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

verfasst von

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.

Organisationseinheit(en)

Institut für Mineralogie

Externe Organisation(en)

Technische Universität Berlin
Helmholtz-Zentrum Berlin für Materialien und Energie GmbH

Typ

Artikel

Journal

European journal of mineralogy

Band

9

Seiten

67-82

Anzahl der Seiten

16

ISSN

0935-1221

Publikationsdatum

30.12.1996

Publikationsstatus

Veröffentlicht

Peer-reviewed

Ja

ASJC Scopus Sachgebiete

Geochemie und Petrologie

Elektronische Version(en)

https://doi.org/10.1127/ejm/9/1/0067 (Zugang: Geschlossen)