Slate is a type of shallow metamorphic rock. Formed by slight metamorphism of clayey, silty sedimentary rocks or intermediate acidic tuffaceous rocks and sedimentary tuffaceous rocks; Black or grayish black, with dense lithology and well-developed plate-like cleavage. There are often a small amount of minerals such as sericite on the surface of the board, which gives the board a slight silk luster. There is 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 cryptocrystalline clay minerals and carbonaceous and iron powders. It has a variable residual structure and a spotted structure. Common types include carbonaceous slate, calcareous slate, black slate, etc; According to other characteristics of rocks, such as mineral composition, structural structure, etc., they can also be divided into calcite slate, speckled slate, silty slate, silicate slate, etc. Shale is widely distributed in rock series subjected to low-temperature dynamic metamorphism in the region, such as the Doucun shale of the early Proterozoic Hutuo Group in northern China, and the Banxi Group and Kunyang Group of the mid late Proterozoic in southern China. Can be used as building stone.
From a geological perspective, "slate" is a type of metamorphic rock. According to the structural classification of metamorphic rocks, there are phyllite, shale, gneiss, slate, etc. Rocks with plate-like structures are called slate. This indicates a concept that "slate" is a metamorphic rock with lithological features of plate-like structures. In real life, the connotation of "slate" that people are familiar with is very broad. More often than not, it is called "slate" or "stone slab", which is the name of a commodity. Any stone with natural features that can be processed into sheets or thin plates is called "slate". Most slate has strong durability and is resistant to acid and alkali.
