Let us consider the article entitled "Raman study of magnetite (Fe3O4): laser-induced thermal effects and oxidation", by . In it, we can find a study of natural magnetite (single crystal and powder) with the Raman spectroscopy at different laser powers. The laser power, if enough high, is inducing the oxidation of the sample (in the Appendix B, the phenomenon of the laser induced bandshift is illustrated for graphite). "In the course of the oxidation of the single crystal of magnetite, the first characteristic features of hematite appear at about 300 and 410 cm -1 , at a temperature close to 240 °C. This may explain the erroneous assignment of these modes to the intrinsic Raman modes of magnetite in some studies" . In the case of a finely powdered magnetite, we have a material which is "much more easily prone to oxidation". During the reaction mechanism, we find the "metastable maghemite (γ-Fe2O3) before the final product hematite is formed".