Asarco is one of the world's leading producers of copper, with mines, smelters and refineries located throughout the United States. The company also purchases concentrates containing silver and gold from other mining companies. Concentrates bearing precious metals are processed at Asarco's copper smelters in Texas. The resultant sediments recovered from the smelters are used as feed for Asarco's precious metals refinery that has the capacity to produce more than 600,000 troy ounces of gold and over 60 million troy ounces of silver per year. Asarco manufactures two grades of bismuth oxide, including assay- and commercial-grade. The company s Globe Specialty Metals Plant, located in Denver, produces high-purity metals, and specialty compounds and alloys. Asarco is located in Tucson, Ariz.