Mining company Unimin specializes in industrial minerals. The company's products include ball clay, barium sulfate, bentonite clay, calcium carbonate, dolomite, feldspar, high-purity quartz, kaolin, microcrystalline silica, olivine, and talc. Unimin sells its products to customers in a broad range of industries, including producers of industrial ceramics, fiberglass, fiber-optics, glass, oil and gas, paint and coatings, quartz lighting, and semiconductors. It makes quartz proppants and resin-coated proppants used by oil and gas producers in hydraulic fracturing (fracking). The company is a member of Belgium-based Sibelco Group, which operates more than 250 mines and plants in 41 countries on five continents.