FIREWEED METALS CORP. announced a new mineral resource estimate for its Mactung Project located in Yukon and Northwest Territories, Canada, within the Traditional Territories of the Kaska Dena Nation and First Nation of Na-Cho Nyäk Dun, and the Sahtú Settlement Area. The current Mineral Resource at Mactung ranks it the largest high-grade tungsten resource in the world and it is a clear statistical outlier in terms of grade and contained metal.

It is a tungsten skarn deposit associated with Tombstone-Tungsten suite granitic intrusions that are more broadly linked to a variety of gold and tungsten deposits across Yukon-Northwest Territories. The Mactung deposit is sub-divided into an upper and lower zone that both occur at surface and extend to depths of approximately 400 m below surface. A very high-grade portion of the resource was constrained by underground mining volumes at a 0.5% WO3 cut-off grade, within the gently to moderately dipping, roughly tabular, lower zone that is approximately 20-30 m thick, extending for a kilometre in strike and up to 380 m down-dip.

In the upper zone, a high-grade open pit resource was constrained by a conceptual pit shell at a 0.25% WO3 cut-off grade. The Mineral Resource estimate considers and employs reasonable prospects for eventual economic extraction, is applied within classification domains that are continuous, and uses a classification scheme involving a drill spacing that was based on drill-spacing studies. Additional bulk density and assay data were collected during an extensive Fireweed campaign of re-sampling historic drill core in late 2022 and early 2023, and a new geological interpretation of the deposit has been made.

These factors have resulted in a robust estimate of the Mineral Inventory at Mactung, providing a solid foundation for future mine development studies. Copper and gold were estimated as by-product metals for underground constrained resources only No metallurgical test work has been conducted to assess the recovery of copper or gold at Mactung. Based on historical production of small quantities of gold and of copper concentrate from the geologically similar Cantung mine†, it has been reasonably assumed that gravity separation and a copper circuit could be incorporated into the flowsheet to recover a portion of the gold and copper in the Current Mineral Resource to satisfy the reasonable prospects of eventual economic extraction.

Fireweed and its consultants are currently completing metallurgical test programs to validate the recovery of tungsten and assess the recovery of gold and copper at Mactung. Grades of copper and gold were considered too low to include within the Mineral Resource Statement for open-pit constrained resources. The cut-off grades of 0.5% WO3 for underground mining and 0.25% WO3 for open-pit mining were selected based on a tungsten concentrate price assumption of approximately USD$240/mtu, supported by updated estimates from trading companies that specialize in tungsten, and preliminary estimates of operating costs.

Reasonable prospects for eventual economic extraction of the mineral resources, as required by NI43-101, were demonstrated by developing underground constraining volumes, conceptual pit shells using a Lerchs-Grossman algorithm and input parameters derived from preliminary cost estimates. Only mineral resources above these cut-offs and within the mineral resource-limiting underground constraining volumes and pits are reported; mineralization falling below this cut-off grade or outside the resource-limiting volumes or pits is not reported, irrespective of the grade. Potential underground resources are constrained initially to only the lower zone (2B unit) and a portion of the upper zone (3D unit) below the pit shell leaving a crown pillar.

The potential open-pit resource was optimized for only the upper zone (3C, 3D, 3E, 3F, 3G and 3H units). Gold and copper are considered by-products and were not utilized in cut-off grades, pit optimizations, underground constraints, or for establishing reasonable prospects of eventual economic extraction.