U.S. Silica Holdings Inc., of Frederick, a producer of commercial silica used in the oil and gas industry, has been named No. 1 on Forbes’ 36th annual list of America’s Best Small Companies. Forbes ranked 100 companies with annual sales under $1 billion. The rankings are based on return on equity (28 percent for U.S. Silica), sales growth (22 percent) and earnings growth (60 percent) over the past year, as well as the past five years. Forbes also factors in stock performance versus each company’s peer group during the last 12 months.