Add oxidized iron blocks too the game, similar to copper blocks and using the same gameplay features such as waxing (to retain the 'rust') and using anaxe (to strip one layer of 'rust'). This could be added in minecraft Caves and Cliffs part 2.
Please add Rust Dust, to strip one layer of 'rust' that release Rust Dust, Rust Dust cannot craft into Rust Block but can Oxidize from Iron Block. Can Brewed into Life potion as Hemoglobin.
Rust Dust into Rust Powder (not Rust Block). Rust Powder smelt into 2 Iron Nuggets.
https://www.curseforge.com/minecraft/mc-mods/rusted-iron heres a mod I found I think its what you wanted but Idk