Original paper

Crystal chemistry and infrared spectroscopy in the OH-stretching region of synthetic staurolites

Koch-Müller, Monika; Langer, Klaus; Behrens, Harald; Schuck, Gotz

European Journal of Mineralogy Volume 9 Number 1 (1996), p. 67 - 82

31 references

published: Dec 30, 1997
manuscript accepted: Oct 21, 1996
manuscript received: Jan 15, 1996

DOI: 10.1127/ejm/9/1/0067

BibTeX file

ArtNo. ESP147050901007, Price: 29.00 €

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Abstract

Abstract Fe-staurolite synthesized in the pressure range 5 to 25 kbar at 680 ºC was analysed by microprobe and by a titration method (for water-contents) which uses the "Karl-Fischer" reaction and also characterized by FT-infrared powder spectroscopy in the OH-stretching region (3000-4000 cm-1). The study shows that the stoichiometry of the synthetic Fe-staurolites depends on the pressure of equilibration, with Fe pfu decreasing with increasing pressure, according to the heterovalent substitution of Fe2+ by Al3+ in the T2 site. This chargeincreasing substitution is combined with charge-reducing substitutions in the "kyanite'Mayer and by vacancies in the proton site HI. The incorporation of Al in T2 is supported by peculiarities of the IR-spectra in the range of the OH-valence vibrations. Mg- and Zn-staurolite were synthesized at 25 kbar and 700 °C and investigated by infrared spectroscopy. The comparison of the infrared spectra of synthetic Fe-, Mg- and Zn-staurolites shows that there is a significant amount of Fe2+, Mg and Zn in the respective M2 sites

Keywords

synthetic staurolitesstaurolite stoichiometryKarl-Fischer titrationinfrared spectroscopyOH-stretching region