Iron cycle
"The iron cycle is the biogeochemical cycle that couples the oxidation and reduction reactions of iron, a key element for life" (Amils 2011)
Sources
Amils R. (2011) "Iron Cycle". Gargaud M. et al. (eds) Encyclopedia of Astrobiology. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-11274-4_810