Some Arizona mines and their valuable minerals

William P. Blake, director of the School of Mines at the University of Arizona and territorial geologist, published the first list of minerals found in Arizona in 1866 and a more comprehensive list of 102 species in 1909.

Arizona is currently known to host 992 valid mineral species, and no doubt more will be discovered in the future. There are currently around 6,000 types of minerals based on crystal structure and chemical composition recognized by the International Mineralogical Association.

Listed below are a few select Arizona locations that have produced a number of valuable mineral samples. The history of the mines is as rich and varied as the minerals themselves.

The Christmas Mine, 75 miles north of Tucson in the Banner Mining District, was discovered in 1880. It was not until 1905 that production began due to challenges in transportation and processing. Over 80 minerals have been documented at Christmas Mine, including four type-local minerals (minerals representing the location where they were first documented and confirmed as a new mineral species). These include apachite, gilalite, junitoite, and ruizite.

Geophysical surveys and diamond drilling completed by Freeport-McMoRan Inc. over the past several years have confirmed mineral reserves at the Christmas Mine of approximately 332 million tonnes grading 0.40% copper, 0.0017 ounces per tonne gold and 0.032 ounces per tonne silver ton.

The Baghdad Mine in the Eureka Mining District of Yavapai County has been a copper producer since its discovery in the early 1880’s. Prospectors were drawn to the red and brown iron patches on exposed granitic porphyry rocks benefiting from widespread mineralization. The mine was operated with limited success in 1906 by the Giroux syndicate associated with JL Giroux, the former general manager of Senator William A. Clark’s Colusa mine in Butte, Montana.

Several companies followed, including Baghdad Copper Co. and Arizona-Baghdad Copper Co., who began mapping the orebody after conducting a series of churn holes. By 1926, ore was being leached on site. Block caving methods have been implemented to take advantage of the scattered lower grade copper occurrences.

JC Lincoln, President of Lincoln Electric Co., acquired the dominant stock of Baghdad Copper Corp. Under his leadership, mill capacity was improved and costs reduced, which included more consolidated stripping. Open pit mining began in 1945 and continues today under the direction of Freeport-McMoRan. Baghdad produced some notable mineral specimens, including cuprites with sharp, lustrous, well-defined red colored crystals. Other mineral samples include native copper, connellite and chalcotrichite.

The scattered San Manuel copper deposit is believed to be the largest underground copper mine in the world. Production occurred from 1956 until the mine closed in 2003. Total production of copper and molybdenum was 4,651,600 short tons and 73,200 short tons. Notable minerals include atacamite, copper, gold, and molybdenite.

Another mine of historical importance is the Iron Cap Mine, one mile north of Landsman Camp in the Santa Teresa Mountains. The Iron Cap Mine, a limestone substitute producer of silver, lead and zinc, was developed by the Athletic Mining Co. in 1942-1949. A 100 ton per day flotation concentrator built in 1949 processed lead and zinc ore. Collectible minerals found on site include manganese babingtonite, a calcium iron silicate hydroxide (similar to babingtonite with a higher concentration of manganese), along with axinite, johansite and nekoite.

Named for its discovery date in 1879 by Mike and Pat O’Brien, the Seventy Nine Mine saw sporadic production over the following decades as miners expanded the mine up a 55 degree incline to the 660 foot level. The on-site mills included crushers, elevators, screens and tables used to process the lead carbonate ores. The water pumped out of the shaft was used to operate the mill. Metals of commercial interest included lead and zinc ore. Lead ore was in the form of cerussite along with some anglesite and wulfenite and vanadinite. The mine is known to have produced many mineral samples including uncommon or rare secondary minerals such as descloizite, ktenasite, murdochite and plattnerite as well as fine samples of aurichalcite.

Red Cloud Mine is one of Arizona’s most renowned mineral wulfenite collection sites. In the late 1870s, ore was mined by the “single jack” method (miner driving a chisel into rock with a sharp steel point) and sorted and processed underground to a high grade, carried to the surface on miners’ backs and in rawhide pails, and transported by Burros to the Colorado River to be shipped by boat to Wales for processing. Operated by the Red Cloud Mining Co. for the next ten years, it mined profitably for lead, silver and zinc. Over the next century, the mine operated sporadically due to a fluctuating silver market. In the early 21st century, the mine became more accessible to collectors for a fee.