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The crystal-chemistry of high-aluminium titanites

Roberta Oberti, David C. Smith, Giuseppe Rossi and Franca Caucia
The crystal-chemistry of high-aluminium titanites
European Journal of Mineralogy (October 1991) 3 (5): 777-792


A study of 'high-aluminium titanites', where X (sub Al) = Al/(Al + Ti + Fe (super 3+) ) >= 0.25, has been made by single-crystal XRD on four samples from different localities. A refinement of a natural pure CaTiOSiO (sub 4) titanite from the Austrian Tyrol in the P2 (sub 1) /a space group (a 7.057, b 8.707, c 6.555 Angstrom, beta 113.81 degrees, V 368.5 Angstrom (super 3) ) is also reported. All of the high-Al titanites studied have A2/a space group symmetry with linear trends between geometrical and chemical parameters. Increasing Al content provokes a strong contraction of the octahedral site geometry. The decrease in the unit-cell volume from low to high X (sub Al) values is large; a specimen from Sierra de los Filabres, Spain, with Al (sub 2) O (sub 3) 9.62% (X (sub Al) 0.36) has a 7.038, b 8.635, c 6.514 Angstrom, beta 114.24 degrees, V 361.0 Angstrom (super 3) , suggesting that high-Al titanites are suitable minerals to incorporate OH at high P. Paragenetically, the occurrence of high-Al titanite is strongly correlated with the absence of anorthite-rich plagioclase.

ISSN: 0935-1221
Serial Title: European Journal of Mineralogy
Serial Volume: 3
Serial Issue: 5
Title: The crystal-chemistry of high-aluminium titanites
Affiliation: C.N.R., Centro di Studio per la Cristallografia Strutturale, Pavia, Italy
Pages: 777-792
Published: 199110
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 46
Accession Number: 1995-056211
Categories: Mineralogy of silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 4 tables
Secondary Affiliation: Museum National d'Histoire Naturelle, FRA, France
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United KingdomTwickenhamUKUnited Kingdom
Update Code: 199520
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