Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (7) Citing Articles via Google Scholar Google Scholar Articles by NESTOLA, F. Articles by TRIBAUDINO, M. Search for Related Content GeoRef GeoRef Citation

The structure of Pbca orthopyroxenes along the join diopside-enstatite (CaMgSi₂O₆-Mg₂Si₂O₆)

Dipartimento di Scienze Mineralogiche e Petrologiche, Università di Torino, Via Valperga Caluso 35, I-10125 Torino, Italy

^* e-mail: mario.tribaudino{at}unito.it

The crystal structure of two synthetic orthopyroxenes, with compositions Ca_0.04Mg_1.96Si₂O₆ and Ca_0.07Mg_1.93Si₂O₆ has been refined by single-crystal X-ray diffraction [R(4) = 2.7 and 3.6 %, respectively]. TEM observation has shown the presence of irregularly repeated P2₁/c clinopyroxene lamellae, oriented parallel to (100), in agreement with the presence of reflections with 1 = 2n violating the b glide plane.

Significant electron density residuals close to the M2 and O2B sites were found, allowing split site refinement for the sample with composition Ca_0.07Mg_1.93Si₂O_6. M2-O bond lengths for average and local configurations for Ca and Mg have been found to be very similar to those of clinopyroxenes along the join diopside-enstatite. The increasing presence, due to the substitution of Ca for Mg in the M2 site, of Ca configurations in orthopyroxene that are similar to the average ones in Ca-richer C2/c clinopyroxene reduces the stability of the orthopyroxene phase.

Key-words: orthopyroxene, split site refinement, diopside-enstatite, crystal structure, X-ray single-crystal diffraction..

This article has been cited by other articles:

				S. Ohi, A. Miyake, N. Shimobayashi, M. Yashima, and M. Kitamura An isosymmetric phase transition of orthopyroxene found by high-temperature X-ray diffraction American Mineralogist, October 1, 2008; 93(10): 1682 - 1685. [Abstract] [Full Text] [PDF]

				F. Nestola, M. Tribaudino, T. Boffa Ballaran, C. Liebske, and M. Bruno The crystal structure of pyroxenes along the jadeite hedenbergite and jadeite aegirine joins American Mineralogist, August 1, 2007; 92(8-9): 1492 - 1501. [Abstract] [Full Text] [PDF]

				J.-P. Perrillat, F. Nestola, S. V. Sinogeikin, and J. D. Bass Single-crystal elastic properties of Ca0.07Mg1.93Si2O6 orthopyroxene American Mineralogist, January 1, 2007; 92(1): 109 - 113. [Abstract] [Full Text] [PDF]

				F. Nestola, G. D. Gatta, and T. B. Ballaran The effect of Ca substitution on the elastic and structural behavior of orthoenstatite American Mineralogist, May 1, 2006; 91(5-6): 809 - 815. [Abstract] [Full Text] [PDF]

				M. TRIBAUDINO, F. NESTOLA, and H. OHASHI High temperature single crystal investigation in a clinopyroxene of composition (Na0.5Ca0.5)(Cr0.5Mg0.5)Si2O6 European Journal of Mineralogy, April 1, 2005; 17(2): 297 - 304. [Abstract] [Full Text] [PDF]