Experimental determination of activities in Fe-Mg olivine at 1400 K

Nathan M. Wiser*, Bernard J. Wood

*Corresponding author for this work

    Research output: Contribution to journalArticle

    71 Citations (Scopus)

    Abstract

    The exchage equilibrium {Mathematical expression} has been used to measure activity-composition relations along the olivine join FeSi0.5O2-MgSi0.5O2 at 1400 K and 1 atm pressure. Equilibrium Fe-Mg partitioning between the two phases was determined by reversing the compositions of olivine coexisting with oxide and matallic iron over the composition range Fo23 to Fo92. A detailed study of the thermodynamic properties of the oxide phase has recently been made by Srečec et al. and we have confirmed their results in the composition range of interest. Application of the oxide data to the exchange equilibrium enables the properties of olivine to be determined. Within experimental uncertainly (Fe, Mg)Si0.5O2 olivine can, at 1400 K, be treated as a symmetric solution with WFe-Mgo1 of 3.7±0.8 kJ/mol. The data permit the presence of only very slight asymmetry in the series. The data do not support recent assertions that olivine is highly non-ideal (W≈10 kJ/mol) under these conditions.

    Original languageEnglish
    Pages (from-to)146-153
    Number of pages8
    JournalContributions to Mineralogy and Petrology
    Volume108
    Issue number1-2
    DOIs
    Publication statusPublished - Jul 1991

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