Cata-, meso-, and epinorms are proposed for metamorphic rocks. The catanorm is essentially the CIPW norm calculated on the basis of molecular percentages and applied to high-grade metamorphic rocks.
The Rock Cycle is Earth's great recycling process where igneous, metamorphic, and sedimentary rocks can all be derived from and form one another. Analogous to recycling a Coke can, where an old can ...