Rio Tinto will continue to work on building support for it Resolution copper project in Arizona from the San Carlos Apache tribe that has opposed the project.

The Resolution copper project is key to Rio Tinto’s future. It could supply as much as a quarter of the United States’ copper needs and produce more than 40 billion pounds of copper.

The project has faced opposition for years because it lies below the federally owned Oak Flat Campground, a place some Apache consider home to deities.

The mine would create a crater 3 km (2 miles) wide and 304 m (1,000 ft) deep that would destroy that worship site, which the San Carlos Apache tribe strongly opposes.

Reuters reported that the tribe has refused to meet with Rio Tinto, saying it prefers to negotiate directly with the U.S. government, which in 2014 approved a complex process to give Rio Tinto the land containing the copper in exchange for acreage that Rio Tinto owns nearby. President Joe Biden put that land swap on hold in 2021.

Some other Apache tribes in the area support Rio’s project, but the San Carlos Apache have vowed to block it. Rio said it will continue to try to win the San Carlos Apache’s approval.

“We have to have broad-based support, for sure,” Bold Baatar, Rio’s chief executive of copper, told Reuters on the sidelines of the CERAWeek energy conference in Houston, TX. “If there are going to be opposing voices, we’re going to continue trying to engage.”

Several courts have ruled against the San Carlos Apache and their allies, which have appealed to the full 9th US Circuit Court of Appeals. That court plans to hold a hearing to consider the case on March 21.

The company said it may be able to prevent the large crater, but will not know if that is possible until it controls the land. “When you get through mine planning and start touching rock, we will looking for areas of improvement to try to mitigate the impact as much as possible,” Baatar said.

U.S. Representative Raul Grijalva, an Arizona Democrat, introduced legislation to reverse the 2014 legislation approving the land swap.

The project would involve digging into a new rock deposit using a mine shaft that closed in the 1990s and related electrical infrastructure. Rio has begun positioning the project as the expansion of an old mine, which tend to be more palatable for regulators and local communities.

“Resolution is not a greenfield mine,” said Baatar. “It’s a revival of old, proud U.S. copper history and an old mine that was there. It’s just deeper.”