The Mule Mountains are a north/south running mountain range located in the south-central area of Cochise County, Arizona. The highest peak, Mount Ballard, rises to 7,500 ft (2,300 m). Prior to mining operations commencing there, the mountains were heavily forested with large Rocky Mountain Douglas-fir (Pseudotsuga menziesii glauca) and other conifers, but these were all cut down for housing needs and to feed the ore smelting furnaces in Douglas, Arizona, approximately 20 miles due east. Now, the primary vegetation of the Mules consists of manzanita (Arctostaphylos spp.) brush, juniper, lowland oaks and pines, and various grasses. To the east of the mountain range lies Sulphur Springs Valley, and the San Pedro River and Valley to the west.
The terrain is very rough, with very steep slopes descending into deep canyons. Common wildlife species include Mule deer (Odocoileus hemionus), White-tailed deer (O. virginianus), Collared Peccary (Pecari tajacu), various types of rodents, lizards and a wide variety of birds. The upper ridges of the mountains consist primarily of a very hard brecciate limestone, and it is very common to find fossils of clams and snails imbedded in them.