Why are the common magnets black

In fact, ordinary micromagnetism (or weak magnetism) is made up of ferrous metals (usually iron and its compounds), so it is black.




However, if it is strong magnetic, it is composed of rare earth metals such as cobalt, boron, europium, iridium and other compounds. So it's all white.




The common magnet material is Fe3O4 and Fe3O4 is black, so the common magnet is black.