We may attempt here an explanation for the mechanism of pseudo-brookite Fe2TiO5 formation, even though a proper structural in situ investigation was not conducted during this study. We start our explanation following the same arguments developed elsewhere, hypothesizing the existence of two kinds of Ti bonds in the bulk of the akaganeite iron oxyhydroxide structure formed after the ACG process. One is substituting Fe in Fe-O6 octahedra and the other is bonded with the Cl from the akaganeite tunnel structure.