REFINEMENT OF CRYSTAL STRUCTURE OF BENITOITE BATI[SI3O9]

The crystal structure of benitoite has been refined on the basis of powder and single-crystal diffractometer data. Zachariasen's original structure has been fully confirmed. For the least-squares refinement, three-dimensional intensity data with I = 2n + 1 were used. Thus, the Si3O9 part of the structure could be refined with high accuracy neglecting the presence of heavy cations. The standard deviations of atomic distances were in the range of.002 to.004Å, those of bond angles were. 1 to. 5°. Anisotropic mean-square vibrational amplitudes were determined with a between 3 and 6 percent. With these results, a rough relative estimation of bindung forces could be obtained. The effect of thermal vibration on bond lengths, computed on a purely geometrical basis, has been demonstrated. © 1969, Walter de Gruyter. All rights reserved.