The United States has no reserves of sheet mica. India is by far the largest producer and provides most of the U.S. and world supply. Scrap and flake mica is mica that is unsuitable for use as sheet mica. It is ground to various sizes and used as a filler and/or extender in wallboard joint compounds, paints, and plastics; as an ingredient in well-drilling muds; as a lubricant; and for various other uses. In 1991, estimated 94,000 metric tons of scrap and flake mica valued at about $5.1 million was produced in the United States. The mica was processed to produce an estimated 84,000 metric tons of ground mica valued at $19 million.