They are formed by volcanic-caldera cycles that involve the creation of volcanic peaks from subsurface magma chambers and are distributed by segregating faults in basins and ranges.

The rugged and remote Sierita Mountains were mined for silver-lead deposits by Spanish explorers and missionaries for centuries, and were expanded to a wider extent in the mid-20th century with operations such as the Mission Mine Complex and the Twin Butte Open Pit Mine. copper has been mined in Geologically, the Sierita Mountains consist of an intrusive granite core surrounded by metamorphic rocks.

Sierritas is one of the few localities in Arizona to host aquamarine found in granite quartz veins. The mountains cover 60 square miles, 12 miles north-south and up to 6 miles wide. A gem variant of beryl, aquamarine, is documented from Palohis Verde and Belladonna claims. The whereabouts of these claims remains unknown as they have not been patented.

Other mines in and near the Sierita Mountains include the Copper Glance mine in the Twin Buttes Mining District, which had its own rail spur for ore transportation. He worked for copper from the late 1870s along with the Morgan Mine Senators.

Founded in 1903 and operated by Twin Buttes Mining & Smelting Co., the Senator Morgan mine was leased to Bush-Baxter from 1906 to 1913. Copper ore, together with silver, is worth over $2 million. Scheelite, an ore of tungsten (WO3), was later found in quartz deposits along with lime and silicified sandstone.

In 1942, Maurice d’Autremont and David Richards leased the land from Charles M. Taylor. Taylor discovered scheelite in quartz veins that had been disseminated the previous year using fluorescent lighting. For testing, he shipped over 100 tons of ore to Jacobs, his tungsten factory northwest of the intersection of Speedway and Silver Bell. A low grade value of 1.25% and poor geological conditions led to high mining costs and hampered ore production, and no further work was done after 1943.

The Silver Bell Mountains, west of Tucson, are home to the massive Silver Bell Open Pit Mine. The formation of Silver Bell’s copper deposit dates back 75 million years to him. They were created by intense volcanic activity, with thick layers of volcanic debris and magma chambers forming very deep beneath the surface. As the magma solidified, copper-rich fluids were released and carried to the surface along fault zones that spread along a network of fissures, forming the present-day copper mineral deposits.

Mining in the area was extensive, beginning in 1865 with the discovery of high-grade copper oxide ore at the Old Boot Mine. -Day Furnace built on site by Huachuca Mining and Smelting Company.

Ten years later, Silver Bell Mining Co. built a small Tucson smelter and refined ore for several years at the mine site.

By 1903, the Imperial Copper Co. was organized by the Development Co. of America or DCA, founded in 1901 by Eb Gage and WF Staunton. DCA was founded by magnate Frank M. Murphy to finance and oversee a network of mining and railroad operations in Arizona. .

The soon-established town of Silver Bell had a population of about 1,000. And by 1909, the Southern Arizona Smelter and Refinery (SASCO) had established smelters west of the company town of Sasco and Red Rock to process ore from the Silver Bell Mine. The town and smelter were cut short by the bankruptcy of his DCA, which included a mining operation at Tombstone, the Spanish flu pandemic, and falling copper prices.

Falling copper prices also forced ASARCO to suspend operations at the nearby Silverbell mine. This mine was developed by ASARCO in 1951 and included two of his ore bodies, El Tiro Pit and Oxide Pit, 2.5 miles apart. Copper production continues today.

The Helvetia Mining District, 30 miles southeast of Tucson at the northern end of the Santa Rita Mountains, contains more than 50 mines that may have operated sporadically since their discovery in the 1870s.

By 1899, the Helvetia mining camp was one of the largest mines in Pima County, employing over 300 miners as employees of the Helvetia Copper Company, with developments at Copper World, Exchange, Heavyweight, It took place at Isle Royale, Narragansett and Omega. mine.

Despite extensive development, including an 8,000-foot narrow-gauge railroad linking the mines in the Helvetia area to the 175-ton smelter, the mines themselves weren’t very profitable, but they were once in the South Pacific. Today the mine is of interest among mineral collectors for the specimens they produced.

The Flax Mine, located in the Harshaw Mining District four miles south of Patagonia, was a steady source of lead and zinc from 1884 to 1963. This mine was first discovered and owned in his 1850s and was selected for the highest production (over $3 million for the period). dollar) under ASARCO since 1940.

In 1919, a 6,200-foot-long aerial rope tramway connected the mine to a gravity flotation thickening mill with a daily capacity of 100 tons capable of processing lead carbonate. The operation was funded by the Flux Syndicate and lasted only a few years due to high operating costs. 4,000 tons of ore and tailings were milled, producing 14 of his truckloads of lead and silver concentrate worth $16,000 on the period market.

Geologically, the mine consists of rhyolite porphyry and associated volcanic deposits. The mine reached a level of 750 feet including over 6,000 feet of tunnels, shafts, drifts, crosscuts and stops before it became too low-grade to profit from the metals market. The lead concentrate was transported by rail to the El Paso smelter and the zinc concentrate he transported to the Amarillo smelter.