Schist is classified as a foliated metamorphic rock. This means it has a pronounced layering or banding due to the parallel alignment of platy minerals such as mica, which gives it a distinctive sheen and texture. The foliation in schist is often the result of high-grade metamorphism, where intense heat and pressure have caused the minerals to realign and form visible layers.
The alignment of the minerals not only gives schist its schistosity (the property of being schistose) but also makes it quite different from nonfoliated rocks, like marble or quartzite, which do not exhibit such layering. Overall, schist is a prime example of foliated metamorphic rock and showcases the effects of metamorphism on parent rocks.