Die Verfeinerung der Kristallstruktur eines metamorphen Orthopyroxens

The atomic coordinates, the isotropic temperature factors and the site-occupancy factors of a metamorphic orthopyroxene Mg_1,56Fe_0,39Ca_0,05Si₂O₆ have been refined by the least-squares method using 1373 crystallographically independent reflections. Three-dimensional intensity data have been determined by integrated Weissenberg photographs. The final residual is 0.11. The site-occupancy factors M 1 = Mg_0,968 + Fe_0,032 and M 2 = Mg_0,589 + Fe_0,361 + Ca_0,050 reflect a high degree of order in the intracrystalline Mg, Fe distribution. The M 1, M 2 octahedra, the Si tetrahedra and the dependence of the means interatomic distances M  O on the Mg. Fe site occupancy are the subject of discussions.