Red rust identification

Thank you! So just to clarify, I have Fe2O3 (hematite) attached to a surface and I used iron or a magnet, it will not happen anything? Compare to having Fe3O4 attached to a surface (in which iron will be attracted? )

I have use an etchant to tell if a part is rusted, but this etchant reacts for both fe2O and fe3O4. I was mostly looking for a method to truly tell when we have one or the other.

Does someone know about a chemical procedure to differentiate these phases? If not chemical, do you have another?