Mica/ˈmaɪkə/ Definition 1 of 1Pro Tip 1/3Industrial Use Mica is mainly used in electronic and electrical devices due to its insulating properties. The mica in your hair dryer prevents electrical shocks. Pro Tip 2/3Sheet Appearance Mica appears as translucent, layered sheets that can be peeled apart. She peeled off a sheet of mica from the rock, marveling at its transparency. Pro Tip 3/3Cosmetic Use Mica powder is often used in makeup for its shiny, glittery effect on the skin. The eyeshadow's shimmer comes from finely ground mica.