# The modular structure of pyroxenes

Abstract : The structures of pyroxenes can be described as cell-twins based on a common module (a layer) consisting of half the unit cell of the P2(1)/c polymorph. Atomic models of the different polymorphs are computed and the close similarity between the models and the corresponding experimental structures is shown. The cell-twin operations building the structures of pyroxenes are partial operations belonging to a special case of space groupoid which was called twinned space group'' in the pioneering studies by Ito started in 1935. The groupoid analysis of clino-, proto- and orthoenstatite is presented and the special place occupied by pyroxenes in the category of polytypes is discussed.
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https://hal.univ-lorraine.fr/hal-01531983
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Submitted on : Friday, June 2, 2017 - 11:27:49 AM
Last modification on : Thursday, October 8, 2020 - 8:40:04 AM

### Citation

Massimo Nespolo, Mois I. Aroyo. The modular structure of pyroxenes. European Journal of Mineralogy, Copernicus, 2016, 28 (1), pp.189-203. ⟨10.1127/ejm/2015/0027-2492⟩. ⟨hal-01531983⟩

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