Mica is a mineral that is commonly used in the electrical industry, to produce shingles and other building materials, and to prepare samples for microscopy. It has also been used to create window-like panes on stoves and lanterns, and to facilitate pigment suspension in paints and dyes. Its sheet-like cleavage structure and high heat resistance make it an ideal substance for these purposes.
According to the Minerals Education Coalition, mica is a key component in wallboard joint compound because it gives a smooth consistency and prevents the dried substance from cracking. It is also added to paint because it keeps the pigments from separating from the paint base, promoting a more even color. Mica also makes paint more water-resistant. It is added to plastics for the same reasons -- it provides reinforcement and helps molded products achieve their shapes without cracking.
Mica is commonly used in the electrical industry because of its ability to withstand heat, conduct electricity and withstand high voltage. High-quality muscovite mica is commonly used as a dielectric substance in capacitors, and large sheets of mica are used as backing for heating wires because of their high heat tolerance. In microscopy laboratories, much smaller sheets of mica are used to mount tiny samples allowing for visualization of plasma membranes and even DNA molecules.