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

authored by: Monika Koch-Müller, Klaus Langer, Harald Behrens, Götz Schuck
Abstract: Fe-staurolite synthesized in the pressure range 5 to 25 kbar at 680 °C 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 charge-increasing substitution is combined with charge-reducing substitutions in the "kyanite"-layer and by vacancies in the proton site H1. 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.
Organisation(s): Institute of Mineralogy
External Organisation(s): Technische Universität Berlin
Helmholtz-Zentrum Berlin für Materialien und Energie (HZB)
Type: Article
Journal: European journal of mineralogy
Volume: 9
Pages: 67-82
No. of pages: 16
ISSN: 0935-1221
Publication date: 30.12.1996
Publication status: Published
Peer reviewed: Yes
ASJC Scopus subject areas: Geochemistry and Petrology
Electronic version(s): https://doi.org/10.1127/ejm/9/1/0067 (Access: Closed)

BibTeX

@article{dfe512c147a343fea2dd8963a466098e,
title = "Crystal chemistry and infrared spectroscopy in the OH-stretching region of synthetic staurolites",
abstract = "Fe-staurolite synthesized in the pressure range 5 to 25 kbar at 680 °C 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 charge-increasing substitution is combined with charge-reducing substitutions in the {"}kyanite{"}-layer and by vacancies in the proton site H1. 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 = "Infrared spectroscopy, Karl-Fischer titration, OH-stretching region, Staurolite stoichiometry, Synthetic staurolites",
author = "Monika Koch-M{\"u}ller and Klaus Langer and Harald Behrens and G{\"o}tz Schuck",
year = "1996",
month = dec,
day = "30",
doi = "10.1127/ejm/9/1/0067",
language = "English",
volume = "9",
pages = "67--82",
journal = "European journal of mineralogy",
issn = "0935-1221",
publisher = "E. Schweizerbart'sche Verlagsbuchhandlung",
number = "1",
}