Almandine and titanomagnetite and hercynite oxides as indicators of oxygen fugacity in rocks

Thermodynamic properties of Fe-Al garnet (almandine) and Fe-Ti (Titanomagnetite) and Fe-Al (hercynite) spinels have been determined. The free energy of the reaction between almandine, sillimanite, iron, and quartz was measured electrochemically at 1 atm and is in good agreement with values determined from high pressure phase equilibria. The presence of Fe;The low ;The activity of Fe...