Apollo Silver (TSXV: APGO; US-OTC: APGOF) estimates initial capital of $633 million (C$888.3 million) for its Calico project in California, which could produce about 5 million oz. silver annually over 15 years.
A preliminary economic assessment released Thursday puts after-tax net present value at $737 million using a 5% discount rate, with a 25% internal rate of return at $55-per-oz. silver. The proposed open-pit operation would mine the Waterloo deposit, about 15 km northeast of Barstow in San Bernardino County.
“Our focus now is de-risking: studies on water, power and capital inputs are under way, and we are advancing toward a prefeasibility study,” CEO Colin Sutherland said in the release.
The assessment gives Apollo a development blueprint for a silver mine in the United States, with engineering, financing and permitting work still ahead. The economics rely on silver revenue alone, leaving the nearby Langtry deposit and Waterloo’s gold resource outside the mine plan.
Apollo shares fell 11% to C$1.70 by Thursday afternoon in Toronto, valuing the company at about C$107 million.
Price sensitivity
The study, prepared by SLR Consulting, proposes contract mining and an 8,000-tonne-per-day processing plant producing doré on site. It estimates total recovered silver production of 74.4 million oz., with all-in sustaining costs averaging $26.07 per payable ounce.
Higher-grade material would be processed first, averaging about 101 grams silver per tonne over the first decade. Some lower-grade material would be stockpiled for later treatment, with processing continuing through year 15.
Initial capital includes a 25% contingency, with total capital over the project’s life estimated at $715 million after sustaining spending, pit backfilling and closure costs. The study assumes two years of construction and an after-tax payback of three years from production startup. Capital estimates carry an accuracy range of 30% below to 50% above the stated figures.
Returns are sensitive to silver prices. At $45 per oz., after-tax net present value falls to $348 million and the internal rate of return drops to 16%. At $65 silver, those figures rise to $1.11 billion and 32%, respectively.
Recovery tests
The processing plan assumes 65% silver recovery, supported by laboratory testing on five Waterloo samples. Finer grinding improved recoveries, making that stage of the proposed plant important to achieving the study’s assumptions.
Apollo plans further testing to assess recovery across different types of mineralization and refine processing. The plant design includes filtered, dry-stack tailings to recycle most process water.
Water rights would need to be acquired or leased within the Mojave Basin. Apollo must also confirm a power connection, including available capacity on nearby transmission lines.
Although Waterloo and Langtry lie on private land with county-recognized vested surface mining rights, Apollo hasn’t obtained the permits needed to construct or operate the project.
The company expects permitting to proceed mainly under California environmental and reclamation laws, with San Bernardino County as lead agency. Federal environmental review could also apply if a project component requires a federal permit or federal funding is used. Environmental baseline studies are planned for next year.
Resource revision
An updated estimate effective Oct. 1 puts Waterloo’s resource at 42.2 million measured and indicated tonnes grading 85.1 grams silver per tonne for 115.6 million ounces. Another 1.1 million inferred tonnes grading 65.4 grams contain 2.3 million ounces.
Langtry holds 23 million inferred tonnes grading 66.3 grams silver for 49.1 million oz., excluded from the proposed operation.
Waterloo’s measured and indicated silver inventory declined 7.5% from 125 million oz. in the June 2025 estimate, while tonnage decreased 23% and average grade increased 20%. The update uses the same drilling database, with changes reflecting revised estimation methods, classification, prices, costs and reporting cut-offs. Barite and zinc are excluded, and gold is reported separately.
Apollo’s next work includes metallurgical and geotechnical drilling, water and power arrangements and environmental studies ahead of a prefeasibility study. The company expects to file the supporting technical report for the assessment by Dec. 13.
Source: www.northernminer.com — article syndicated from the publisher’s feed; all rights remain with the original publisher.
