The crystal structure of Kotoite (Mg3B2O6), a new mineral found from Suan Mine, Korea by T. Watanabe, has been determined by X-ray methods using oscillation and Weissenberg photographs (Co-Ka) and the ionization spectrometer (Mo-Ka) . The space group is D122h-Pnmn, (hk0) and (0kl) reflexions beiog absent respectively when h+k and k+l are odd. The unit cell has the dimensions a=5.335A, b=8.400 A and c=4.487 A. There are two molecules of Mg3B2O6 (sp. gr. 3.11.) .
Closelyy resembling the olivine group, the structure is based fundamentally on the hexagonal closest packing of oxygen atoms. Each B atom is at the center of a triangle formed by three oxygen atoms and each Mg atom is surrounded by eight oxygen atoms arranged nearly octakedrally. Each oxygen atom is shared by three Mg and one B atoms.
