Cool fiber and cold silk are made by adding mica crystals and spinning during the spinning process What is mica? Mica belongs to aluminosilicate mineral, with continuous layered silica tetrahedron structure. The chemical formula is KAl2 [AlSi3O10] [OH] 2, in which SiO2 45.2%, Al2O3 38.5%, K2O 11.8%, H2O 4.5%. In addition, it contains a small amount of Na, Ca, Mg, Ti, Cr, Mn, Fe and F. As mica itself is a sheet structure, its thermal conductivity is better than that of PET and NYLON itself. The hydration effect formed by mica itself after delamination is easy to form a layer of hydration film. This double effect of "heat conduction+water absorption" is exactly the demand in summer, which is the reason why the yarn is cold.