Raman and NMR spectroscopic characterization of high-pressure K-cymrite (KAlSi 3O 8.H 2O) and its anhydrous form (kokchetavite)

Masami Kanzaki, Xianyu Xue, Julien Amalberti, Qian Zhang

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13 Citations (Scopus)

Abstract

Objective: To facilitate identification of high-pressure K-cymrite (KAlSi 3O 8.H 2O) phase and its anhydrous form (kokch tavite) in natural rocks, we have synthesized both phases and have characterized them by micro-Raman and NMR spectroscopy K-cymrite was synthesized at 5 GPa and 800 °C. Kokchetavite was obtained by dehydrating K-cymrite at ambient pressure and 550 °C. The 1H MAS and 1H- 29Si CP MAS NMR spectra of K-cymrite are consistent with the reported crystal structure that co tains H 2O molecules and has a disordered Si-Al distribution. The Raman spectra obtained under ambient conditions for K-cy rite (and kokchetavite) contain major peaks at 114.0 (109.1), 380.2 (390.0) and 832.5 (835.8) cm -1. For K-cymrite, OH stretching vibration is also observed at 3541 cm -1 with a shoulder at 3623 cm -1. The Raman spectrum for kokchetavite is consistent with that previously reported for a natural sample found as inclusions in clinopyroxenes and garnets in a garnet-pyroxene rock. However, the data for K-cymrite are inconsistent with the Raman features of a previously reported "relict K-cymrite in K-feldspar" from an eclogite. Pressure- and temperature-dependencies of the Raman shifts for the strongest peak of both phases are also reported.

Original languageEnglish
Pages (from-to)114-119
Number of pages6
JournalJournal of Mineralogical and Petrological Sciences
Volume107
Issue number2
DOIs
Publication statusPublished - 2012

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Keywords

  • High pressure
  • K-cymrite
  • KAlSi O .H O
  • Kokchetavite
  • NMR
  • Raman

ASJC Scopus subject areas

  • Geophysics
  • Geology

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