Dear Saibal,
It depends whether you are interested in K-Na or (K,Na)Al-Si exchange.
These references should help you:
Hovis, Guy L.; Crelling, James A. The effects of excess silicon on
immiscibility in the nepheline-kalsilite system. American Journal of
Science (2000), 300(3), 238-249.
Hovis, Guy L.; Roux, Jacques. Thermodynamics of excess silicon in
nepheline and kalsilite crystalline solutions. European Journal of
Mineralogy (1999), 11(5), 815-827.
Hovis, Guy L.; Roux, Jacques. Thermodynamic mixing properties of
nepheline-kalsilite crystalline solutions. American Journal of
Science (1993), 293(10), 1108-27.
Sack, Richard O.; Ghiorso, Mark S. Thermodynamics of feldspathoid
solutions. Contributions to Mineralogy and Petrology (1998),
130(3-4), 256-274.
Ferry, John M.; Blencoe, James G. Subsolidus phase relations in the
nepheline-kalsilite system at 0.5, 2.0, and 5.0 kbar. American
Mineralogist (1978), 63(11-12), 1225-40.
I believe that Sack-Ghiorso's formulation is also incorporated in the
Melts software,
David
[log in to unmask] wrote:
> Hi,
>
> Could someone please help with information on activity models for
> nepheline? Can't seem to find any reference that talks about this. And
> yet, I think nepheline is on the THERMOCALC program, but not on AX.
>
> Saibal Gupta.
>
>
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David Dolejs (postdoc/geochemistry)
Bayerisches Geoinstitut
Universitaet Bayreuth
D-95440 Bayreuth Tel: +49 921 553717
Germany Fax: +49 921 553769
http://www.users.bgi.uni-bayreuth.de/~d_dolejs/
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