The crystal structure of the rare feldspathoid trikalsilite has been solved and refined to R = 0.109, Rw = 0.096 for 565 unique reflections collected with Zr-filtered MoK-alpha. The last refinement cycles were carried out assuming the occurrence of minor twinning, and correspondingly correcting the measured intensities. Trikalsilite is hexagonal, space group P63, a = 15.339(4), c = 8.501(2) Å. The crystal structure of trikalsiltie is related to those of nepheline and tetrakalsilite, and is characterized by a three-dimensional framework of regularly alternating SiO4 and AlO4 tetrahedra. The cavities of the framework are filled with potassium and sodium cations; the occupancies in the alkaline sites were refined, thus obtaining Na0.33K0.67AlSiO4 as approximate chemical formula for trikalsilite.
|Autori:||BONACCORSI E; MERLINO S; PASERO M|
|Titolo:||Trikalsilite: Its structural relationships with nepheline and tetrakalsilite|
|Anno del prodotto:||1988|
|Appare nelle tipologie:||1.1 Articolo in rivista|