Fig. The red line is giving the RRUFF data R050209. The fitted green line is the sum of the q-BWF components of spectrum decomposition. To fit the data given in the upper panel of the Figure , we used 8 q-BWF functions. Here we show only the part of the spectrum from 340 to 450 cm -1 . In the lower panel, just the two main components are given; the blue and the magenta lines have q(blue)=1.60 and q(magenta)=1.50. In the middle, the resulting misfit is proposed. The misfit is the difference between data (red) and the fitted curve (green).