United States Antimony Corporation (USAC) is a natural resource company. It is a fully integrated mining, transportation, milling, and smelting operation that supplies three major products: antimony, precious metals, and zeolite. The company specializes in underground and open-pit mining, flotation and gravimetric milling, crushing and screening, dry grinding, cyanide leaching, precious metal refining, pyro-metallurgy, and marketing.