Comparison -For comparison of the previously given data, let us assume the central positions of the peaks (in cm -1 ), that we can observe in the spectra analyzed above, and given in the following table. For the spectrum provided by ROD, we propose the data as can be evaluated from the Fig. , but also the positions of the center of the bands as obtained by the best fit (fit in the Fig. , with four bands). In the table given above we can see the presence of the D band at about 1350 cm -1 (this band is negligible in RRUFF 050503 and 090047), of the G band at about 1580 cm -1 , and of the shoulder of this band at about 1610-1620 cm -1 (note please the different behavior of RRUFF 050503 and 090047 and the different position of the G peak shoulder). We can see that the carbonization of biochar graphitized it (according to . The presence of several elements, besides carbon, produces a band which appears between D and G bands (OSR1500); it seems something similar existing for OSR2200, but the component is so low and flat that we considered it negligible for comparison. In the case of ROD-3500021 we have this band, shifted towards the G band, so that we consider it as another shoulder of G peak (see Fig. ). As previously told, in the case of RRUFF 050503 and 090047 too, this band is a shoulder of the G band.