Schist

Classification：Metamorphic Rock

It is composed of flaky, columnar and granular minerals. In the process of regional metamorphism, mineral composition is rather complicated.

Schist is a metamorphic rock with typical flaky structure, and it is a product of regional metamorphism. It is characterized by the tectonic foliation, sheet, plate, mineral fibers are parallel, coarse grain size, discernible. The main minerals are mica, quartz, hornblende, chlorite and so on. Low strength, easy weathering and poor frost resistance.

Components:
The common minerals are flaky mineral mica and quartz minerals, mainly quartz and feldspar. Often contain andalusite, kyanite, cordierite, garnet, staurolite, epidote and glaucophane characteristics of metamorphic minerals.
The type of Schist mainly depends on the original rock type, 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 and so on. [2]

Features：
There is a characteristic of schistosity structure, regional metamorphic rock is common. The protolith has been recrystallized, consisting of flaky, columnar and granular minerals. General lepidoblastic texture, fibrous crystal structure change and metacrystal structure. [2]

[type]:

Mica Schist:
They are mainly argillaceous and intermediate acid volcanic rocks, calcareous sand shale and so on. The main mineral composition of mica, quartz, followed by Xie Changshi, garnet, kyanite and staurolite. Mica Schist is widely distributed, and is often seen in the distribution area of regional metamorphic rocks. Rock porphyritic crystal structure change, as porphyroblastic almandine. The matrix is Muscovite, biotite, quartz and a small amount of plagioclase. The variegated crystals sometimes have a stump structure.

Green Schist:
The original rocks are generally neutral to basic volcanic rocks, pyroclastic rocks and calcareous dolomitic marl, which are formed by low-grade metamorphism and are typical typical rocks in the green Schist phase. Mineral composition is mainly composed of chlorite, epidote, Yang Qishi, albite, quartz, calcite and muscovite. The accessory minerals include magnetite, sphagite and apatite.

Talcum snake Schist:
It is metamorphosed from ultrabasic rocks and dolomitic marl containing iron and magnesium at low temperature. Is mainly composed of talc and serpentine, also contain actinolite, chlorite.

Hornblende Schist:
The composition of protolith is similar to that of green Schist, which is metamorphosed from basic rock and calcareous dolomitic marl at high temperature. The main minerals are ordinary hornblende, followed by quartz and plagioclase.

Blue amphibole Schist:
The characteristics of the blue amphibole Schist are sodium amphibole and sodium containing pyroxene. Other common minerals are muscovite, chlorite, epidote, garnet, quartz and albite. It is mainly metamorphosed from basic rock and sandstone. The appearance of blue amphibole, which represents the metamorphic condition of high pressure, is often distributed in the nuclear part of the orogenic belt, which is associated with the eclogite, which is related to the reentry of the lower crust after subduction of the plate.