Three of the world's major mining companies are lending their financial weight to junior explorers developing copper projects across the U.S. Southwest, while a fourth junior is working to position itself as a domestic producer of antimony and gold.

Teck Resources (TSX: TECK.A/TECK.B; NYSE: TECK) holds a stake in Intrepid Metals (TSXV: INTR; US-OTC: IMTCF), Rio Tinto's (NYSE, LSE, ASX: RIO) Nuton division is funding Lion Copper & Gold's (CSE: LEO; US-OTC: LCGMF) Yerington project, and Newmont (TSX: NGT; NYSE, ASX: NEM) owns 9.2% of Metallic Minerals (TSXV: MMG; US-OTC: MMNGF).

NevGold (TSXV: NAU; US-OTC: NAUFF), for its part, is evaluating an accelerated pathway to antimony production in Nevada.

The pattern reflects copper's central role in electrification, with demand driven by electric vehicles, power grids and data centres, and it comes as the U.S. government works to shore up domestic supply of copper and other minerals designated as critical to the economy and national security. For the seniors, backing juniors offers early exposure to new deposits at a time when discoveries are scarce and mine supply is concentrated in a handful of producing countries.

Intrepid Metals

Intrepid Metals is exploring its pre-resource Corral copper property in southeastern Arizona with the backing of Teck Resources, which holds a 9.9% interest in the junior.

The company acquired Corral in 2023 on the strength of its potential to host near-surface carbonate-replacement copper-gold-silver mineralization together with a related porphyry copper-gold system.

The geological model invites comparison with Arizona's historic Bisbee copper camp, roughly 100 km to the southeast, where high-grade carbonate-replacement mineralization occurs alongside the Lavender Pit porphyry deposit. Arizona has long been a cornerstone of U.S. copper output, and the Southwest hosts some of the country's most prospective ground for new porphyry-related discoveries.

In July, Intrepid identified a new porphyry target named Curly and plans to begin 10,000 metres of drilling in September, divided between porphyry targets and previously identified carbonate-replacement mineralization.

Drilling last year reinforced the project's promise. Hole CC25-040 at the Clanton zone returned 71.7 metres grading 0.8% copper, 0.1 gram gold per tonne, 5.35 grams silver and 0.46% zinc starting from 47.2 metres depth, including a higher-grade interval of 24.35 metres running 2.19% copper, 0.17 gram gold, 11.59 grams silver and 1.05% zinc.

Intrepid holds additional projects elsewhere in Arizona and carries a market capitalization of $97.6 million.

Lion Copper & Gold

Lion Copper & Gold is advancing the Yerington copper project in Nevada, which encompasses the past-producing Yerington and MacArthur mines located about 113 km southeast of Reno.

Rio Tinto's Nuton division is funding the project under an option to earn a 65% interest. Nuton has developed proprietary leaching technologies designed to recover copper from primary sulphide resources. Such technology is aimed at deposits that conventional processing handles less efficiently, and its deployment at Yerington would be among the larger-scale applications of the approach if the project proceeds.

Lion aims to complete a definitive feasibility study in the first quarter of next year and is targeting first production in the first half of 2030.

A prefeasibility study completed last year outlined average annual output of 120 million lb. refined copper cathode over a 12-year mine life, with all-in sustaining costs estimated at $2.67 per pound.

The study pegged post-tax net present value at $694 million (C$968 million), based on a 7% discount rate and a copper price of $4.30 per lb., with an internal rate of return of 15%. Initial capital was estimated at $724 million.

Yerington hosts 459.5 million proven and probable tonnes grading 0.21% total copper, containing 2.14 billion lb. of copper.

In August, Lion substantially expanded the project's inventory with an initial resource at Bear, which contains about 1 billion indicated tonnes grading 0.29% copper for 6.7 billion lb. of copper, plus 1.7 billion inferred tonnes grading 0.22% copper for 8.7 billion pounds.

Lion Copper & Gold has a market capitalization of about C$116 million.

Metallic Minerals

Metallic Minerals is advancing its La Plata copper-silver-gold-PGE project in southwestern Colorado.

An updated resource published this year at the Allard porphyry deposit outlined 181.4 million inferred tonnes grading 0.33% copper and 2.9 grams silver, containing 1.3 billion lb. copper and 17 million oz. silver.

A 45.4-million-tonne subset of the resource also carries platinum, palladium and gold, grading 0.06 gram platinum, 0.08 gram palladium and 0.04 gram gold for 91,000 oz. platinum, 121,000 oz. palladium and 60,000 oz. gold.

Across the 44-sq.-km property, situated at the southwest end of the Colorado Mineral Belt, Metallic has identified 16 untested potential porphyry centres. The Colorado Mineral Belt is a historic mining corridor that has produced gold, silver and other metals since the 19th century, and its porphyry systems remain a focus of modern exploration.

In July, La Plata was chosen as one of two test systems for a U.S. Department of Energy-funded program developing AI-assisted critical-minerals exploration technology.

Newmont has been a strategic shareholder since 2023 and owns 9.2% of Metallic. The junior has a market capitalization of $60.1 million.

NevGold

NevGold intends to become a U.S. producer of antimony and gold from its Limousine Butte project in eastern Nevada.

Antimony is on the U.S. critical minerals list, with supply dominated by China, and the metal is used in flame retardants, ammunition and other applications. Potential domestic production has drawn policy attention as Western governments seek to reduce import dependence.

The 70-sq.-km brownfield project, about 80 km north of Ely, previously hosted the Golden Butte open-pit heap-leach operation in the late 1980s.

In July, NevGold published the first resource estimate at Limousine Butte in more than 17 years. Measured and indicated resources total 15.2 million tonnes grading 0.37 gram gold, 1.15 grams silver and 0.21% antimony, for 181,400 oz. gold, 562,200 oz. silver and 31,800 tonnes antimony.

Inferred resources add a further 117.5 million tonnes grading 0.32 gram gold, 0.61 gram silver and 0.09% antimony, containing 1.2 million oz. gold, 1.69 million oz. silver and 75,700 tonnes antimony.

NevGold plans 20,000 metres of drilling this year focused on converting and expanding resources and on follow-up work at the high-grade Bullet Zone and Armory Fault discoveries.

The company is also weighing an accelerated route to production that would involve processing material from historic leach pads before transitioning to larger-scale commercial mining and processing in 2029-30.

NevGold has a market capitalization of $322.8 million.