The precursor of one of these types of rocks is called the protolith, and slate is a type of it derived from shale.
The Barrovian sequence is used to classify types of this class of rocks by comparing them to index minerals. Andalusite and staurolite are common minerals found in them, an unusually dense type of which is found in subduction zones and called eclogite. Layering caused by shear on these rocks is known as foliation. Their "regional" form is formed by tectonic movement, while the "contact" type forms around magma intrusions. The precursor of one of these types of rocks is called the protolith, and slate is a type of it derived from shale. For 10 points, name this class of rocks formed after igneous or sedimentary rocks are exposed to extreme heat and pressure.
The Barrovian sequence is used to classify types of this class of rocks by comparing them to index minerals.
metamorphic rocks