MS13-P04 New insights into Eugsterite’s structure from SC-ED and PXRD data CRISTOBAL VERDUGO-ESCAMILLA (Laboratorio de Estudios Cristalográficos, IACT, CSIC-UGR, Granada, Spain) Stef Smeets (Department of Materials and Environmental Chemistry, Stockholm University, Stockholm, Sweden) Joaquín Criado-Reyes (Laboratorio de Estudios Cristalográficos, IACT, CSIC-UGR, Granada, Spain) M. O. Cichocka (Department of Materials and Environmental Chemistry, Stockholm University, Stockholm, Sweden) Duane Choquesillo-Lazarte (Laboratorio de Estudios Cristalográficos, IACT, CSIC-UGR, Granada, Spain) Fermín Otálora (Laboratorio de Estudios Cristalográficos, IACT, CSIC-UGR, Granada, Spain) Juan Manuel García-Ruíz (Laboratorio de Estudios Cristalográficos, IACT, CSIC-UGR, Granada, Spain)email: cristobal.verdugo@csic.esEugsterite is a mineral commonly associated with halite, thenardite, bloedite, gypsum, glauberite and nesquehonite and occurs in some parts of Kenya and in the Konya Basin in Turkey Its crystal structure is unknown and the only information is a list of d spacings and intensities obtained from an X-ray powder pattern of an impure synthetic sample (Vergouwen, 1981).

In this work, we have confirmed the difficulty on purifying eugsterite, reason because the structure solution had to be attempted from Single Crystal Electron Diffraction (SCED) data of a multiphasic sample where only single crystals of eugsterite were measured with the continuous rotation method (Wang et al., 2017).

The structural model obtained from the SCED data was lately used to refine this structure through a Powder X-ray Diffraction (PXRD) dataset of an impure sample containing gypsum, halite and thenardite in addition to eugsterite.

The structure of Eugsterite consists of two crystallographically independent CaNa(SO4) layers along the xy-plane. One layer can be described by two linked columns of NaO6 polyhedra interconnected via cornersharing SO4 tetrahedra. The other layer is described as columns formed by face-sharing NaO6 polyhedra in trigonal antiprismatic arrangement interconnected via cornersharing SO4 tetrahedron. The layers are interlinked via columns of edge-sharing CaO8 polyhedra.
References:

Vergouwen, L. (1981). Am. Miner. 66, 632–636.

Wang, Y., Takki, S., Cheung, O., Xu, H., Wan, W., Öhrström, L. & Ken Inge, A. (2017). Chem. Commun. 53, 7018–7021.
Keywords: Eugsterite, mineral, PXRD