Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (11) Citing Articles via Google Scholar Google Scholar Articles by Hovis, G. L. Articles by Rodrigues, E. Search for Related Content GeoRef GeoRef Citation

Thermodynamic and structural behavior of analcime–leucite analogue systems

¹ Department of Geology and Environmental Geosciences, Lafayette College, Easton, Pennsylvania 18042, U.S.A.
² ISTO, CNRS-Université d’Orléans, 1A, rue de la Férollerie, 45071 Orléans cedex 2, France
³ UFPA–CCEN, Departamento de Química, Rua Augusto Correa no. 1, 66.075-110, Belém, Pará, Brazil

Correspondence: ^* E-mail: hovisguy{at}lafayette.edu

Two synthetic solid-solution series, analcime to Rb-leucite and analcime to Cs-leucite (pollucite), have been investigated to understand more fully the thermodynamic and structural behavior of analcime-leucite and similar mineral systems. Unit-cell dimensions and volumes in these series expand with the substitution of analcime component in either Rb-leucite or pollucite, as H₂O molecules structurally replace the smaller entities Rb⁺¹ or Cs⁺¹, respectively. Unit-cell volumes vary linearly as functions of composition, but with changing slopes over several segments of compositional space, akin to thermal expansion in K-, Rb-, and Cs-end-member materials studied by previous workers. When symmetry changes displacively from tetragonal to isometric, as in the Rb-bearing series, the slope of volume expansion changes. Once structures have reached full expansion, volume slopes flatten and are little affected by additional analcime component. Enthalpies of solution measured at 50 °C in 20.1 wt% hydrofluoric acid show single-slope linear relationships over the entire compositional ranges of both series. Thus, despite positive volumes of mixing, there are no enthalpies of mixing in either series, nor is there energetic evidence of displacive tetragonal/isometric inversion or the various stages of structural expansion. Overall, the data suggest that the analcime–leucite system also can be modeled as close to thermodynamically ideal. The limited solid solution between natural analcime and leucite must be attributed to energetically favored heterogeneous equilibria involving minerals such as feldspars and other feldspathoids, and not to immiscibility between the end-members.

This article has been cited by other articles:

				G. L. Hovis and J. Roux Thermodynamic mixing properties of Rb-K feldspars American Mineralogist, October 1, 2008; 93(10): 1597 - 1602. [Abstract] [Full Text] [PDF]

				P. S. Neuhoff and J. Wang Heat capacity of hydration in zeolites American Mineralogist, August 1, 2007; 92(8-9): 1358 - 1367. [Abstract] [Full Text] [PDF]

				R. W. Luth and M. Bowerman MICROTEXTURAL AND POWDER-DIFFRACTION STUDY OF ANALCIME PHENOCRYSTS IN VOLCANIC ROCKS OF THE CROWSNEST FORMATION, SOUTHERN ALBERTA, CANADA Can Mineral, June 1, 2004; 42(3): 897 - 903. [Abstract] [Full Text] [PDF]

				P. S. Neuhoff, G. L. Hovis, G. Balassone, and J. F. Stebbins Thermodynamic properties of analcime solid solutions Am J Sci, January 1, 2004; 304(1): 21 - 66. [Abstract] [Full Text] [PDF]

				P. S. Neuhoff, P. S. Neuhoff, J. F. Stebbins, and D. K. Bird Si-Al disorder and solid solutions in analcime, chabazite, and wairakite American Mineralogist, February 1, 2003; 88(2-3): 410 - 423. [Abstract] [Full Text] [PDF]