Abstract
The crystal structure of jimboite, Mn3(BO3)2, was determined with the aid of three-dimensional least squares and Fourier syntheses. It consists of BO3-groups and octahedral coordinations of oxygen ions around manganese ions and is almost strictly isostructural with kotoite, in spite of the difference in size between manganese and magnesium ions. In these structures, compact BO3-groups are almost solely responsible for the deviations in the array of oxygen ions from hexagonal closest-packing, and accordingly the effect of the difference in size of the cations upon the structures is obscured.
