High-Pressure and High-Temperature in situ X-ray Diffraction Study of Natural Garnet(Mg_<0.72>Fe_<0.17>Ca_<0.11>)_3Al_2Si_3O_<12> up to 32 GPa and 2000 K Using MA8-Type Apparatus
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Breakdown reaction of natural garnet was studied by an in situ x-ray observation using an MA8-type multi-anvil apparatus up to about 32 GPa. Natural garnet with a composition (Mg<SUB>0. 72</SUB>Fe<SUB>0. l7</SUB>Ca<SUB>0. 11</SUB>) <SUB>3</SUB>Al<SUB>2</SUB>Si<SUB>3</SUB>O<SUB>12</SUB> breaks down at a pressure between 24 and 27 GPa to a mixture of sub-aluminous orthorhombic silicate perovskite, stishovite, Al-rich phase with unknown structure, and possibly CaSiO<SUB>3</SUB> perovskite. The unreacted garnet was observed even after heating the sample at 31. 7 GPa and 2000 K for 6000 sec. This result implies that the transition rate of the garnet is lower than that of Al-free system such as olivine and pyroxene.
- The Review of High Pressure Science and Technology
The Review of High Pressure Science and Technology 7, 59-61, 1998
The Japan Society of High Pressure Science and Technology