Measured oxygen fugacities of the Angra dos Reis achondrite as a function of temperature

Measurements of the oxygen fugacity (ƒO₂) as a function of temperature (T) were made on an interior bulk sample of the cumulate achondrite, Angra dos Reis. Data clustered between theƒO₂-T relationship of the iron-wüstite assemblage and 1.2 log atm units above iron-wüstite. Interpretation of the data indicates that, throughout most of the cooling history of the meteorite, ƒO₂ values were defined by equilibria involving iron-bearing species at values close to the ƒO₂ of the assemblage iron-wüstite. Measured ƒO₂ data are compatible with crystallization and cooling at pressures greater than 50 bars.