Composition and structure of slate

Shallow metamorphic rocks are formed by slight metamorphism of clayey, silty sedimentary rocks or intermediate-acid tuffaceous rocks and sedimentary tuffs. Black or gray-black. The lithology is dense and the plate cleavage is developed. There is often a small amount of sericite and other minerals on the plate surface, which makes the plate slightly show silk luster. There is no obvious recrystallization. Under the microscope, some mineral grains such as quartz, sericite and chlorite with uneven distribution can be seen, but most of them are aphanitic clay minerals and carbonaceous and iron powders. It is characterized by residual structure and spotted structure.
The original rocks with plate-like structure are mainly argillaceous rocks, argillaceous siltstones and intermediate-acid tuffs. Slate is a low-grade product of regional metamorphism, with low temperature and uniform pressure, and is mainly affected by stress. The metamorphic rock developed by plate cleavage mainly consisting of argillaceous and silty components, mainly consisting of argillaceous and silty components, mainly consisting of argillaceous and silty components. The slate with dense structure and developed foliation can be used as building stone, tablet, inkstone and other stones.