The Postspinel Phases in the Mg2SiO4-Fe2SiO4 System.
Samples of olivine (Fo(0)Fa(100), Fo(60)Fa(40), Fo(80)Fa(20), and Fo(100)Fa(0)) and of spinel (Fo(50)Fa(50), Fo(2)Fa(100), 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 degrees 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 SiO(s) (stishovite) under these conditions.
Ming
L C
LC
Bassett
W A
WA