The dictionary defines mica as "A class of silicates having a prismatic angle 120 degree, eminently perfect basal cleavage, affording thin tough laminae or scales, colorless to jet black, transparent to translucent, of widely varying chemical composition, and crystallising in the monoclinic system".
          In brief, mica is a generic term applied to a group of a complex aluminosilicate minerals having a sheet or plate like structure with different chemcial compositions and physical properties. All micas from from flat six-sided monoclinical crystals with a remarkable cleavage in the direction of the large surfaces,which permits them to split easily into optically flat films, as thin as one micron in thickness. When split into thin films, they remain tough and elastic even at high temperature.