Slate composition structure and structure

The shallow metamorphic rocks are formed by slight metamorphism of clayey and silty sedimentary rocks or intermediate-acid tuff rocks and sedimentary tuff rocks. Black or grayish black. The lithology is tight, with well-developed plate-like cleavages. There are often a small amount of sericite and other minerals on the surface of the board, which makes the surface of the board slightly silky. There was no obvious recrystallization phenomenon. Under the microscope, some unevenly distributed mineral grains such as quartz, sericite, and chlorite can be seen, but most of them are aphaphatic clay minerals and carbonaceous and iron powders. With variable structure and spot-like structure.

The rock protoliths with plate structure are mainly argillaceous rock, argillaceous siltstone and intermediate-acid tuff. Slate is a low-grade product of regional metamorphism, its temperature and isotropic pressure are not high, and it is mainly affected by stress. Metamorphic rocks mainly composed of argillaceous and silty components, with plate-like cleavage development, and slate with dense structure and well-developed slabs It can be used as building stone, stele, inkstone and other stone materials.