High pressure phase transformation of jadeite and stability of NaAlSiO4 with calcium-ferrite type structure in the lower mantle conditions

Phase transformation of jadeite clinopyroxene was studied at temperatures o f 800 and 2200 degrees C at pressures between 30-75 GPa in externally elect rically heated and internally laser-heated diamond anvil cells. It has been found that jadeite transforms to the assemblage of NaAlSiO4 (calcium-ferri te type structure) plus stishovite at high pressure and temperatures. There fore NaAlSiO4 calcium-ferrite is stable at the deep lower mantle pressure a nd temperature conditions.