The terrain is very rough, with very steep slopes descending into deep canyons. Common wildlife species include mule and whitetail deer, javelina, 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.
Immediately to the east central area of the Mules lies the Lavender Pit, a large and very deep open pit copper mine dug and mined by the Phelps Dodge Corporation between 1951 through 1974. Over a billion tons of copper were extracted from the mine, along with significant quantities gold, silver and lead. Also, as a by-product of the mining operations, high quality turquoise (locally known as Bisbee Blue) was also discovered.
On the east central slope of the Mule Mountains can be found the Copper Queen Mine. In its days of production, (late 1800s – early 1900s) it was the richest copper deposit ever discovered, causing the accompanying town of Bisbee, Arizona to highly prosper, becoming the largest city between Saint Louis in the east, and San Francisco in the west for a short while. Much of the Mule Mountains are laced with mining tunnels dug in pursuit of the rich copper ore. Today, Bisbee (also known as the "mile-high city," at elevation 5,300 feet) is largely a tourist town and retirement community along the slopes of Tombstone Canyon in the heart of the Mules. There are currently no organized mining operations in effect in the Mule Mountains. Much of the east/southeastern area of the range is considered private property, owned by Phelps Dodge Corporation.