High temperature crystal chemistry of fayalite1

The crystal structure of a pure synthetic fayalite has been refined from three dimensional X-ray intensity data measured at 20°, 300°, 600°, and 900°C. Cell dimensions have been determined at 20°, 300°, 450°, 600°, 750°, and 900°C. Comparison of the structures with those of other Mg-Fe olivines is consistent with a slight preference of Fe for the smaller but more distorted M1 site. With increasing temperature, the M1-O and M2-O distances tend to become more regular while the central bond angles of the octahedra show increasing distortion.