Hydromica is a group of minerals in the class of silicates . It differs from mica in a higher content of bound water, which is easily removed by heating, and in a lower content of cations forming bonds between the layers.
Hydromica is formed in the low-temperature stages of hydrothermal processes, during the weathering of igneous rocks and pegmatites from contained mica and feldspars . Some hydromica are formed by the absorption of complex potassium alumina gels and other alkaline elements from seawater. A necessary condition for the existence of hydromica is a water-rich environment.
Representatives of the group are illite , vermiculite , glauconite .
Widely used in industry and agriculture: in the production of porcelain stoneware ( illite ), heat and sound insulating materials and insulating materials for nuclear energy ( vermiculite ), as potash fertilizer ( glauconite ).