Abstract
Crystals of ferrian aluminian diopside were synthesized and the structures were investigated by means of a single-crystal X-ray diffraction method in detail. EPMA gave the chemical formula of Ca1.00(Mg0.55Fe3+0.37Al0.08)(Si1.55Al0.45)O6 for the crystals as an average. Structure refinement indicated that about 9 % of Fe3+ ions are at T sites, giving the formula of Ca1.00(Mg0.55Fe3+0.34Al0.11)(Si1.55Al0.42Fe3+0.03)O6. Existence of Fe3+ at T sites was, however, not confirmed on a difference Fourier map synthesized by making use of anomalous dispersion effect at the Fe K absorption edge. The bond distances are reasonable for a ferrian aluminian diopside with a chemical composition found for the present crystals.
