Abstract
The structure of an intermediate orthopyroxene, Mg 0.93 Fe 1.07 Si 2 O 6 with cell dimensions a = 18.310, b = 8.927, c = 5.226 Å; space group: Pbca , derived from a high-grade metamorphic rock, has been refined by the method of least squares using three-dimensional intensity data. The R factor for 1028 reflections is 0.118. The average standard deviation of M–O, as well as Si–O bond lengths is 0.014 Å. Mg 2+ and Fe 2+ are virtually completely ordered, the ordering scheme being the same as that proposed by G hose (1962). The M 1 site, corresponding to the Mg site in diopside, CaMgSi 2 O 6 , contains 85% Mg 2+ and 15% Fe 2+ and the M 2 site, corresponding to the Ca site in diopside, contains 90% Fe 2+ and 10% Mg 2+ . M 2 –O 2 (2.07 Å) and M 2 –O 5 (2.04 Å) bonds are significantly shorter than the sum of P auling 's crystal radii (2.16 Å) and have considerable covalent character. The two crystallographically distinct silicate chains have slightly different configurations, caused by slight rotations of Si 1 and Si 2 tetrahedra, with Si 1 –O 1 and Si 2 –O 4 as axes. The average Si–O bond length is 1.63 Å. The non-bridging Si–O bonds (1.60 Å) are significantly shorter than the bridging Si–O bonds (1.66 Å).
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
