Promotes the biosynthesis of heme and assembly and repair of iron-sulfur clusters by delivering Fe(2+) to proteins involved in these pathways. May play a role in the protection against iron-catalyzed oxidative stress through its ability to catalyze the oxidation of Fe(2+) to Fe(3+); the oligomeric form but not the monomeric form has in vitro ferroxidase activity. May be able to store large amounts of iron in the form of a ferrihydrite mineral by oligomerization. Modulates the RNA-binding activity of ACO1 (By similarity). 4 Fe(2+) + 4 H(+) + O2 = 4 Fe(3+) + 2 H2O Monomer (probable predominant form). Oligomer. Interacts with LYRM4 and HSPA9. Interacts with ACO1. Interacts with ISCU. Interacts with FECH; one iron-bound FXN monomer seems to interact with a FECH homodimer. Interacts with SDHA and SDHB. Interacts with ACO2; the interaction is dependent on citrate. Processed in two steps by mitochondrial processing peptidase (MPP). MPP first cleaves the precursor to intermediate form and subsequently converts the intermediate to yield frataxin mature form (By similarity). Belongs to the frataxin family.