The United States Court of Appeals for the Ninth Circuit upheld a lower court ruling rejecting requests to block the transfer of more environmentally sensitive land to the USFS. Rio Tinto, the project's majority owner, holds a 55% stake in the underground mine, while BHP holds a 45% interest. The exchange allows Rio to transfer more than 5,400 acres of environmentally and culturally sensitive land in Arizona for inclusion in national forests and conservation areas. In return, BHP received approximately 2,400 acreage adjacent to the historic Magma copper mine. The project, which could become the largest copper mine in North America, has an estimated resource of over 40 billion pounds of copper with a 1.5% grade, could supply up to 25% of America's copper demand over a potential 40-year mine life.