Morenci Mine, Copper surface mine in Greenlee County, Arizona, US

Morenci Mine is an open-pit copper mine in Greenlee County, Arizona, just outside the company town of Morenci and the town of Clifton. Phelps Dodge began converting the former underground Longfellow Mine to open-pit working in 1937. Ore is hauled out on the Freeport-McMoRan Industrial Railroad, which interchanges with the Arizona Eastern Railway at Clifton.

The site began as an underground operation in 1871 and became an open-pit mine in 1937. This change allowed for large-scale industrial copper extraction in the region.

The mine's labor history is part of local identity: in 1903 mostly Mexican-descent workers struck for higher wages, and the 1983–1986 Arizona copper strike centered on Morenci, with strikers blocking the entrance after Phelps Dodge hired strikebreakers.

The mine lies just outside the company town of Morenci and the town of Clifton in Greenlee County. It is an active industrial site served by the Freeport-McMoRan Industrial Railroad, which interchanges with the Arizona Eastern Railway at Clifton; the line carries sulfuric acid in and copper concentrate out. There is no public visitor access to the pit.

The mine's ore carts were hauled by mules when the Longfellow Mining Company opened the underground workings in 1871. A Freeport-McMoRan Industrial Railroad links the site to the Arizona Eastern Railway at Clifton, carrying sulfuric acid in and copper concentrate out.