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GEOREF RECORD

The infrared OH-stretching region of synthetic richterites in the system Na (sub 2) O-K (sub 2) O-CaO-MgO-SiO (sub 2) -H (sub 2) O-HF

J. L. Robert, G. Della-Ventura and J. L. Thauvin
The infrared OH-stretching region of synthetic richterites in the system Na (sub 2) O-K (sub 2) O-CaO-MgO-SiO (sub 2) -H (sub 2) O-HF
European Journal of Mineralogy (April 1989) 1 (2): 203-211

Abstract

All the synthesized amphiboles show a 'tremolite-type' band at 3670 cm (super -1) which suggests a partially vacant A-site. The departure from ideal compositions is interpreted as due to structural constraints. For the OH end-member Na-richterite the principal OH-stretching band is a single one centred at 3730 cm (super -1) but for K-richterite the band is split into two at 3735 and 3730 cm (super -1) . This is interpreted in terms of positional disorder of the K ion on the A-site. Along the (OH,F) solid solution, a new band appears at 3714 cm (super -1) whose intensity regularly increases as a function of X (sub F) . No band shift is observed. This modification of the IR spectra is interpreted as due to an ordered OH-F substitution. In K-richterites, OH groups which are in stronger interaction with K ions in the A(m) position are selectively replaced by F; the high-wave number component of the OH-stretching doublet disappears first. The strong anisotropy of cell dimension variations with increasing X (sub F) , in both the Na- and K-series, also reflects the weakening of repulsive interactions beween the hydroxyl proton H (super +) and the Na (super +) or K (super +) ion in the A-site, as F (super -) replaces OH (super -) .


ISSN: 0935-1221
Serial Title: European Journal of Mineralogy
Serial Volume: 1
Serial Issue: 2
Title: The infrared OH-stretching region of synthetic richterites in the system Na (sub 2) O-K (sub 2) O-CaO-MgO-SiO (sub 2) -H (sub 2) O-HF
Affiliation: CNRS-BRGM, Orleans, France
Pages: 203-211
Published: 198904
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 34
Accession Number: 1993-015421
Categories: Mineralogy of silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: 1 table
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United KingdomTwickenhamUKUnited Kingdom. Reference includes data from Geoline, Bundesanstalt fur Geowissenschaften und Rohstoffe, Hanover, Germany
Update Code: 1993
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