acres of what is now the Tonto National Forest off limits to visitors.

Under the forest, in a process called "block cave mining," Rio Tinto will excavate material from underground, making the material above sink and creating the expected one-and-a-half-mile-wide crater.

That area will include a site considered sacred to the San Carlos Apache Tribe, which has been holding annual protests against the project.

Years of scrutiny

If Resolution's copper deposit had been discovered under private land - and not a national forest - Rio Tinto might have been spared the federal review and faced only state regulators. Instead, the U.S. Forest Service is leading the study, which will consider jobs, recreation, public health and wildlife.

Despite its substantial economic benefits to the nearby town of Superior, where many homes and businesses areto approve or reject mining projects.

Mining companies in Canada and Australia applaud similar time limits in those countries, but a May 2016 report by a government watchdog in the Canadian province of British Columbia found Canada's mine regulation had "major gaps in resources, planning and tools" that led to "inadequate" inspections and "increasing environmental risks."

Commerce Secretary Ross told Reuters in a June 23 phone message he believed the Forest Service was doing "a good job in terms of Rio Tinto." But he added, "The rest of the process has been so abysmal that Rio Tinto actually testified before the U.S. Congress (about) how bad the process was."

Ross and his spokesman did not respond to additional questions seeking examples of problems that occurred between Resolution and permit-issuing agencies.

But his