Reports

The Postspinel Phases in the Mg2SiO4-Fe2SiO4 System

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Science  10 Jan 1975:
Vol. 187, Issue 4171, pp. 66-68
DOI: 10.1126/science.187.4171.66

Abstract

Samples of olivine (Fo0Fa100, Fo60Fa40, Fo80Fa20, and Fo100Fa0) and of spinel (Fo50Fa50, Fo2Fa100, where Fo is forsterite and Fa is fayalite) were subjected to pressures up to 250 kilobars in a diamond anvil press and were heated in situ up to ~ 1700°C by an infrared beam from a continuous-wave YAG (yttrium-aluminum-garnet) laser. The brightness temperature was determined from the intensity of incandescence of the sample by means of an optical pyrometer. X-ray diffraction patterns of the samples, obtained after quenching and unloading, show conclusively that these compositions disproportionate to (Mg, Fe)O and SiOs (stishovite) under these conditions.