chemical remanent magnetization

Chemical remanent magnetization (CRM) is a type of permanent magnetism that rocks and minerals can retain after an external magnetic field is removed. This magnetization is induced after a crystal has formed and undergoes physicochemical changes, such as oxidation, reduction, dehydration, or recrystallization. CRM is particularly significant in some red sediments and metamorphic rocks and typically occurs at constant temperatures within Earth's magnetic field. This process is distinct from other forms of remanent magnetization, such as thermoremanent magnetization (TRM), which occurs when magnetic minerals cool through their Curie temperature, or detrital remanent magnetization (DRM), acquired by magnetic grains settling in sediments.12