BISBEE, Ariz. (AP) -- Bisbee's underground mine tour may close.
According to city officials, safety concerns cited by Freeport-McMorRan include radon gas found in the mine.
The lease termination would take effect in 60 days, but Bisbee officials say they've referred the matter to the city attorney.
The tour is a popular tourist attraction.
The mine was closed as a working mine by Phelps Dodge Corp. in 1975.
Bisbee is about 3.5 hours southeast of Phoenix, near the Mexican border.