The reserves are part of the St. Peter Sandstone Formation that stretches north-south from Minnesota to Missouri and east-west from Illinois to Nebraska and South Dakota.

The deposit has a minimum silica (SiO2) content of 99%. The controlling attributes are grain crush strength, iron (Fe2O3) content and grain size distribution. Iron is concentrated near the surface, where orange iron staining is evident and also increases where the bottom contact becomes concentrated in iron pyrite. Maximum average full-face iron content is 0.045%. The deposit tends to exhibit a coarser grain size distribution in the top half of deposit

Company surface mines in Ottawa use natural gas and electricity to produce whole grain and ground silica through a variety of mining methods, including hard rock mining, mechanical mining and hydraulic mining.

Company acquired the Ottawa facility in 1987 by merger with the Ottawa Silica Company, which historically used the property to produce whole grain and ground silica for customers in industrial and specialty products end markets. Since acquiring the facility, the Company renovated and upgraded its production capabilities to enable it to produce multiple products through various processing methods, including washing, hydraulic sizing, grinding, screening and blending. These production techniques allow the Ottawa facility to meet a wide variety of focused specifications on product composition from customers. As such, the Ottawa facility services multiple end markets, such as glass, building products, foundry, fillers and extenders, chemicals and oil and gas proppants. In November 2009, we expanded the frac sand capacity by 500,000 tons. During the fourth quarter of 2011, we completed a follow-on expansion project that added an additional 900,000 tons of frac sand capacity.

The ........