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High-pressure IR-spectra and the thermodynamic properties of chloritoid

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Published/Copyright: March 28, 2015
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American Mineralogist
From the journal American Mineralogist Volume 87 Issue 5-6

Abstract

Using IR radiation from a synchrotron source, high-quality absorbance spectra were obtained from polycrystalline powder of chloritoid (cld) from ambient conditions up to pressures of 10 GPa over 50 to 4000 cm-1. The idealized chemical composition of the chloritoid group is M2Al4O2(SiO4)2(OH)4 where M = Fe or Mg in our experiments. All of the 42 expected fundamental IR modes were observed. These data, combined with the response of the IR bands to substitutions of Fe for Mg, and of D for H, constrained the band assignments. Heat capacity (CP) and entropy (So) for the triclinic and monoclinic polymorphs of Fe- and Mg-cld were calculated from the Kieffer-type model, using our detailed band assignments. The calculated heat capacity and entropy for the monoclinic and triclinic polymorphs differ negligibly. The results at temperatures above 298 K are described by the following polynomial expressions in J/(mol·K): CP = 7.835 · 102 - 5.170 · 103T-0.5 - 1.648 · 107T-2 + 1.934 · 109T-3 for Mg-cld and CP = 7.848 · 102 - 5.185 · 103T-0.5 - 1.548 · 107T-2 + 1.783 · 109T-3 for Fe-cld. At room temperature, So = 293 J/mol·K for Mg-cld and 335 J/mol·K for Fe-cld. These values differ somewhat from entropy estimated from various internally consistent databases (-3 to -9% for Mg-cld and -9 to +5% for Fe-cld). However, using our new So and CP values in conjunction with the enthalpy of formation, Hf = -7101 kJ/mol for Mg-cld or Hf = -6422 kJ/mol for Fe-cld (estimated in this study), we can closely reproduce the experimental data for the reactions Mg-chloritoid + talc = clinochlore + kyanite (Chopin 1985) and Fe-chloritoid = almandine + diaspore + water (Vidal et al. 1994).

Received: 2001-7-31
Accepted: 2001-12-18
Published Online: 2015-3-28
Published in Print: 2002-5-1

© 2015 by Walter de Gruyter Berlin/Boston

Articles in the same Issue

  1. Formation of secondary pyrite and carbonate minerals in the Lower Williams Lake tailings basin, Elliot Lake, Ontario, Canada
  2. Hydroxyl in MgSiO3 akimotoite: A polarized and high-pressure IR study
  3. High-pressure IR-spectra and the thermodynamic properties of chloritoid
  4. Infrared and Raman study of interlayer anions CO32–, NO3–, SO42– and ClO4– in Mg/Al-hydrotalcite
  5. Effect of Fe oxidation state on the IR spectra of Garfield nontronite
  6. High-pressure single-crystal X-ray diffraction study of katoite hydrogarnet: Evidence for a phase transition from Ia3d →I4̅3d symmetry at 5 GPa
  7. The high-temperature P21/c-C2/c phase transition in Fe-free pyroxene (Ca0.15Mg1.85Si2O6): Structural and thermodynamic behavior
  8. Thermodynamics and stability of pseudobrookite-type MgTi2O5 (karrooite)
  9. Molecular orbital calculations on aluminosilicate tricluster molecules: Implications for the structure of aluminosilicate glasses
  10. Surface structures, stabilities, and growth of magnesian calcites: A computational investigation from the perspective of dolomite formation
  11. Spinels and other oxides in Mn-rich rocks from the Hutter Mine, Pittsylvania County, Virginia, U.S.A.: Implications for miscibility and solvus relations among jacobsite, galaxite, and magnetite
  12. An occurrence of igneous orthorhombic amphibole, Eriksberg gabbro, southern Sweden
  13. Crystal chemistry of Cr3+-V3+-rich clinopyroxenes
  14. The crystal structures of cesanite and its synthetic analogue—A comparison
  15. Disordered distribution of Cu in the crystal structure of leightonite, K2Ca2Cu(SO4)4 · 2H2O
  16. Neustädtelite and cobaltneustädtelite, the Fe3+ - and Co2+ -analogues of medenbachite
  17. Ciprianiite and mottanaite-(Ce), two new minerals of the hellandite group from Latium (Italy)
  18. Re-definition, nomenclature and crystal-chemistry of the hellandite group
  19. The new mineral baumstarkite and a structural reinvestigation of aramayoite and miargyrite
  20. Letters. Isotopic and elemental partitioning of boron between hydrous fluid and silicate melt
  21. Experimental evidence of three coexisting immiscible fluids in synthetic granitic pegmatite
  22. Quantifying surface areas of clays by atomic force microscopy
  23. A new high-pressure phase of FeSi
https://doi.org/10.2138/am-2002-5-603

Articles in the same Issue

  1. Formation of secondary pyrite and carbonate minerals in the Lower Williams Lake tailings basin, Elliot Lake, Ontario, Canada
  2. Hydroxyl in MgSiO3 akimotoite: A polarized and high-pressure IR study
  3. High-pressure IR-spectra and the thermodynamic properties of chloritoid
  4. Infrared and Raman study of interlayer anions CO32–, NO3–, SO42– and ClO4– in Mg/Al-hydrotalcite
  5. Effect of Fe oxidation state on the IR spectra of Garfield nontronite
  6. High-pressure single-crystal X-ray diffraction study of katoite hydrogarnet: Evidence for a phase transition from Ia3d →I4̅3d symmetry at 5 GPa
  7. The high-temperature P21/c-C2/c phase transition in Fe-free pyroxene (Ca0.15Mg1.85Si2O6): Structural and thermodynamic behavior
  8. Thermodynamics and stability of pseudobrookite-type MgTi2O5 (karrooite)
  9. Molecular orbital calculations on aluminosilicate tricluster molecules: Implications for the structure of aluminosilicate glasses
  10. Surface structures, stabilities, and growth of magnesian calcites: A computational investigation from the perspective of dolomite formation
  11. Spinels and other oxides in Mn-rich rocks from the Hutter Mine, Pittsylvania County, Virginia, U.S.A.: Implications for miscibility and solvus relations among jacobsite, galaxite, and magnetite
  12. An occurrence of igneous orthorhombic amphibole, Eriksberg gabbro, southern Sweden
  13. Crystal chemistry of Cr3+-V3+-rich clinopyroxenes
  14. The crystal structures of cesanite and its synthetic analogue—A comparison
  15. Disordered distribution of Cu in the crystal structure of leightonite, K2Ca2Cu(SO4)4 · 2H2O
  16. Neustädtelite and cobaltneustädtelite, the Fe3+ - and Co2+ -analogues of medenbachite
  17. Ciprianiite and mottanaite-(Ce), two new minerals of the hellandite group from Latium (Italy)
  18. Re-definition, nomenclature and crystal-chemistry of the hellandite group
  19. The new mineral baumstarkite and a structural reinvestigation of aramayoite and miargyrite
  20. Letters. Isotopic and elemental partitioning of boron between hydrous fluid and silicate melt
  21. Experimental evidence of three coexisting immiscible fluids in synthetic granitic pegmatite
  22. Quantifying surface areas of clays by atomic force microscopy
  23. A new high-pressure phase of FeSi
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