Hostname: page-component-78c5997874-lj6df Total loading time: 0 Render date: 2024-11-19T05:38:39.946Z Has data issue: false hasContentIssue false
  • English
  • Français

Thermal expansion of cancrinite

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, 13060, Kuwait
Get access Rights & Permissions [Opens in a new window]

Abstract

Thermal expansion coefficients were measured for a cancrinite from Bancroft, Ontario, Canada. Measurements of cell parameters and unit-cell volumes were obtained at room temperature and at heating intervals of 50°C over the temperature range from 50 to 1400°C. The unit-cell parameters for cancrinite increase non-linearly with temperature up to 1200°C and shortly thereafter, the mineral melted. The c parameter increases more rapidly than the a parameter, and the c/a ratio increases linearly with temperature. A plausible thermal expansion mechanism for cancrinite, which is based on the framework expansion that occurs as a function of cavity content, is presented. In the thermal expansion of cancrinite, the short Na-H2O in the H2O-Na—H2O chain expands to form equal distances to the two H2O molecules in the chain. This causes the Na atoms to move towards the plane of the six-membered rings and forces the tetrahedra to rotate and the rings become more planar. The Na atoms then form bonds to all six (O1 and O2) oxygen atoms in a ring; the Na-O1 bonds become shorter and the Na-O2 bonds become longer. These effects cause an increase in both a and c, and thus an increase in the c/a ratio. A similar thermal expansion mechanism operates in the sodalite-group minerals where the six-membered rings and Na-Cl bond are involved.

Keywords

cancrinitecancrinite-groupthermal expansionpowder X-Ray diffraction
Type
Mineralogy
Information
Mineralogical Magazine , Volume 60 , Issue 403 , December 1996 , pp. 949 - 956
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1996

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Bonaccorsi, E., Merlino, S. and Pasero, M. (1990) Davyne: its structural relationships with cancrinite and vishnevite. Neues Jahrb. Mineral. Mh., 3, 97–112.Google Scholar
Bonaccorsi, E., Merlino, S., Orlandi, P., Pasero, M. and Vezzalini, G. (1994) Quadridavy ne, [(Na, K)6Cl2][Ca2Cl2][Al6Si6O24]I2, a new feld- spathoid mineral from Vesuvius area. Eur. J. Mineral., 6, 481—7.Google Scholar
Demsey, M.J. and Taylor, D. (1980) Distance least squares modelling of the cubic sodalite structure and the thermal expansion of Nag[Al6Si6O24]I2. Phys. Chem. Mineral., 6, 197–208.CrossRefGoogle Scholar
Grundy, H.D. and Hassan, I. (1982) The crystal structure of a carbonate-rich cancrinite. Canad. Mineral, 20, 239–51.Google Scholar
Hassan, I. (1996) The thermal behaviour of cancrinite. Canad. Mineral., 34 (in press).Google Scholar
Hassan, I. and Grundy, H.D. (1984a) The crystal structures of sodalite-group minerals. Acta Crystallogr. B40, 6–13.Google Scholar
Hassan, I. and Grundy, H.D. (1984b) The character of the cancrinite-vishnevite solid-solution series. Canad. Mineral., 22, 333–40.Google Scholar
Hassan, I. and Grundy, H.D. (1990) The structure of davyne and implications for stacking faults. Canad. Mineral., 28, 341–9.Google Scholar
Hassan, I. and Grundy, H.D. (1991a) The crystal structure and thermal expansion of tugtupite, Na8[Al2Be2Si8O24]Cl2. Canad. Mineral, 29, 385–90.Google Scholar
Hassan, I. and Grundy, H.D. (1991b) The crystal structure of basic cancrinite, ideally Na8[Al6Si6O24]-3H2O. Canad. Mineral., 29, 377–84.Google Scholar
Henderson, C.M.B. and Taylor, D. (1978) The thermal expansion of synthetic aluminosilicate-sodalites, M8[Al6Si6O24]X2. Phys. Chem. Mineral., 2, 337–47.CrossRefGoogle Scholar
Merlino, S. (1984) Feldspathoids: their average and real structures. NATO ASI Ct 137, 435-70.Google Scholar
Merlino, S., Mellini, M., Bonaccorsi, E., Pasero, M., Leoni, L. and Orlandi, P. (1991) Pitiglianoite, a new feldspathoid from southern Tuscany, Italy: chemical composition and crystal structure. Amer. Mineral., 76, 2003–8.Google Scholar
Peacor, D.R., Rouse, R.C., and Ahn, J-H. (1987) Crystal structure of tiptopite, a framework beryllophosphate isotypic with basic cancrinite. Amer. Mineral., 72, 816–20.Google Scholar