RRUFF allows us to examine the data in the following manner too. We can use the plot given by the site and look at the data having the high intensity values. Let us consider the possibility (Fig. ) of two "undulations" at 514.3 and 521.3 cm -1 to identify the components' centres. The consequent fitting, constrained to these positions, is given in the Fig. . The misfit that we find has lower values. Another case is given in the Fig. , with an even lower misfit too.