Although the studied crystals of stilbite, from Poona, (India), are ch
emically homogeneous, the {001} growth sector is orthorhombic with reg
ard to X-rays, whereas the {101} sector is monoclinic. The {001} secto
r of stilbite is isomorphous with stellerite. The symmetry of the orth
orhombic {001} sector of stilbite is explained by the rotation of Si t
etrahedra during crystal growth.