Capricorn Metals Ltd (ASX: CMM) has released an updated pre-feasibility study (PFS) for its Mt Gibson gold project in Western Australia, significantly expanding the project’s production profile and mine life. The updated study marks a milestone by incorporating underground mining for the first time, which is expected to ramp up annual production to 260,000 ounces.

The study outlines a 19.25-year mine life, with total production forecast at 3.5 million ounces of gold at an all-in sustaining cost of A$1,870 per ounce. Financial projections for the project include a post-capex, pre-tax net present value of A$6.1 billion, underpinned by a rapid 14-month pre-tax payback period. Total development capital is estimated at A$345 million for the processing plant and infrastructure, with an additional A$129 million allocated for pre-production mining.

"We are delighted to deliver the updated Mt Gibson PFS incorporating underground production for the first time. The study highlights the exceptional quality and longevity of the Mt Gibson project with production ramping up to 260,000 ounces per annum and compelling economics that confirm it as one of the most exciting development opportunities in the Australian mid-tier gold sector."

"Having now validated the strong technical and financial viability of underground mining at Mt Gibson we also look forward to investigating how that growing inventory and the broader opportunities on the tenure package including Golden Range can be best optimised to deliver value for Capricorn shareholders."
— Mark Clark, Executive Chairman

The project’s resource and reserve base has seen substantial growth compared to 2025. The updated mineral resource now stands at 5.67 million ounces, a 20% increase in contained gold, while ore reserves have climbed 34% to 3.67 million ounces. A key driver for this shift is the inclusion of a maiden underground reserve of 5.0 million tonnes at 2.3 g/t gold for 365,000 ounces, replacing earlier conceptual work from 2025 that was at a much earlier stage of development.

Following recent federal environmental approvals, Capricorn is moving quickly toward construction. The company plans to initiate procurement for major processing equipment and contracts in Q1 FY27, with site development activities currently targeted for Q2 FY27. Beyond the primary development, technical studies are already underway for a potential "Stage 2" at the Golden Range area, with preliminary results on plant scale options expected in the second quarter of the 2027 fiscal year.

Management remains focused on advancing the project through formal feasibility and final investment decision stages, which are anticipated in calendar year 2027. By integrating the new underground component alongside open-pit operations, the company aims to solidify Mt Gibson’s position as a long-life, high-margin asset. The current study confirms that 96% of the production outlined in the mine plan is derived from existing ore reserves, providing a clearer operational path forward as the project transitions from the development phase to expected production.

Read the full announcement: Compelling Mt Gibson PFS Update