**3. Conclusions**

Iron oxides are not the only minerals formed by recrystallization processes. However, their abundance, small crystallite size, quick formation patterns that often involve preservation of their precursor enables their observation through various electron microscopes of the mor‐ phology or impurities from the precursor.

In this chapter it was shown that the initial morphology of ferrihydrite is preserved in re‐ crystallization into more stable phases like goethite, akaganéite and hematite. It was also shown that hematite can be formed through several recrystallization processes from other iron oxides or iron bearing minerals.

In some cases, slow recrystallization process is captured within the sample leading to obser‐ vation both the decomposing precursor and the newly formed product. For example trans‐ formation of singerite into nontronite clay mineral or ilmenite into hematite.
