Minerals 260 (ASX:MI6) reported an updated mineral resource estimate for its Bullabulling gold project in Western Australia of 190 million tonnes at 1 gram per tonne grade of gold for 6.2 million ounces, an increase of 38% from the December 2025 estimate of 4.5 million ounces, according to a Wednesday filing with the Australian bourse.
The updated estimate, which incorporates 345 new drill holes, will be incorporated into a revised ore reserve estimate planned for completion alongside a definitive feasibility study scheduled for the first quarter of calendar 2027, per the filing.
The company said 71% of the updated mineral resource estimate is classified as indicated, a 47% increase from the previous estimate.
In a separate same-day filing, Minerals 260 said it completed a pre-feasibility study and a maiden ore reserve for the Bullabulling project. The pre-feasibility study shows "compelling economic outcomes" with a net present value of AU$2.3 billion, an internal rate of return of 43%, average annual free cash flow of AU$330 million, and earnings before interest, taxes, depreciation, and amortization of AU$510 million.
The pre-feasibility study also describes the production of 150,000 ounces of gold per year at an all-in sustaining cost of AU$2,520 per ounce, as well as a 19-year operating life with production starting in the fourth quarter of calendar 2028.
Meanwhile, the project's maiden ore reserve estimate of 90 million tonnes at 0.86 g/t gold for 2.5 million ounces makes it the "largest undeveloped gold reserve in Australia not owned by an existing producer," the company said.
Minerals 260 shares fell nearly 6% in recent Wednesday trade.