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Geologic mapping has always been an important function of AZGS and its predecessors. Since the introduction of two cooperative mapping programs between the U.S. Geological Survey and state geological surveys (COGEOMAP in 1985 and STATEMAP in 1993), AZGS has conducted detailed geologic mapping every year. The initial focus was 1:24,000-scale mapping of areas where substantial development and population growth were occurring, prioritizing the Phoenix-Tucson metropolitan corridor. In recent years, our mapping has included areas of interest in addressing mineral and aggregate resource issues, geologic hazards potential, and scientific research. 

Arizona has a diverse array of metallic mineral resources. The largest and most-well known producing mines exploit very large, low-grade porphyry copper deposits. In recent years Arizona has consistently lead copper production in the United States (accounting for ~70% of total domestic output in 2025). Additional deposit types in Arizona include pegmatites, uranium breccia pipes and sediment hosted deposits, skarn and carbonate replacement deposits, shallow epithermal and vein hosted mineralization, and more! Our team is devoted to researching Arizona’s mineral resources and critical mineral potential through detailed deposit studies, regional geochemical and geochronologic reconnaissance, and producing county mineral resource reports. 

When mineralized rock is mined to produce a commodity such as copper, gold, silver, lead, or zinc, only a small percentage of the material extracted is ore; the rest is waste. After the rock is crushed and ore minerals are extracted for further processing, the remaining material is deposited in large rock piles or as a sandy slurry called “tailings”. Because recovery is imperfect and some material is below cutoff grades, ore minerals can end up in the tailings and waste rock piles, reaching economically viable concentrations over time. As the societal demand for raw materials increases and puts additional strain on our supply chains, focus is shifting to reprocessing tailings to extract ore that may have been lost during the initial mining and milling process.

Because of Arizona’s prolific mining history, millions of tons of mine waste can be found across the state, but a lot of work has to be done before waste can be reprocessed. The first step is locating this waste and using geological and technical reports to determine what the source material was and what elements are likely to be present. The second step is sampling, so we can analyze the elemental and mineralogical constituents. The third step is finding economically feasible methods and technologies to recover elements from mined material. 

AZGS has been awarded federal funding through the USGS Earth MRI program to locate, sample, and analyze tailings features in Arizona, while other departments within the University of Arizona are researching methods to extract commodities from the waste. The benefits of reprocessing mine waste are twofold: we can recover valuable elements, reducing the strain on active mining and supply chains while simultaneously removing mine waste from the landscape to lessen its impact on communities and the environment. Additionally, some researchers are working to develop fertilizers and building materials from the waste after valuable elements are recovered. Though we are still a long way from full-scale reprocessing and removal of tailings, this field of study is advancing rapidly and shows great promise.

Through support from the U.S. Geological Survey’s National Geologic and Geophysical Data Preservation Program (NGGDPP), the Arizona Geological Survey has invested substantial effort into preserving geologic and mining related data and resources that may otherwise be lost in the digital age. Key resources preserved include geologic maps, drill hole logs and assays, mining records, and original research otherwise not previously available to the public. 

If you or your company has Arizona-specific geologic or mining files, please consider donating to AZGS! Email: azgs-info@email.arizona.edu