A review of magnetite geochemistry of Chilean iron oxide-apatite (IOA) deposits and its implications for ore-forming processes

•Magnetite can be used as a tracer of the geological environment of ore formation and as a fingerprint of the source reservoir of iron.•The formation and evolution of IOAs deposits can be assessed using compatible trace elements in magnetite such as Al, Ti, V, Cr, Mn, Ni, Cu and Ga.•Chilean IOA deposits formed at different conditions ranging from high-temperature purely magmatic, to magmatic-hydrothermal, to low-temperature hydrothermal conditions.•Magnetite is susceptible to multiple microtextural and compositional re-equilibrium events during the formation and evolution of IOA deposits.•The flotation model as a basal transfer mechanism of Fe allows variations and the definition of different subtypes of IOA mineralization, controlled by the depth of formation, structures/faults, composition of the host rock, the source of hydrothermal fluids and the fluid/rock ratio.