Greenschist

Classification：Metamorphic Rock

The regional metamorphic rocks in the sheet structure are green minerals, such as epidote, chlorite, and Yang Qi, and the green schist is usually metamorphic magnesia igneous rocks. If green minerals are chlorite, they are chlorite schist.

Greenschist is a general description of the metamorphic rocks from greenish to dark green with fine-grained and flaky texture.

Mineral composition:
Greenschist is mainly composed of chlorite, epidote, heathenite, Actinolite and other green minerals and albite, quartz, sericite, Xie Changshi, black mica, and sometimes contain a small amount of calcite, and the accessory minerals include magnetite, spite, apatite and so on. The columnar minerals are aligned, forming fibrous and flaky crystalline structures, flaky to thousands of grains. According to the main dark minerals, they can be divided into green mud schist, Yang rise stone rock and so on. According to the mineral assemblage, they can be divided into green curtain sodium chlorite schist, green curtain chlorite schist, green curtain sodium Changyang schist and green mud sodium Changyang schist and so on. When did not develop, called greenstone schistosity.

Distribution:
Greenschist, one of the regional metamorphic rocks, is mainly developed in the orogenic belt, and is often an important part of the Archean greenstone belt. Greenstone is widely distributed in China, such as Qilian Mountains, Qinling Mountains, Sichuan and Longmen mountains.

Research significance:
Greenschist is a low-grade metamorphic temperature and pressure conditions of metamorphism is relatively high with the formation of the facies significance. The protolith is intermediate, basic volcanic rocks, tuff and argillaceous sedimentary rocks rich in Fe, Mg and ca. It is a product from basic to low grade metamorphism.

Characteristics of the original rock:
The original rocks of Greenschist are usually neutral to basic volcanic rocks, pyroclastic rocks and calcareous dolomite marlite, which are formed by low-grade to intermediate zone metamorphism, and are typical typical rocks in the Greenschist phase. Most of them are formed by shallow metamorphism of basic and ultrabasic igneous rocks. Sometimes they can also be metamorphosed by sedimentary rocks rich in Fe and Mg.

Identify：
Generally, Greenschist is light yellow green, medium fine grain and massive structure. Its main minerals are diopside, epidote, garnet, Yang Qishi, chlorite, a small amount of quartz and calcite. Moreover, Greenschist is mostly filled with quartz veins and locally silicified, and Greenschist contains disseminated lead-zinc mineralization.