Resolution Minerals Limited (ASX: RML) (“Resolution” or the “Company”) has announced a significant milestone in advancing its Antimony Ridge prospect, part of the Company’s broader Horse Heaven Antimony-Tungsten-Gold-Silver Project in Idaho, USA. The Company has successfully produced a high-purity antimony trioxide product from stibnite samples, marking a critical step towards establishing a robust downstream processing pathway.
This achievement reinforces the strategic importance of Antimony Ridge, particularly as global demand for secure and high-purity antimony supply continues to grow amid tightening geopolitical conditions.
Figure 1: Location of the Horse Heaven Project within Idaho and the location of the Antimony Ridge within Horse Heaven [Resolution Minerals]
Figure 2: Antimony Ridge, within Resolution’s broader Horse Heaven Antimony–Tungsten–Gold–Silver Project, highlights the spatial and geological relationship between the antimony (Sb) mineralisation at Antimony Ridge and the adjacent Golden Gate gold (Au) and Golden Gate tungsten (W) zones. [Resolution Minerals]
High-Purity Antimony Trioxide Achieved
The Company confirmed that metallurgical test work conducted by Kingston Process Metallurgy (KPM) in Ontario successfully produced an intermediate antimony trioxide product with an impressive purity of 99.38 wt% Sb₂O₃.
This result stems from conventional pyrometallurgical processing using volatilisation, a widely accepted industry method for refining antimony-bearing ores such as stibnite. Importantly, the product showed minimal impurities, highlighting the quality of the feed material and the effectiveness of the process.
Adam Roper, PhD, Resolution’s In-house Senior Metallurgist, stated:
“The initial pyrometallurgical results from processing Antimony Ridge samples are very encouraging, with few impurities. This is a great start, and I’m looking forward to discussing the final results in the coming weeks.”
The Company continues to further refine test work, with final product results expected shortly.
Dual Processing Strategy: Pyrometallurgy and Hydrometallurgy
Resolution is progressing a dual-track metallurgical strategy to optimise processing efficiency and scalability. While pyrometallurgy currently forms the base-case approach, the Company is also advancing hydrometallurgical test work through Australia’s ANSTO.
This dual approach provides flexibility in selecting the most economically and environmentally viable processing route, especially as regulatory scrutiny around antimony processing intensifies globally.
In parallel, concentrate test work is underway at IMO laboratories in Perth, targeting the efficient recovery of antimony alongside tungsten and gold.
Adam Roper further added:
“Resolution’s goal is to develop a processing hub in Idaho for stibnite and I’m relishing the opportunity to bring this to fruition, from mine to product.”
Strategic Push for US Processing Hub
A key pillar of Resolution’s strategy is to establish a hydrometallurgical processing hub in Idaho. This initiative addresses the current lack of modern antimony processing infrastructure in the United States.
The Johnson Creek Mill site, located at the base of Antimony Ridge, presents a compelling opportunity for rapid development due to its existing infrastructure, including power, water, and private land ownership.
Adam Roper highlighted the potential:
“The Johnson Creek Mill site, at the base of Antimony Ridge, is being considered as a fast track option for potential development of a local processing site, given it has the necessary infrastructure on site, with power and water, and is on 10 acres of private land owned 100% by RML.”
This aligns with broader Western efforts to localise critical mineral supply chains, particularly following China’s export restrictions in late 2024, which significantly disrupted global antimony markets.
Expanding Resource Potential Through 3D Modelling
Beyond metallurgy, Resolution has made strong progress in defining the scale of Antimony Ridge. Recent 3D modelling has identified extensive vein swarms and stockworks across a large footprint of approximately 1,000m x 700m, suggesting substantial exploration upside.
These high-grade antimony-bearing stibnite veins have consistently returned grades exceeding 30% Sb, with peaks up to 50% Sb in recent results.
The scale and continuity of mineralisation indicate the potential for a significant antimony-silver system, open in multiple directions.
Figure 3: Resolution Minerals has successfully generated an antimony trioxide product from bulk stibnite samples sourced from the historic Antimony Ridge open pits, using established pyrometallurgical processing methods. An image displays a representative sample of the produced antimony trioxide. [Resolution Minerals / LinkedIn]
Historical Significance and Strategic Location
Antimony Ridge holds historical importance as a key contributor to the US antimony supply during World War I, World War II, and the Korean War. The broader district once produced over 90% of the United States’ antimony, underlining its strategic value.
Today, the Project sits adjacent to a major permitted antimony-gold operation, reinforcing its potential as a cornerstone asset in revitalising domestic supply chains.
FAST-41 Recognition Accelerates Development
In a major regulatory boost, the Horse Heaven Project has been selected for the US FAST-41 Transparency Coverage. This designation is expected to streamline permitting timelines and support the Company’s ambitious development plans, including:
- Up to 250 drill holes
- Large-scale bulk sampling programs
- Expanded exploration campaigns
Managing Director Ari Zaetz commented:
“With the recent US Government Permitting Council provided via FAST-41 Coverage to accelerate permits, Resolution is in parallel developing further local processing plans to enable antimony and tungsten supply for US demand. Our unique combination of critical minerals assets makes us well placed to deliver.”
Antimony Market Outlook: Strategic Metal in Focus
The timing of Resolution’s metallurgical success coincides with strengthening fundamentals in the global antimony market.
According to Mordor Intelligence, the antimony market is projected to grow from 129.12 kilotons in 2026 to 140.27 kilotons by 2031, driven by applications in:
- Energy storage systems
- Semiconductor manufacturing
- Defence electronics
China’s dominance in supply and its recent export restrictions have exposed vulnerabilities in global supply chains, prompting Western nations to prioritise domestic production.
Notably, antimony trioxide, like the product produced by Resolution, accounts for over 56% of global demand, particularly in flame retardants and advanced materials. This positions Antimony Ridge favourably within evolving market dynamics.
Future Plans and Exploration Upside
Resolution is gearing up for an extensive development phase in 2026, including:
- Bulk sampling of high-grade antimony ore
- A major drilling program at Golden Gate (up to 45,000 feet)
- Continued metallurgical optimisation
These initiatives aim to define a maiden Mineral Resource and unlock the full value of the Horse Heaven Project.
Figure 4: Antimony Ridge – Historic open pits and trenches dating back to World Wars I & II and the Korean War, with visible access roads, shown in a 3D satellite view facing northeast. [Resolution Minerals]
Investors’ Outlook
Resolution Minerals is steadily transitioning from exploration to development, underpinned by strong metallurgical results and strategic positioning in the critical minerals sector.
The Company’s recent share price performance reflects growing investor confidence:
- Last Price: $0.065
- Change: +6.56%
- 1 Week: +41.30%
- 1 Month: +14.04%
- 2026 YTD: +32.65%
- 1 Year: +828.57%
- Market Cap: $136.33 million
Figure 5: Resolution Minerals’ exceptional share price performance in the last month [Colitco]
With high-grade mineralisation, advancing metallurgical pathways, and strong regulatory support via FAST-41, the Company is well-placed to capitalise on the tightening global antimony supply landscape.
As demand shifts towards secure, high-purity sources, Resolution’s integrated strategy, from mine to processing hub, positions it as a potentially significant player in the Western critical minerals supply chain.
Disclaimer: This editorial is provided for informational purposes only and is based on publicly available information at the time of writing. It does not constitute financial product advice, investment advice, or a recommendation to buy, sell, or hold any securities. While reasonable care has been taken to ensure the accuracy and reliability of the information presented, no guarantee is made regarding its completeness or correctness. Readers should conduct their own independent research and seek advice from a licensed financial adviser before
Last modified: April 17, 2026
