Keywords:FeAlO3 phase, sillimanite, corundum, spinel, ultrahigh-temperature granulies
Two high pressure experiments at 9 kbar and 1050 ℃ under moisture condition reveal FeAlO3 phase is stable under ultrahigh-temperature metamorphic conditions. FeAlO3 and corundum newly crystallised accompanying SiO2-rich melt and vapour among sillimanite crystals from the mixture of Rundvågshetta sillimanite and reagent-grade Fe2O3 (weight ratio of 95:5) within Pt capsule. We found no hematite in the charge. In contrast, we found FeAlO3 phase, SiO2-rich melt and vapour among sillimanite from the mixture of Rundvågshetta sillimanite and reagent-grade Fe3O4 at (weight ratio of 86:14) within AuPd capsule. We found a domain composed by FeAlO3, corundum, magnetite—hercynite spinel and ulvöspinel at the bottom part of the charge. The domain was contact with melt among sillimanite. The present results suggest the possibility that FeAlO3 phase would be an index mineral of ultrahigh-temperature metamorphism for the partially melted Fe—Al-rich granulites under hydrous and oxidised environments.