The Bronco Canyon watershed is located almost at the exact geographical center of the state of Arizona. This extremely rugged area lies between the Aqua Fria River to the west and the Verde River to the east. Both rivers flow southward, the Aqua Fria on its way to the Gila and the Verde River heading to its junction with the Salt River. Bronco Canyon is located about 50 miles north of Phoenix and about 25 miles northwest of old Fort McDowell. The famous Bradshaw Mountains loom to the west less than 20 miles away. This southern portion of the Bradshaws is home to a number of rich mining operations including the Crown King, Tiger, and Howard mines.
The 1870's were the glory years of the southern Bradshaws. The area was alive with excitement as prospectors scrambled through the mountains in search of gold. In 1870, the fabulous Tiger lode was discovered near the southern crest of the range. Five years later, a school teacher stumbled on a massive gold deposit less than three miles north of the Tiger Mine. Initially dubbed the Red Rock Mine, the famous deposit eventually came to be known as the Crown King Mine.
The fabulous strikes in the southern Bradshaws galvanized the area. It seemed like every man in central Arizona was on the lookout for gold. During those early years of the 1870's, any prospector riding into Phoenix with gold ore in his packs was likely to attract attention. If that man was an Indian then it was a sure thing that all eyes would be on him. Such a thing occurred at this time in Phoenix.
The Apache Indian had been showing up in Phoenix to trade for food and supplies for many months. He never made trouble and he always paid for his supplies with gold nuggets! Phoenix was filled with prospectors going to and from the mines. Some of those prospectors had heard of the Apache Indian who never seemed to lack for gold. Two of them in particular decided to follow the Apache back to his gold mine. One day they managed to track him north out of Phoenix. Eventually, they reached the rugged Bronco Canyon area where, on the west side of the canyon, they found a massive quartz vein laced with free gold. Unfortunately, the Apaches attacked the prospectors, killing one. The other slipped away and escaped. Years later, before he could return to the mine, the old prospector passed away. The Apache's gold mine remains hidden to this day.
Many of the creeks, canyons, and arroyos of the southern Bradshaws contain placer gold deposits. Turkey Creek, which drains the east flank of the southern Bradshaws north of Cleator, has been a minor but steady producer. The Black Canyon drainage area has also yielded placer gold, especially between Arrastre Creek and Poland Creek. The gravels below the Howard mines were locally quite rich.
The nearest zone of mineralization lies in the southeastern part of the area of interest. Several mines and prospect pits lie about 9 miles east of Black Mesa. These include the Brooklyn, Rosalie, and Copper Queen Mines. These deposits are hosted in Precambrian basement rock, like those in the Bradshaw Mountains.