History of the Ajo Mining District, Pima County, Arizona D.F. Briggs | Geologist Aerial photograph of Ajo mining complex, 1956; courtesy of Freeport-McMoRan Inc. CONTRIBUTED REPORT CR-17-A March 2016 Arizona Geological Survey www.azgs.az.gov | repository.azgs.az.gov Arizona Geological Survey Phil A. Pearthree, State Geologist and Director Manuscript approved for publication in March 2017 Printed by the Arizona Geological Survey All rights reserved For an electronic copy of this publication: www.repository.azgs.az.gov For information on the mission, objectives or geologic products of the Arizona Geological Survey visit www.azgs.az.gov. This publication was prepared by a department at the University of Arizona. 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Moreover, the Arizona Geological Survey shall not be liable under any circumstances for any direct, indirect, special, incidental, or consequential damages with respect to claims by users of this product. The author(s) is solely responsible for the data and ideas expressed herein. Recommended Citation: Briggs, D.F., 2017, History of the Ajo Mining District, Pima County, Arizona. Arizona Geological Survey Contributed Report, CR-17-A, 16 p. History of the Ajo Mining District, Pima County, Arizona David F. Briggs, Geologist The hostile environment of southwestern Arizona’s missions and mines vulnerable to Indian raids and low desert presented many challenges to those who outlaw depredations. Although protection was sought to discover and exploit the mineral wealth gradually reestablished following the revolution, of the region. Ajo’s remote location combined with significant mineral exploration and development did hot summer days and scarce water created a number not resume until the mid-1850’s (Greeley, 1987). of obstacles that needed to be overcome. Despite these impediments, the district’s wealth was mined In 1847, Tom Childs, a member of a group of 19 by Native Americans long before the arrival of first prospectors exploring the Cubabi Mountains southeast Spanish explorers, who recognized its potential soon of Sonoyta, Sonora, heard rumors of a copper prospect after establishing outposts in this region. at three little peaks north of the town of Sonoyta at a site named Ajo. On their return to Tucson, the Many years passed before mining professionals with prospecting party found evidence of this early mining the knowledge, skills and financial backing achieved activity in the area that would become the Ajo mining commercially viable copper operations at Ajo. district, including shallow open cuts in the hillside and Application of new technologies and mining practices a 60-foot inclined shaft that was accessed by ladders enabled them to develop Arizona’s first large copper made from notched mesquite logs. They also found operation to successfully employ open pit methods. buckets fashioned from rawhide that were used to extract the mined material by hand (Greeley, 1987). Early History (Prior to 1899) With the signing of the Treaty of Guadalupe Hidalgo at Tohono O’odham Indians and their ancestors mined the end of the Mexican American War on February 2, hematite from the hills around present day Ajo for 1848, the United States acquired California, Nevada, many centuries prior to the arrival of the first Spanish Utah and portions of Colorado, Wyoming, New Mexico explorers during the 1530s. Used as body paint, and Arizona. Unknown to both governments, gold hematite was dug from shallow pits at a site known had been discovered by James W. Marshall at Sutter’s to the Indians as “au àuho,” which means paint. Later sawmill in Coloma, California on January 24, 1848, explorers used a similar sounding Spanish word, “Ajo”, nine days prior to the signing of this treaty. As news meaning garlic, as the name of this site (Greeley, of this discovery became known, prospectors from 1987). northern Sonora used El Camino del Diablo (aka the Devils Highway) to reach the California goldfields. During the late 1600s, Jesuit missionaries established Connecting Altar, Sonora and Yuma, Arizona, this trail numerous missions in northern Sonora and passes very close to Ajo (Greeley, 1987). southern Arizona, including a mission at Sonoyta in 1693. These early settlements served as bases A portion of southwestern New Mexico and Arizona for early prospectors, who intermittently explored south of the Gila River was purchased from Mexico and developed primitive mining operations in the for $10 million through the successful completion of surrounding mountains. As more settlers arrived, the Gadsden Purchase in June 1854. This acquisition there were episodic conflicts with the Indians, resolved outstanding border issues with Mexico including the Pima Revolt of 1751. These uprisings following the end of the Mexican American War disrupted mining activities at the remote sites. This and provided a favorable terrain to construct a unrest led to the establishment of a number of transcontinental railroad along a southern route. presidios - fortified bases - including Santa Gertrudis de Altar (1755) in northern Sonora and San Ignacio Returning to Texas from the California goldfields de Tubac (1752) and San Augustin de Tucson (1775) in 1850, Peter Rainsford Brady met Tom Childs in in southern Arizona. At the outset of the Mexican Tucson, who told him about his prospecting trip to Revolution (1810-1821), the withdrawal of Spanish Ajo several years earlier. In 1853, Peter Brady joined troops from the region left many of the settlements, the survey party led by Colonel Andrew B. Gray, who 1 History of the Ajo Mining District, Pima County, Arizona had been assigned the task of finding a suitable route Little further activity occurred at Ajo until 1884, when for the southern transcontinental railroad, connecting Tom Childs formed a partnership with Washington Indianola, Texas with San Diego, California. While M. Jacobs, who established an assay office in on this expedition, the survey party passed through Tucson, Arizona in March 1880 and had previously the town of Sonoyta, Sonora. With the help of a worked for the Arizona Mining and Trading Company Seri Indian guide, Brady visited the Ajo site, where (Anonymous, 2016a). Jacobs established a permanent he gathered a number of rich ore samples. After camp at Ajo and over the next 14 years intermittently completing this survey project, Peter Brady went transported high-grade ore via wagon to a Southern to San Francisco, where he established the Arizona Pacific rail siding at Gila Bend from which it was Mining and Trading Company in August 1854. Other shipped to the Selby Smelting Company in San notable shareholders of this business venture included Francisco (Greeley, 1987). They also erected a small Robert Allen, Tom Childs, Colonel Andrew Gray, mill at the site in 1897 (Anonymous, 2016a). Granville Oury and Frederick Ronstadt (Greeley, 1987). As an important side note, Washington Jacobs’ Shortly after the Arizona Mining and Trading Company descendants remained in the assaying business, began prospecting the area in October 1854, several running the family assay office in Tucson until July wealthy citizens of Sonora claimed Ajo was located 2011, when his great grandson Michael Jacobs retired. in Mexico. In March 1855, a company of Mexican At the time of its closure, the 131-year old Jacobs cavalry was sent to Ajo to arrest Americans working at family business was the oldest assay office in the the site. This confrontation produced a skirmish that United States (Anonymous, 2016a). resulted in the Mexican cavalry returning to Sonora empty handed. By September 1855, an official survey Promoters and Fraudulent Mining of the United States-Mexico boundary had been Schemes (1898-1908) completed, with Ajo being located approximately 40 miles north of the border (Gilluly, 1946). With the sale of Childs’ and Jacobs’ holdings to a mining promoter named A. J. Shotwell during the fall By the end of 1855, 17 mining claims had been of 1898 for $200,000, the history of the Ajo mining located near Ajo, a wagon road constructed to district took a decidedly negative turn. Shotwell, with Petato (now known as Gila Bend) and local Tohono the financial assistance of John Boddie, a successful O’odham Indians were hired to help mine the ore. dry goods salesman from St. Louis, Missouri, Approximately 10 tons of hand-sorted, high-grade ore, organized the St. Louis Copper Company to finance consisting mostly of cuprite and native copper was the construction of a 10-stamp mill. Producing only transported 300 miles by ox-drawn wagons through $36,000 of concentrates at a cost of $45,000, this Fort Yuma to the port of San Diego and shipped business venture ended in bankruptcy. Undaunted by boat around Cape Horn to Swansea, Wales for by the previous failure, Shotwell formed the Rescue smelting. Later ore shipments were transferred to Copper Company as a way to salvage its predecessor’s barges at Fort Yuma and floated down the Colorado assets. This company subsequently sold a portion River to the port of Guaymas, Sonora on the Gulf of its holdings to the Cornelia Copper Company, of California for trans-shipment to Swansea, Wales.