SUPERIOR, Ariz. (AP) â¿¿ An Arizona mining company says it will suspend shaft and drilling work at its Superior operation and eliminate approximately 400 jobs as a result of continued uncertainty regarding a proposed land exchange. Resolution Copper Mining says it'll try to place affected workers within other operations of Resolution or its parent company, Australia-based BHP Hilton. The job reductions amount to about 75 percent of Resolution's workforce. The reductions are to start by the end of December and concluded by the end of March. Resolution would swap 5,300 acres of land for conservation purposes for 2,400 acres of national forest land that company calls critical for its expansion plans. The exchange has been stalled in Congress for years, opposed by some conservationists and American Indians.