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Twinning in an orthorhombic aluminate sodalite, Ca8[Al12O24] (CrO4)2

Published online by Cambridge University Press:  05 July 2018

Ishmael Hassan
Ishmael Hassan*
Affiliation:
Department of Geology, Faculty of Science, University of Kuwait P.O. Box 5969, Safat, Kuwait 13060
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Abstract

Transmission electron microscopy (TEM) was used to study the aluminate sodalite, Ca8[Al12O24](CrO4)2. This aluminate sodalite has four polymorphs: one cubic, one modulated, one tetragonal, and an orthorhombic cell that arise from ordering of [Ca4·CrO4]6+ clusters that occur in the cages of the structure. The transition temperatures are 432, 453, and 610 K. The cell parameters for the orthorhombic phase, with the cubic cell parameter of a = b = c = 9.222 Å, are 3a × 2b × c. Transformation twins are formed at 432 K during the transition from the tetragonal to the orthorhombic phase. The twin plane is {110} in the cubic cell, and {320} in the orthorhombic cell.

Keywords

aluminate sodalitetwinningsodalite groupnoseanhaüynelazuriteTEMsuperstructures
Type
Mineralogy
Information
Mineralogical Magazine , Volume 60 , Issue 401 , August 1996 , pp. 617 - 622
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1996

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References

Depmeier, W. (1984) Aluminate sodalite Ca8[Al12O24](WO4)2 at room temperature. Acta Crystallogr., C40, 226—31.Google Scholar
Depmeier, W. (1988a) Aluminate sodalites — a family with strained structure and ferroic phase transitions. Phys. Chem. Minerals, 15, 419–26.CrossRefGoogle Scholar
Depmeier, W. (1988b) Structure of cubic aluminate sodalite Ca8[Al12O24](WO4)2 in comparison with its orthorhombic phase and with cubic Sr8[Al12O24](CrO4)2. Acta Crystallogr.y B44, 201-7.CrossRefGoogle Scholar
Depmeier, W., Schmid, H., Setter, N. and Werk, M.L. (1987) Structure of cubic aluminate sodalite Sr8[Al12O24](CrO4)2. Acta Crystallogr. C43, 2251-5.Google Scholar
Hassan, I. (1994) The crystal chemistry of the feldspathoids and their relationship to the zeolites. IMA Abstracts with Program. Pisa, Italy, 16, 695.Google Scholar
Hassan, I. and Buseck, P.R. (1988) A HRTEM characterization of scapolite solid-solutions. Amer. Mineral, 73, 119–34.Google Scholar
Hassan, I. and Buseck, P.R. (1989a) Incommensurate-modulated structure of nosean, a sodalite-group mineral. Amer. Mineral., 74, 394–410.Google Scholar
Hassan, I. and Buseck, P.R. (1989b) Cluster ordering and antiphase domain boudaries in hauyne. Canad. Mineral., 27, 173–80.Google Scholar
Hassan, I. and Grundy, H.D. (1983) Structure of basic sodalite, Na8Al6Si6O24(OH)22H2O. Acra Crystallogr, C39, 3–5.Google Scholar
Hassan, I. and Grundy, H.D. (1984) The crystal structures of sodalite-group minerals. Acta Crystallogr. B40, 6—13.Google Scholar
Hassan, I. and Grundy, H.D. (1985) The crystal structure of helvite group minerals, (Mn,Fe,Zn)8 (Be6Si6O24)S2- Amer. Mineral 70, 186—92.Google Scholar
Hassan, I. and Grundy, H.D. (1989) The structure of nosean, ideally Na8[Al6Si6O24]SO4-H2O. Canad. Mineral 27, 165-72.Google Scholar
Hassan, I. and Grundy, H.D. (1991a) The crustal structure of hauyne at 293 and 153 K. Canad. Mineral. 29, 123—30.Google Scholar
Hassan, I. and Grundy, H.D. (1991b) The crystal structure and thermal expansion of tugtupite, Na8(Al2Be2Si8O24)Cl2. Canad. Minera., 29, 385-90.Google Scholar
Hassan, I., Peterson, R.C. and Grundy, H.D. (1985) The structure of lazurite, ideally Na6Ca2(Al6Si6O24)S2, a member of the sodalite group. Acta Crystallogr. C41, 827-32.Google Scholar
Saalfeld, H. (1961) Strukturbesonderheiten des Hauyngitters. Z Krist., 115, 132—40.CrossRefGoogle Scholar
Schulz, H. (1970) Struktur und Uberstukturunter-suchun- gen an Nosean-Einkristallen. Z Krist., 131, 114–38.CrossRefGoogle Scholar
Taylor, D. (1967) The sodalite group of minerals. Contrib. Mineral. Petrol., 16, 172–88.CrossRefGoogle Scholar
Tsichiya, N. and Takeuchi, Y. (1985) Fine texture of hauyne having a modulated structure. Z. Krist. 173, 273-81.CrossRefGoogle Scholar
Xu, H. and Veblen, D.R. (1995) Transmission electron microscopy study of optically anisotropic and isotropic hauyne. Amer. Mineral. 80, 87—93.Google Scholar