The absence of oxide mixture in high‐pressure phases of Mg‐silicates

High pressure phase relations of MgSiO3 and Mg2SiO4 have been studied up to pressures higher than 300 kbar, using a double‐stage split‐sphere apparatus. It has been confirmed that the ilmenite phase of MgSiO3 and γ‐Mg2SiO4 transform directly at about 300 kbar to the orthorhombic perovskite phase and the assemblage of MgSiO3 perovskite plus MgO periclase, respectively. These results are consistent with those by Liu [1976 a and b] but do not support the stability of oxide mixture (periclase plus stishovite) claimed by Kumazawa et al. [1974] and Ming and Bassett [1975 a and b].