Krivovichev, S. V., Yakovenchuk, V. N., Armbruster, T., Pakhomovskiy, Y. A. and Depmeier, W. (2003) Crystal structure of the K, Ti analogue of ilimaussite-(Ce), (Ba,K,Na,Ca)(11-12)(REE,Fe,Th)(4)(Ti,Nb)(6)(Si6O18)(4)(OH)(12)center dot 4.5 H2O: revision of structure model and structural formula. Zeitschrift Fur Kristallographie, 218 (6). pp. 392-396. DOI 10.1524/zkri.218.6.392.20721.

Abstract

The crystal structure of the K, Ti analogue of ilimaussite-(Ce), (Ba,K,Na,Ca)(11-12)(REE,Fe,Th)(4)(Ti,Nb)(6)(Si6O18)(4)(OH)(12) 4.5 H2O, from the Yukspor mountain, Khibiny massif, Kola peninsula, Russia, has been solved by direct methods and refined to R-1 = 0.077 on the basis of 1762 reflections with \F-0\ greater than or equal to 4sigmaF. The mineral is rhombohedral, R32, a 10.708(2), c = 60.073(l 1) Angstrom, V = 5965.2(17) Angstrom(3). The structure is based upon a heteropolyhedral framework that consists of layers of corner-linked polyhedra. The SiO4 tetrahedra share corners to form 6-membered rings which are further interlinked via REEO6 trigonal prisms and Tiphi(6) octahedra (phi = O, OH). The obtained structure model is different from that recently reported by Rastsvetaeva et al. (2003) which is considered incorrect.

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