NERCO was an American mining company headquartered in Portland, Oregon, with interests in coal, natural gas, and oil. The company also had significant operations in gold and silver mining, and manufacture of gallium arsenide wafers. In 1993, NERCO was acquired for $470 million (and assumption of debt) by the Kennecott Corporation, a Utah-based subsidiary of the Rio Tinto Group. PacifiCorp owned 82% of NERCO stock at the time. Rio Tinto sold off NERCO's oil and gas operations later that year for $510 million.