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Synthesis and characterization of amphiboles along the tremolite–glaucophane join

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Published/Copyright: March 7, 2015
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American Mineralogist
From the journal American Mineralogist Volume 98 Issue 4

Abstract

Actinolite and glaucophane are the principal amphiboles in greenschist- and blueschist-facies metamafic rocks, respectively, and constitute an important mineral pair for deducing the conditions of medium- and high-pressure metamorphism. Here we present the crystal-chemical properties of amphiboles synthesized along the tremolite-glaucophane join as an important starting point for the more chemically complex samples occurring in nature. Amphiboles were synthesized in 10 mol% increments at conditions ranging from 840 °C and 0.6 GPa for tremolite-rich to 750 °C and 2.5 GPa for glaucophane-rich amphiboles. The amphibole yields were generally high (~95 wt%), though minor quartz, pyroxene, and amorphous material (either glass or quenched solute) were often present. Electron microprobe analysis of the amphibole showed that deviations from the nominal or intended compositions occurred, with the observed compositions showing solid solution primarily toward the katophorite component and reaching a maximum near the middle of the join. Unit-cell dimensions showed a pronounced positive deviation from ideality, even after (linear) correction for the non-join components, suggesting a strong tendency toward exsolution. Single-crystal refinements of a couple of selected amphiboles confirmed the deviation from nominal composition and confirmed the presence of ANa, TAl, and CAl, the latter disordered between the M(2) and M(3) sites. Infrared spectra in the OH-stretching region were measured on samples that were heated to 250-350 °C to remove absorbed moisture. The spectra consist of a main band centered in the 3675-3660 cm-1 region and two minor absorptions on both sides of the dominant central peak, which are centered at 3720 and 3640 cm-1 and can be attributed to OH next to ANa and CAl, respectively. The main band is evidently composed of several overlapping components due to local arrangements of B cations typical of tremolite, CaCa, glaucophane, NaNa, and cummingtonite, MgMg. Examination of several intermediate amphiboles by both single-crystal XRD and by high-resolution TEM analysis could not identify evidence of reflections or ordered domains that would violate the C2/m symmetry of the end-member amphiboles. Comparing the compositions of the synthetic amphiboles from this study with winchite-rich amphiboles in nature shows that deviations from the tremolite-glaucophane join are common. The inability to make pure winchite or even winchite-rich amphiboles on the tremolite-glaucophane join suggests that this structure is unstable.

Keywords : Glaucophane; tremolite; winchite; katophorite; high-pressure metamorphism; unit-cell dimensions; short-range order; HRTEM; FTIR
Received: 2012-6-28
Accepted: 2012-11-2
Published Online: 2015-3-7
Published in Print: 2013-4-1

© 2015 by Walter de Gruyter Berlin/Boston

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
https://doi.org/10.2138/am.2013.4281
Keywords for this article
Glaucophane; tremolite; winchite; katophorite; high-pressure metamorphism; unit-cell dimensions; short-range order; HRTEM; FTIR

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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