet end members spessartine and almandine. N Jb Mineral Mh 12:541–555

  35. White WB, Moore RK (1972) Interpretation of the spin-allowed bands of Fe2+ silicate garnets. Am Mineral 57:1692–1710

  36. Zemann J (1962) Zur Kristallchemie der Granate. Beitr Mineral Petrograph 8:180–188

Download references

Author information

Correspondence to Charles A. Geiger.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Geiger, C.A., Rossman, G.R. Crystal field stabilization energies of almandine-pyrope and almandine-spessartine garnets determined by FTIR near infrared measurements. Phys Chem Minerals 21, 516–525 (1994). https://doi.org/10.1007/BF00203926

Download citation

Keywords

  • Spectroscopy
  • Enthalpy
  • Solid Solution
  • Mineral Resource
  • Material Processing