Minera Alamos greenlights Copperstone gold mine in Arizona

Minera Alamos (TSXV: MAI) said it will proceed with construction of the past-producing Copperstone underground gold mine in Arizona, a $58 million investment that the company says will be recouped in barely one year.

Copperstone could produce about 46,000 oz. of gold annually over a six-year mine life, more than doubling the company’s consolidated output, Toronto-based Alamos said late Wednesday in a statement as it released a new pre-feasibility study (PFS). Annual production is about 13% higher than what the company had envisaged in a March 2025 preliminary economic assessment.

“We view the PFS positively, as the mine life is longer than our current model with additional resource upside, and costs are in line with expectations,” Desjardins Capital Markets mining analyst Allison Carson said Thursday in a note.

Key asset

Though a relatively mid-sized operation, Copperstone is a key asset in the company’s drive to build a diversified North American gold producer with multiple low-capital operations. Alamos operates the Pan and Gold Rock mines in Nevada, as well as the Santana mine in Mexico. It’s also advancing the Cerro de Oro and La Fortuna projects in Mexico.

At a gold price of $3,500 per oz., using a 5% discount rate, Copperstone has an after-tax net present value (NPV) of $374 million, an internal rate of return (IRR) of 108% and a payback period of 1.2 years, the study shows. If a spot gold price of $4,500 is used, the NPV rises to $537 million while the IRR jumps to 154% and the payback period shrinks to about 10 months.

Construction is expected to take about 12 months, with first production targeted for mid-2027 at an all-in sustaining cost of $1,314 per oz., Alamos said. Sustaining capital expenditures once the mine opens are pegged at $77 million.

Capital expenditures associated with Copperstone will be financed by the company’s existing cash balance, excess capacity under a $75 million revolving credit facility and ongoing cash flow from the Pan mine, Alamos said. Cash reserves stood at $46 million as of the end of March.

Prolific belt

Located about 230 km west of Phoenix, near the California border, Copperstone hosts a high-grade underground gold deposit along the Walker Lane structural trend, a prolific mineral belt that extends through Nevada, California and Arizona. The project covers 37 sq. km and includes extensive underground development, processing infrastructure and existing permits.

Discovered in 1979, Copperstone was operated as an open-pit mine by Cyprus Minerals in the 1980s before Sabre Gold bought the asset in 2014. Alamos inherited the property when it acquired Sabre in February 2025.

Management has spent the past year updating engineering plans and revising permit applications aimed at expanding the operation beyond the original mine plan. Alamos has also identified exploration opportunities near existing workings and in satellite zones surrounding the main deposit.

Upside potential

Copperstone holds about 4.1 million measured and indicated tonnes grading 4.83 grams gold per tonne for contained metal of 630,000 oz. gold, according to an updated resource dated Dec. 1. Inferred resources were pegged at 401,000 tonnes grading 4.04 grams gold for contained metal of 52,000 ounces.

“We continue to expect upside at Copperstone as the reserve only represents half of the measured and indicated resource,” Carson said. “There also continues to be down-plunge extension potential that will be drilled from underground. In addition, there is open-pit potential, which could potentially boost production through a standalone heap-leach operation.”

Shares of the company fell 1.1% to C$7 in Thursday morning trading in Toronto, valuing Alamos at about C$756 million ($546 million).

Alamos has proposed changing its name to Mining Americas, subject to shareholder approval at the company’s annual general meeting on June 25.