Contributions to Mineralogy and Petrology

, Volume 160, Issue 3, pp 327–337 | Cite as

A ternary feldspar-mixing model based on calorimetric data: development and application

  • Artur BenisekEmail author
  • Edgar Dachs
  • Herbert Kroll
Original Paper


A mixing model for high structural state ternary feldspars in the NaAlSi3O8–KAlSi3O8–CaAl2Si2O8 system is presented based exclusively on calorimetric and volumetric measurements. Comparisons with existing mixing models, which are based on phase-equilibrium experiments, reveal distinct differences. The incorporation of K into Ca-rich plagioclase and of Ca into K-rich alkali feldspar is more strongly limited by our calorimetry-based model, whereas the stability field of Na-rich feldspars is broadened. Natural feldspar assemblages from well-studied magmatic and high-grade metamorphic rocks (i.e. a teschenite sill in Scotland, the Klokken syenogabbro in Greenland, and a granulite-facies metapelite in Sri Lanka) were used to test the mixing models. It was found that the new model largely eliminates discrepancies between observed and predicted feldspar compositions that were present in earlier attempts. The reasons for the problems associated with phase-equilibrium based mixing models are discussed.


Thermodynamics Calorimetry Mixing model Ternary system Feldspar Thermometry 



This work was supported by a grant from the Austrian Science Fund, project number P 20210-N10, which is gratefully acknowledged. We thank N. S. Rahmoun, Kiel, for collecting the IR spectra and P. Raase, Kiel, for providing the thin sections and for valuable discussions. We also thank R. Abart, Wien, for his valuable contributions. The manuscript benefited much from a careful and constructive review by I. Parsons, Edinburgh.

Supplementary material

410_2009_480_MOESM1_ESM.pdf (43 kb)
Supplementary material 1 (PDF 42 kb)
410_2009_480_MOESM2_ESM.pdf (75 kb)
Supplementary material 2 (PDF 74 kb)
410_2009_480_MOESM3_ESM.pdf (20 kb)
Supplementary material 3 (PDF 19 kb)


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Copyright information

© Springer-Verlag 2010

Authors and Affiliations

  1. 1.Fachbereich Materialforschung und PhysikUniversität SalzburgSalzburgAustria
  2. 2.Institut für MineralogieWestfälische Wilhelms-UniversitätMünsterGermany

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