The original rock has increased hardness due to dehydration, but the mineral composition is basically not recrystallized. It has a variable structure and a variable structure.
The appearance is dense and hidden crystals. The mineral particles are very fine and difficult to distinguish by the naked eye. There are often a small amount of sericite and other minerals on the board surface, which makes the board surface slightly shiny.
Slate can generally be named in detail according to different color impurities, such as black carbonaceous slate and gray-green calcareous slate. In the low-level thermal contact metamorphism, shallow metamorphic rocks with spot-like structures and plate-like structures can be formed, usually called "spotted rocks". Slate can be used as a building material and decoration material. In ancient times, it was often used as tiles in areas rich in slate.
