Gunnison Copper’s Johnson Camp Mine Near Tucson, Arizona: Set to Be First New U.S. Copper Production in a Decade: It Utilizes Nuton’s Bioleaching Technology, as Do Other Projects in the Region

     Copper is one of the new minerals put on the updated USGS critical minerals list for 2025. The U.S. has not had new copper production in a decade, and a new, or rather a revitalized, mine reopening very soon will change that. Gunnison Copper’s Johnson Camp Mine near Tucson is expected to begin production in the coming days. Production ceased at the mine in 2010 when the copper ore grade was deemed too low in concentration to produce. However, newer extraction methods are expected to revitalize production. The mine restart, in collaboration with Rio Tinto’s Nuton venture, will utilize microbes and an acid solution to extract the copper and then transform it into cathodes.

     Arizona already produces 70% of U.S. copper. It has a long history of successful copper mining. Now, the state is at the forefront of domestic copper production revitalization.

     The Wall Street Journal’s Ryan Dezember, who wrote a nice article about the mine, notes:

“Gunnison started selling cathodes made using conventional heap-leaching methods of Johnson Camp’s oxide ores in September. The first batch of copper extracted from its sulfide ores using the Nuton technology is expected in the coming days. Ramped up, Johnson Camp should annually produce 25 million pounds of cathode.”

     While it is very true that domestic copper production can benefit from tariffs on imported copper, already at high levels, those tariffs harm buyers and consumers. Copper prices have risen since U.S. tariffs were enacted, but had been rising for years, as shown below.

     The U.S. has abundant low-grade copper ores, but it remains challenging to produce them economically. Nuton’s bioleaching technology is being utilized to extract copper from low-grade ore in new ways.

     Dezember goes on to talk about the very long times it takes to build a mine, to get from discovery to production, which I wrote about recently here, and the need to reduce those timeframes. Some projects in the region have been fighting legal challenges for more than a decade.

     Taseko Mines is trying a different approach at its Florence project southeast of Phoenix, which is utilizing a technique of uranium miners and pumping acid down into wells to separate the copper below the surface, known as an in-situ method. Taseko expects Florence to eventually produce about 85 million pounds of cathode per year.

“Of all the copper that exists in the ground globally, 70% of those resources are comprised of primary sulfides, this mineralogy that we’re looking to unlock,” said Nuton chief executive Adam Burley. “That size of prize is enormous.”

     Taseko has been exploring the idea of in situ mining methods for thirty years, but only now is moving toward production.

“The Nuton name plays on Isaac Newton, the alchemist, as well as the hunt for “a new ton” of copper, which had become elusive via deal or discovery, Burley said.

“We needed a different model because the one that we’d been trying for years wasn’t delivering the results we wanted,” said Clayton Walker, who is responsible for the growth and development of Rio’s copper business in the Americas.

     The Johnson Camp mine is a good place to test the Nuton bioleaching process since it already has two key components: a heap leach pad and a solvent-extraction electrowinning plant, where the copper dripping in solution from the ore is plated onto the cathodes.

     The sulfide ores are crushed, coated with bacteria and acid, then piled onto a new heap leach pad. 

     Nuton also has partnerships with several other copper mines in the region. The company also plans to reopen a copper mine that closed in 1984 and apply the process. This is Arizona Sonoran Copper’s Cactus project. It expects to begin construction in 2027 with the first cathodes made in 2029. That is extremely quick in terms of mining times and underscores the advantages of revitalizing older works over new projects in terms of time to production.

 

     

References:

 

Can Arizona Miners Unleash an American Copper Boom? Ryan Dezember. Wall Street Journal. December 2, 2025. Can Arizona Miners Unleash an American Copper Boom?