Experimental investigation of andradite and hedenbergite equilibria employing the hydrogen sensor technique, with revised estimates of ΔfG0 m,298 for andradite and hedenbergite

D. P. Moecher, I. M. Chou

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21 Scopus citations

Abstract

Hydrothermal experiments were carried out at 2 kbar, 600-860°C to resolve discrepancies among previous studies on fO2-T stability relations for the following equilibria: 1) andradite (And) = hematite (Hm) + wollastonite (Wo), 2) And = magnetite (Mt) + Wo + O2, 3) And + quartz (Qz) = hedenbergite (Hd) + Wo + O2, and 4) And + Mt + Qz = Hd + O2. A variety of O buffer and H2 generation techniques were used to access a wide range of fO2-T conditions. The results yielded an internally consistent set of experiments on andradite and hedenbergite stability. The ΔfG0 m,298 for andradite and hedenbergite calculated from the data are -5428.0 ± 5.9 and =2676.6 ± 5.3 kJ/mol, respectively. -from Authors

Original languageEnglish
Pages (from-to)1327-1341
Number of pages15
JournalAmerican Mineralogist
Volume75
Issue number11-12
StatePublished - 1990

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology

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