MINERALS

The principal use of ground mica is in gypsum wallboard joint compound, where it acts as a filler and extender, provides a smoother consistency, improves workability, and prevents cracking. In the paint industry, ground mica is used as a pigment extender that also facilitates suspension due to its light weight and platy morphology. The ground mica also reduces checking and chalking, prevents shrinkage and shearing of the paint film, provides increased resistance to water penetration and weathering, and brightens the tone of colored pigments. Ground mica also is used in the well-drilling industry as an additive to drilling “muds.”