U.S. Silica Holdings, Inc. makes & markets commercial silica, to a variety of end markets in the U.S. To serve a wide gamut of end markets, U.S. Silica makes and distributes a range of commercial silica products including whole grain and ground products as well as other industrial mineral products that complement its commercial silica products. Oil & gas proppants is its biggest end market. The company's frac sand is used to stimulate and retain the flow of hydrocarbons in oil and natural gas wells. Its silica is also used as a raw material in industrial applications including glass, building products, foundry products & chemicals. The company distributes its commercial silica products direct to its customers. It has 2 segments: Oil & Gas Proppants and Industrial & Specialty Products. Its customers in the oil & gas proppants market include major oilfield services companies engaged in hydraulic fracturing. It acquired EP Minerals, a global producer of engineered materials derived from industrial minerals.