Felix Gold (ASX: FXG) has reported that recent metallurgical test work on high-grade stibnite veins from its Treasure Creek project in Alaska has delivered military-grade antimony concentrate using only a single flotation pass, validating multiple processing pathways and underscoring the project’s strategic importance to US supply chains.
The results show flotation feed containing 89.2% antimony-bearing minerals and an exceptionally low impurity profile, enabling concentrate grades of up to 74% antimony—above the 70% minimum required under the US military specification MIL-A-22131.
Executive director Joe Webb said the natural purity of the mineralisation represents “a geological outlier,” giving the US a rare domestic antimony source at a time when supply chain security is a national priority.
Ultra-High Grades Enable Simple Processing
The bulk metallurgical samples tested at Treasure Creek’s NW Array prospect contained 57.3% stibnite and 31.9% antimony oxides, with gangue minerals making up less than 10% of the material.
Because of this purity, a simple rougher flotation using standard commodity reagents delivered military-spec concentrate without the need for complex multi-stage upgrades.
Flotation also produced an ultra-low impurity profile, with arsenic below 0.1% and lead, copper and zinc all below detection limits, giving the concentrate potential for downstream semiconductor-grade refinement.
Direct alkaline sulphide leach testing achieved 98% extraction, providing an alternative hydrometallurgical pathway that could bypass traditional smelting.
A third route — X-ray transmission ore sorting — has been identified as a potential pre-concentration or direct-shipping option, although Felix has not yet completed test work for this method.
Strategic Significance for US Supply
Felix highlighted that the US is nearly 100% import-dependent for antimony, with no domestic mine production for more than 30 years.
China and Russia collectively control more than 90% of global supply, and China’s 2024 ban on antimony exports to the US has intensified domestic demand for new secure sources.
The company said Treasure Creek’s ability to produce military-grade concentrate with minimal processing positions it favourably within the context of recent US Government initiatives aimed at strengthening domestic production of critical minerals.
“The ore’s natural purity changes everything—the mining footprint, the processing simplicity, reduced capital requirements, and the speed at which you can produce high-grade material,” Mr Webb said, adding that a domestic, high-purity antimony system provides “a genuine pathway to supply chain resilience.”
He said Felix is moving quickly to advance its streamlined development strategy, with stockpiling expected to commence shortly and a view toward supplying defence, semiconductor, clean energy and industrial markets.
Further Technical Work Necessary
Felix emphasised that — with no feasibility study completed — production scenarios remain conceptual until it has finalised further technical work and permitting.
The company will undertake further flotation optimisation, including oxide flotation to improve overall recovery from tailings and refinement of reagent use and operating costs.
Hydrometallurgical optimisation will include alkaline leach refinement, scale-up testing and electrowinning trials to evaluate potential direct production of antimony metal.
Felix will also conduct XRT ore-sorting test work, evaluate pre-concentration opportunities and assess gold recovery from concentrates and tailings.
The scheduled drilling for 2026 will supply broader geometallurgical samples to better define deposit-wide variability and support future engineering studies and mine planning.
