ABSTRACT
Metamorphic rocks display a wide range of chemical compositions and mineral assemblages, reflecting the variety of original rock types that become metamorphosed. Metasedimentary rocks can broadly be subdivided into three main categories; namely, metapelites, metacarbonates/calc-silicates and quartzofelds-pathic metasediments. There is of course a complete spectrum of rocks between these end-members (Fig. 3.1). In addition to metasedimentary rocks, there are three main compositional groups of meta-igneous rocks; namely, metabasites, metagranitoids and metaultrabasics. The mineralogical and chemical characteristics of these various metamorphic rocks are now discussed, with emphasis on key minerals and assemblages. The mineral abbreviations used throughout this book are those suggested by Kretz (1983), and extended by Bucher & Frey (1994). For quick reference, they are tabulated in Appendix I. A ternary diagram illustrating the nomenclature in common use for metasedimentary rocks based on the relative proportions of quartz, micas and carbonate minerals. https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315831626/67ff2ae0-2ee0-4d05-9e97-aa4df451c794/content/fig3_1_B.tif" xmlns:xlink="https://www.w3.org/1999/xlink"/>
