U.S. Silica Mauricetown Plant conducted the STAY OUT STAY ALIVE program, June 6-8, 2011

U.S. Silica Holdings, Inc. is a performance materials company and is a member of the Russell 2000 Index. The Company is a leading producer of commercial silica used in a wide range of industrial applications and in the oil and gas industry. Over its 119-year history, U.S. Silica has developed core competencies in mining, processing, logistics and materials science that enable it to produce and cost-effectively deliver over 1,500 diversified products to customers across our end markets. U.S. Silica's wholly-owned subsidiaries include EP Minerals and SandBox Logistics™. EP Minerals is an industry leader in the production of products derived from diatomaceous earth, perlite, engineered clays, and non-activated clays. SandBox Logistics™ is a state-of-the-art leader in proppant storage, handling and well-site delivery, dedicated to making proppant logistics cleaner, safer and more efficient. The Company currently operates 27 mines and production facilities. The Company is headquartered in Katy, Texas and has offices in Frederick, Maryland, Reno, Nevada and Chicago, Illinois.