The Crystal Structure of Quartz

Crystal structure of quartz.—Photographs by the powder method of X-ray crystal analvsis have confirmed the space-lattice proposed by others. A careful study of 30 possible arrangements has shown that the arrangement of atoms which best fits the observed intensities of the lines in the pattern differs somewhat from those previously proposed, maintaining more clearly the identity of the molecule Si${\mathrm{O}}_2$. These molecules are obtuse-angled isosceles triangles (angle at Si atom-center, 115° 14′; distance between Si and O atom-centers, 1.631 × ${10}^{-8\mathrm{}}$ cm) lying in the basal planes of each of three interpenetrating hexagonal space-lattices, so that the crystal may be considered as built up of layērs of molecules, much closer together than adjacent molecules in the same layer.