The redetermination and refinement of the crystal structure of rhodonite, (Mn,Ca)SiO3

Abstract

Rhodonite has space group PI and unit-cell parameters a = 7.682 A, b = 11.818A, c = 6.707 A, 0< = 92.355°, f3 = 93.948°, and y = 105.665°. A trial structure determined through application of the minimum function to the Patterson function, P(xyz), was improved and refined with Fourier syn- theses and least squares. Planes containing octahedrally coordinated cations alternate with planes of tetrahedrally coordinated Si ions between planes of approximately close- packed oxygen ions. Tetrahedra are linked to form chains with a repeat unit