The inverse-spinel ferrimagnet has a Curie temperature of 580 °C; naturally magnetized lodestone is how ancient peoples first discovered magnetism.
In the 1930s the German Magnetophon tape recorder used magnetite powder that BASF coated onto cellulose acetate, until 3M replaced it with needle-shaped gamma ferric oxide in 1946.
Kirschvink et al. reported magnetite biomineralization in the human brain in 1992, and magnetotactic bacteria navigate with chains of magnetite magnetosomes.