Distribution of titanium atoms in oxy-kaersutite

The distribution of Ti atoms in oxy-kaersutite has been studied by the neutron diffraction method. The cation distribution over the three octahedral sites determined by the x-ray method (Kitamura and Tokonami, 1971) is as follows; M1∶0.40MG+0.60 FE, M2∶0.75 MG+0.25 FE, M3∶0.50 MG+0.50 FE, where MG and FE represent (Mg+Al) and (Fe+Ti), respectively. The neutron diffraction study indicates that Ti atoms are enriched in the M1 site more than M2 and M3 sites as follows; M1∶0.40 MG+0.33 Fe+0.27 Ti, M2∶ 0.75 MG+0.23 Fe+0.02 Ti, M3∶0.50 MG+0.46 Fe+0.04 Ti. This distribution agrees with the result based on the Madelung energy of oxy-kaersutite by Whittaker (1972).