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A reinvestigation of mayenite from the type locality, the Ettringer Bellerberg Volcano near Mayen, Eifel District, Germany

E. V. Galuskin, J. Kusz, T. Armbruster, R. Bailau, I. O. Galuskina, B. Ternes and M. Murashko
A reinvestigation of mayenite from the type locality, the Ettringer Bellerberg Volcano near Mayen, Eifel District, Germany
Mineralogical Magazine (June 2012) 76 (3): 707-716

Abstract

New electron-microprobe analyses of mayenite from the Ettringer Bellerberg volcano near Mayen in the Eifel district, Germany have high Cl contents and Raman spectroscopy indicates the presence of OH groups. Neither of these components is included in the generally accepted chemical formula, Ca (sub 12) Al (sub 14) O (sub 33) . A refinement of the crystal structure by single-crystal X-ray methods reveals a previously unrecognized partial substitution. The O2 site which forms one of the apices of an AlO (sub 4) tetrahedron (with 3XO1 sites) is replaced by 3XO2a sites, which change the coordination of the central Al atom from tetrahedral to octahedral. This substitution is related to partial hydration of Ca (sub 12) Al (sub 14) O (sub 32) Cl (sub 2) according to the isomorphic scheme (O (super 2-) + Cl (super -) )<-->3(OH) (super -) . The revised composition of Eifel mayenite is best described by the formula Ca (sub 12) Al (sub 14) O (sub 32-x) Cl (sub 2-x) (OH) (sub 3x) (x approximately 0.75); the original formula, Ca (sub 12) Al (sub 14) O (sub 33) , is inadequate. The analysed mineral can be considered to consist of endmember Ca (sub 12) Al (sub 14) O (sub 32) Cl (sub 2) (62.5 mol.%) and endmember Ca (sub 12) Al (sub 14) O (sub 30) (OH) (sub 6) (37.5 mol.%).


ISSN: 0026-461X
EISSN: 1471-8022
Coden: MNLMBB
Serial Title: Mineralogical Magazine
Serial Volume: 76
Serial Issue: 3
Title: A reinvestigation of mayenite from the type locality, the Ettringer Bellerberg Volcano near Mayen, Eifel District, Germany
Affiliation: University of Silesia, Department of Geochemistry, Mineralogy and Petrography, Sosnowiec, Poland
Pages: 707-716
Published: 201206
Text Language: English
Publisher: Mineralogical Society, London, United Kingdom
References: 36
Accession Number: 2012-092178
Categories: Mineralogy of non-silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 5 tables
N50°00'00" - N50°30'00", E06°19'60" - E07°19'60"
Secondary Affiliation: University of Bern, CHE, SwitzerlandDienstleistungszentrum Laendlicher Raum, DEU, Germany
Country of Publication: United Kingdom
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, Copyright, Mineralogical Society of Great Britain and Ireland. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201248
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