Noun
a red oxide of iron
Source: WordNetFlexible magnets are composed of a high- coercivity ferromagnetic compound (usually ferric oxide ) mixed with a plastic binder. citation This is extruded as a sheet and passed over a line of powerful cylindrical permanent magnets. Source: Internet
For such iron-rich rocks to be deposited there would have to be anoxia in the ocean, so that much dissolved iron (as ferrous oxide ) could accumulate before it met an oxidant that would precipitate it as ferric oxide. Source: Internet