Common minerals are flaky mineral mica, granular minerals are mainly quartz, and feldspar content is less than 25%. It often contains characteristic metamorphic minerals such as andalusite, kyanite, garnet, cordierite, cross stone, epidote and blue amphibole.
The type of schist depends mainly on the type of original rock and is also closely related to the temperature and pressure conditions experienced. There are mainly mica schist, Calcium Silicate schist, green schist, magnesia schist, amphibole schist, blue flash schist.
Mica schist
Its original rocks are mainly argillaceous rocks and medium-acid volcanic rocks, calcareous sand shale and so on. The mineral composition is mainly mica, followed by quartz, plagioclase, garnet, kyanite, and cross stone. Mica schist is widely distributed and is often seen in areas where regional metamorphic rocks are distributed. The rock has a patchy crystal structure, and the plaque is a garnet. The matrix is ​​muscovite, biotite, quartz and a small amount of plagioclase. The variegated crystal sometimes has a wreck structure.
Green schist
The original rock is generally neutral to basic volcanic rocks, volcanic clastic rocks and calcareous dolomitic marl, etc., formed by metamorphism in low-level regions, and is a typical rock commonly found in the green schist facies. The mineral components are mainly chlorite, epidote, actinolite, albite, quartz, calcite, muscovite, and minerals such as magnetite, vermiculite and apatite.
Talc schist and serpentine schist
The ultrabasic rock and the iron-containing magnesium dolomitic marl are metamorphosed at a lower temperature. It is mainly composed of talc and serpentine, and also contains actinolite and chlorite.
Amphibole schist
The original rock composition is similar to that of green schist, which is formed by metamorphism of basic rocks and calcareous dolomitic marl at higher temperatures. The main mineral is ordinary hornblende, followed by quartz and plagioclase.
Blue amphibole schist
The blue amphibole schist is characterized by sodium-containing hornblende and sodium-containing pyroxene. Other common minerals include muscovite, chlorite, epidote, garnet, quartz, and albite. It is mainly composed of basic rocks and sandstones. The appearance of blue amphibole represents the metamorphic condition of high pressure, which is often distributed in the core of the orogenic belt. If accompanied by eclogite, it is related to the reentry of the lower crust rock after the subduction of the plate.
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