ABSTRACT
Metamorphic rocks show variations in their mineralogical and microstructural features that are linked to variations in P–T conditions of metamorphism. At low P–T conditions, typical minerals are hydrous and generally of low density (e.g. Chl, Ms, Qtz and PI). With increasing P–T, less hydrous and anhydrous minerals become dominant (e.g. Stt, Grt, Ky, Pyx and Hbl). Similarly, with increasing P–T, grain size generally increases. There are a number of ways of monitoring these changes (i.e. classification) to record changing conditions.
