Home Physical Sciences 3T-phlogopite from Kasenyi kamafugite (SW Uganda): EPMA, XPS, FTIR, and SCXRD study
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3T-phlogopite from Kasenyi kamafugite (SW Uganda): EPMA, XPS, FTIR, and SCXRD study

  • Emanuela Schingaro , Maria Lacalamita , Fernando Scordari EMAIL logo and Ernesto Mesto
Published/Copyright: March 7, 2015
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American Mineralogist
From the journal American Mineralogist Volume 98 Issue 4

Abstract

A 3T mica polytype from Kasenyi (southwest Uganda), kamafugite, was studied by electron probe microanalysis (EPMA), single-crystal X-ray diffraction (SCXRD), micro-Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) to characterize its crystal chemistry and the relationships with phlogopites from the same rock but showing different stacking sequence and to get insights into factors affecting polytypism in Ugandan phlogopites. EPMA data gave: SiO2 = 38.7(2), Al2O3 = 13.08(9), MgO = 20.4(2), TiO2 = 4.8(1), MnO = 0.03(3), FeOtot = 5.51(9), Cr2O3 = 0.90(7), NiO = 0.11(5), SrO = 0.03(3), ZnO = 0.04(3), ZrO2 = 0.01(2), K2O = 9.64(5), Na2O = 0.29(1), BaO = 0.15(5), F = 0.13(5), and Cl = 0.01(1) wt%. The analyzed sample may be classified as a Ti-rich phlogopite. X-ray photoelectron spectroscopy provided Fe3+/Fe2+ and O2-/OH equal to ~0.75 and 7.14, respectively, which are in agreement with the results of previous Mössbauer investigation on the BU1 phlogopites from the same rock and with the structural formula of the studied crystal. Infrared spectra showed a shoulder at ~3660 cm-1 in the OH− stretching region (~3740-3600 cm-1), which is assigned to MgMgFe3+-OH−-K-O2- local configurations. No evidences of vacancy substitutions were observed. Structure refinement based on single-crystal X-ray diffraction data was performed in space group P3112 using anisotropic displacement parameters and converged to R1 = 4.34 and wR2 = 3.33%. Unitcell parameters are: a = b = 5.3235(3) and c = 30.188(2) Å. Geometrical and chemical considerations point to a disordered cation distribution over T1 and T2 tetrahedral sites, whereas partial cation ordering characterizes the octahedral sites with high-charge cations preferentially located as expected on M2 and M3. Tetrahedral bond length distortion and angular variance parameters describe more distorted polyhedra in 3T polytype than those found in coexisting 1M and 2M1 polytypes. Finally, the overall crystal-chemical features indicate the occurrence of the following substitution mechanisms in the studied sample: Ti-oxy [VIM2++2(OH)- ↔ VITi4++2(O2-)+H2↑] and Al, Fe3+, Croxy [VIM2++(OH)- ↔ VIM3++O2-+½(H2)↑]; Al, Fe3+-Tschermak [VIM2++IVSi4+ ↔ VI(Al3+, Fe3+)+IVAl3+]; XIIK++IVAl3+ ↔ IVSi4++XII⃞; tetraferriphlogopite [IVFe3+↔ IVAl].

Keywords : 3T-phlogopite; SCXRD; EPMA; FTIR; XPS; crystal chemistry; cation partitioning
Received: 2012-7-3
Accepted: 2012-12-9
Published Online: 2015-3-7
Published in Print: 2013-4-1

© 2015 by Walter de Gruyter Berlin/Boston

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  3. Actinides in Geology, Energy, and the Environment. Revision of the symmetry and the crystal structure of čejkaite, Na4(UO2)(CO3)3
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  6. Transformation of graphite to lonsdaleite and diamond in the Goalpara ureilite directly observed by TEM
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  24. Hydrogen incorporation in crystalline zircon: Insight from ab initio calculations
  25. The vibrational features of hydroxylapatite and type A carbonated apatite: A first principle contribution
  26. STEM investigation of exsolution lamellae and “c” reflections in Ca-rich dolomite from the Platteville Formation, western Wisconsin
  27. Karenwebberite, Na(Fe2+,Mn2+)PO4, a new member of the triphylite group from the Malpensata pegmatite, Lecco Province, Italy
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  29. Static disorders of atoms and experimental determination of Debye temperature in pyrope: Low- and high-temperature single-crystal X-ray diffraction study—Discussion
  30. Static disorders of atoms and experimental determination of Debye temperature in pyrope: Low- and high-temperature single-crystal X-ray diffraction study—Reply
https://doi.org/10.2138/am.2013.4283
Keywords for this article
3T-phlogopite; SCXRD; EPMA; FTIR; XPS; crystal chemistry; cation partitioning

Articles in the same Issue

  1. Highlight and Breakthrough. A fresh look at crystals in the Bishop Tuff
  2. Actinides in Geology, Energy, and the Environment. Remobilization of U and REE and the formation of secondary minerals in oxidized U deposits
  3. Actinides in Geology, Energy, and the Environment. Revision of the symmetry and the crystal structure of čejkaite, Na4(UO2)(CO3)3
  4. Characterization of ferric arsenate-sulfate compounds: Implications for arsenic control in refractory gold processing residues
  5. Crystal structure and chemistry of skarn-associated bismuthian vesuvianite
  6. Transformation of graphite to lonsdaleite and diamond in the Goalpara ureilite directly observed by TEM
  7. Quartz nanocrystals in the 2.48 Ga Dales Gorge banded iron formation of Hamersley, Western Australia: Evidence for a change from submarine to subaerial volcanism at the end of the Archean
  8. Synthesis and characterization of amphiboles along the tremolite–glaucophane join
  9. Elasticity of franklinite and trends for transition-metal oxide spinels
  10. Redox systematics of martian magmas with implications for magnetite stability
  11. Hydrogen incorporation and the oxidation state of iron in ringwoodite: A spectroscopic study
  12. Hydrous ringwoodite to 5 K and 35 GPa: Multiple hydrogen bonding sites resolved with FTIR spectroscopy
  13. Calibration of zircon as a Raman spectroscopic pressure sensor to high temperatures and application to water-silicate melt systems
  14. Computational study of the elastic behavior of the 2M1 muscovite-paragonite series
  15. Vanadium L2,3 XANES experiments and first-principles multielectron calculations: Impact of second-nearest neighboring cations on vanadium-bearing fresnoites
  16. A time-resolved X-ray diffraction study of Cs exchange into hexagonal H-birnessite
  17. Grain-boundary diffusion rates inferred from grain-size variations of quartz in metacherts from a contact aureole
  18. On the use of unpolarized infrared spectroscopy for quantitative analysis of absorbing species in birefringent crystals
  19. A computational model of cation ordering in the magnesioferrite-qandilite (MgFe2O4- Mg2TiO4) solid solution and its potential application to titanomagnetite (Fe3O4-Fe2TiO4)
  20. 3T-phlogopite from Kasenyi kamafugite (SW Uganda): EPMA, XPS, FTIR, and SCXRD study
  21. Revision of the crystal structure and chemical formula of haiweeite, Ca(UO2)2(Si5O12)(OH)2·6H2O
  22. Cation arrangement in the octahedral and tetrahedral sheets of cis-vacant polymorph of dioctahedral 2:1 phyllosilicates by quantum mechanical calculations
  23. High-pressure phase transitions of Fe3–xTixO4 solid solution up to 60 GPa correlated with electronic spin transition
  24. Hydrogen incorporation in crystalline zircon: Insight from ab initio calculations
  25. The vibrational features of hydroxylapatite and type A carbonated apatite: A first principle contribution
  26. STEM investigation of exsolution lamellae and “c” reflections in Ca-rich dolomite from the Platteville Formation, western Wisconsin
  27. Karenwebberite, Na(Fe2+,Mn2+)PO4, a new member of the triphylite group from the Malpensata pegmatite, Lecco Province, Italy
  28. The crystal structure of ramdohrite, Pb5.9Fe0.1Mn0.1In0.1Cd0.2Ag2.8Sb10.8S24: A new refinement
  29. Static disorders of atoms and experimental determination of Debye temperature in pyrope: Low- and high-temperature single-crystal X-ray diffraction study—Discussion
  30. Static disorders of atoms and experimental determination of Debye temperature in pyrope: Low- and high-temperature single-crystal X-ray diffraction study—Reply
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