Rio Tinto last week announced that they found an additional 628 million tons of copper ore (at 0.48% copper) below the current Bingham Canyon mine [right: copyright Michael Collier] outside Salt Lake City, Utah. According to Forbes.com, that brought the new total to 637 million tons, meaning the mine previously had only 8 million tons left.
Rio Tinto is the operator of the proposed Resolution copper mine in Superior, AZ, in partnership with BHP Billiton.
This discovery begs the question, do Arizona copper mines have similar potential resources under their current known resources?