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Structural analysis of an obsidian by X-ray diffraction method

Masayuki Okuno, Hidefumi Iwatsuki and Takeo Matsumoto
Structural analysis of an obsidian by X-ray diffraction method
European Journal of Mineralogy (December 1996) 8 (6): 1257-1264

Abstract

The average local structure of an obsidian has been analysed using X-ray radial distribution function and compared with the structure of a fused obsidian glass. The T-O distances of these samples are close to the average T-O distance of SiO (sub 4) and AlO (sub 4) tetrahedra; the T-T distances and calculated T-O-T angles are similar to those of SiO (sub 2) , albite and orthoclase glasses, but the T-O-T angle is larger than that of anorthite glass. The basic structure of the obsidian is therefore explained as a stuffed framework structure model with six-membered rings of TO (sub 4) (T = Si and Al) tetrahedra. Large deformations of TO (sub 4) tetrahedra and their linkages occur during the crystallization process below the melting point. It is supposed that repolymerization of supercooled liquid occurred at the beginning of its crystallization process.


ISSN: 0935-1221
Serial Title: European Journal of Mineralogy
Serial Volume: 8
Serial Issue: 6
Title: Structural analysis of an obsidian by X-ray diffraction method
Affiliation: Kanazawa University, Department of Earth Sciences, Kanazawa, Japan
Pages: 1257-1264
Published: 199612
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 35
Accession Number: 1997-018101
Categories: Igneous and metamorphic petrology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: 2 tables
N40°00'00" - N51°00'00", W123°00'00" - W120°30'00"
N42°00'00" - N46°19'60", W124°34'60" - W116°34'60"
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United KingdomTwickenhamUKUnited Kingdom
Update Code: 199706
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