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Crystal chemical and structural variations in orthopyroxenes from different petrogenetic environments

Sara Bertolo and Paolo Nimis
Crystal chemical and structural variations in orthopyroxenes from different petrogenetic environments
European Journal of Mineralogy (August 1993) 5 (4): 707-719

Abstract

Seventeen orthopyroxenes (from 2 volcanic rocks, 13 granulites, 1 mantle xenolith, 1 synthetic pyrolite) were analysed by XRD and EPMA to obtain accurate site occupancies and to define the relationships between structural and chemical variations over a wide range of compositions. The data are combined with earlier analyses of 22 orthopyroxenes and show that the geometry of each polyhedron is not only a function of polyhedron cations but is also constrained by geometric variations in the adjacent sites. Octahedral cation-oxygen distances generally increase non-linearly with increasing Mg right arrow (Fe (super 2+) + Mn) substitution. Geometric variations in the tetrahedral chains are ascribed mainly to variations of the M2 polyhedron and (for SiB only) to the Si left/right arrow Al (super iv) substitution [M.M. 37-90].


ISSN: 0935-1221
Serial Title: European Journal of Mineralogy
Serial Volume: 5
Serial Issue: 4
Title: Crystal chemical and structural variations in orthopyroxenes from different petrogenetic environments
Affiliation: Universita di Padova, Dipartimento di Mineralogia e Petrologia, Padua, Italy
Pages: 707-719
Published: 199308
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 23
Accession Number: 1993-023689
Categories: Mineralogy of silicatesIgneous and metamorphic petrology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 1 table
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United KingdomTwickenhamUKUnited Kingdom
Update Code: 1993
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