Determination of a probable reflexion symmetry by counting statistics shown in the example of the zeolite, NaP1

The deviation of symmetry equivalent intensities from their mean values was used to determine a probable reflexion symmetry for the zeolite NaPl. The method of investigation is based on the χ² test and compares the measured deviation with the one expected from counting statistics. The lattice dimensions of zeolite NaPl are cubic, but it was suspected that its symmetry is tetragonal and that the crystal is multiply twinned, thus simulating a near cubic X-ray pattern. Cubic symmetries were clearly rejected by the test and it was shown that reflexion symmetry mmm is a good approximation for the observed intensities.