What is the parent rock of phyllite?

Phyllite is a metamorphic rock that forms from the parent rock shale or mudstone through low-grade metamorphism. During this process, the minerals in the original rock recrystallize and align, giving phyllite its characteristic silky sheen and foliated texture. The high pressure and moderate heat conditions required for the formation of phyllite result in the development of fine-grained mica minerals such as muscovite or biotite within the rock.