Enthalpy of formation of siderite and its application in phase equilibrium calculation

Chai Liang Chai, A. Navrotsky

Research output: Contribution to journalArticlepeer-review

34 Scopus citations

Abstract

The enthalpy of formation of siderite at 298 K has been determined from transposed temperature drop calorimetric measurements of enthalpies of decomposition of siderite at both 978 and 1075 K in an O2 atmosphere. Enthalpy of formation values from the experimental enthalpies at 978 and 1075 K are consistent, and the final result is ΔH0 f,298 = -750.6 ± 1.1 kJ/mol. The enthalpy of formation of siderite has been used to calculate the univariant curve for the equilibrium: siderite + hematite = magnetite + CO2. This curve lies about 100°C lower than that calculated using thermodynamic data from literature and about 70°C lower than the recent reversal at 10 kbar of Koziol and Newton (1993). Some possible reasons for these discrepancies are discussed, and the thermodynamic data for phases in this system are reevaluated. -from Authors

Original languageEnglish (US)
Pages (from-to)921-929
Number of pages9
JournalAmerican Mineralogist
Volume79
Issue number9-10
StatePublished - 1994
Externally publishedYes

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology

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