Above is an example of quartz on schist.
Color: Silvery to gray (muscovitic types)and brown to black (biotitic types). Varies by the amount and type of mica.
Grain Size: Varies from very fine to somewhat coarse. Always evident is the flat to slightly wavy pattern known as "schistosity". Generally considered a fine-banded rock whereas gneiss is considered a coarse-banded rock.
Environment: Often associated with gneisses and are found throughout the world wherever metamorphic rocks are found. Schists are known to contain various gem minerals including garnets and beryl.
Schist falls in broad categories of both metamorphosed igneous rocks and metamorphosed sedimentary rocks. In igneous rocks which are foliated after solidification hornblende schist is an example. In sedimentary rocks that are foliated, mica schist is found along with hornblende schist and gneiss.
References: Introduction to Physical Geology by W. J. Millet, Rocks and Minerals by Simon and Schuster and A guide to Field Indentification of Rocks and Minerals by Sorrell and Sandstrom.
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