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IRIS Metals Limited (ASX:IR1) has initiated Phase I exploration at its Finley Basin Tungsten Project in western Montana, USA, advancing efforts to validate historic tungsten mineralisation first identified by Union Carbide decades ago. Following an extensive review of legacy exploration data, the company is preparing for its inaugural diamond drilling campaign slated for Q3 2026, pending permit approvals. This project enhances IRIS’s North American critical minerals strategy by incorporating tungsten alongside its existing lithium and critical minerals assets.
Key Points
- IRIS Metals Limited (ASX:IR1) focuses on critical minerals exploration in North America, operating in South Dakota and Montana.
- Field activities have commenced at the Finley Basin Tungsten Project, including surface sampling, geological mapping, and ultraviolet lamping to detect scheelite mineralisation.
- A Phase I diamond drilling program of up to 7,000 metres across 16 drill sites is planned, with drilling expected to start in Q3 2026 subject to permit approval.
- Historical exploration by Union Carbide identified an estimated mineral reserve of 850,000 tons at 0.68% WO3 from 10 drill holes; this is a historical estimate not compliant with JORC Code and has not been independently verified by IRIS.
- Investors should monitor permit approvals in Q3 2026, drilling commencement, and initial assay results anticipated in Q4 2026.
IRIS Metals Advances North American Tungsten Exploration with Finley Basin Project
IRIS Metals Limited has begun exploration at the Finley Basin Tungsten Project, marking a key milestone in expanding its critical minerals portfolio beyond lithium in South Dakota to include tungsten in Montana. Located approximately 16 kilometres east-northeast of Philipsburg within the Flint Creek mountain range, the project sits at elevations between 2,100 and 2,300 metres, benefiting from established infrastructure and year-round access critical for exploration progress.
Tungsten’s strategic importance is underscored by its growing applications in defence, aerospace, energy, electronics, and advanced manufacturing. As global demand rises and Western governments prioritize secure critical mineral supply chains, the Finley Basin Project is well-positioned to contribute to North America’s tungsten supply resilience. This new tungsten exposure complements IRIS’s lithium assets, diversifying its critical minerals portfolio and reducing operational concentration risk.
Historical Data Review Informs Maiden Drilling Campaign
IRIS has completed a detailed assessment of Union Carbide’s late 1970s to early 1980s exploration data, which included 14 drill holes within the Finley Basin area. Union Carbide’s historical estimate indicated a mineral reserve of 850,000 tons at 0.68% WO3 based on 10 drill holes in the mineralised core. IRIS notes this estimate originates from a February 1983 report and is not compliant with the JORC Code (2012 Edition); it has not been independently verified and is not reported as a current resource.
This review enabled IRIS to identify previous access tracks and drill pads, minimizing environmental impact and aiding permit applications. The planned drilling will target scheelite mineralisation within the Amsden Formation and the tactite horizon at the base of the Madison Formation. While IRIS has found no reason to doubt the historical data’s reliability, it does not endorse it as current resource information.
Ongoing Field Work Includes Surface Sampling and UV Lamping
Field activities commenced in June 2026, involving systematic surface sampling, geological mapping, and nighttime ultraviolet lamping to identify scheelite mineralisation. This lamping technique leverages scheelite’s natural fluorescence under UV light, enabling efficient detection of mineralised outcrops.
UV lamping successfully confirmed previously mapped Amsden Formation outcrops, refining geological interpretations. These Phase I reconnaissance efforts support both the Finley Basin project and broader regional tungsten exploration targets in western Montana, providing critical data to optimize the upcoming drilling program scheduled for late 2026.
Planned Phase I Drilling: 7,000 Metres Over 16 Holes
The 2026 drilling campaign will be IRIS’s first at Finley Basin, aiming to validate and expand historic tungsten mineralisation. The program includes up to 7,000 metres of diamond drilling across 16 locations, many on historical Union Carbide drill pads, allowing twin drilling for direct comparison and oriented drilling targeting mineralised zones based on updated geological models.
Drilling will utilize skid-mounted rigs adaptable for conventional and helicopter-supported access in challenging terrain. HQ-size core will be standard, with options for larger diameters as needed. Drill and helicopter contractors have been secured, enabling prompt commencement upon permit approval.
Permit Applications Submitted, Approval Expected Q3 2026
Permit applications were lodged with state and federal agencies in March 2026. Reviews are progressing, aiming for drilling to begin in August 2026 pending approvals. Early engagement and identification of previously disturbed sites have streamlined the environmental review process.
Permit finalisation is a key near-term catalyst, with IRIS targeting Q3 2026 for approvals, drilling mobilisation, and commencement. Initial drilling results are anticipated in Q4 2026.
Geological Context and Targeted Mineral Horizons
Situated in a premier North American mining jurisdiction, the Finley Basin Project targets scheelite mineralisation within the Amsden Formation and the tactite horizon at the Madison Formation base. Oriented drilling designs aim to intersect mineralised zones at optimal angles to maximize data quality and resource definition. The elevation range and terrain have informed equipment and contractor selection to ensure operational efficiency.
Expanding North American Critical Minerals Portfolio
Adding the Finley Basin Tungsten Project diversifies IRIS’s critical minerals portfolio beyond lithium, spreading exposure across multiple strategic commodities. This approach mitigates operational and market risks and positions IRIS to capitalize on distinct demand drivers for lithium and tungsten across various industries and geographies.
The timing aligns with heightened global emphasis on critical minerals supply chain security, especially within Western jurisdictions. IRIS’s dual presence in South Dakota lithium and Montana tungsten sectors offers investors diversified exposure to complementary geopolitical and macroeconomic trends.
Upcoming Catalysts and Exploration Timeline Through 2027
IRIS anticipates key milestones including drilling permit finalisation and Phase I drilling commencement in Q3 2026, with initial assay results expected in Q4 2026. The first half of 2027 will focus on geological model refinement integrating new drilling data with historical information to guide further exploration.
Additionally, IRIS is evaluating regional tungsten targets in western Montana, aiming to expand its portfolio leveraging Finley Basin’s established infrastructure. Investors should watch for updates on exploration results and regional activity as indicators of the company’s tungsten strategy progression.
Strategic Importance Amid Critical Mineral Demand and Supply Dynamics
Chairman Chris Evans highlights tungsten’s strategic role across defence, aerospace, energy, electronics, and advanced manufacturing sectors. Rising global demand and Western governments’ prioritization of critical minerals supply chain security underscore the significance of IRIS’s Montana tungsten exploration.
Positioned in a top-tier North American mining jurisdiction, IRIS’s Finley Basin Project aligns with geopolitical and macroeconomic trends favoring domestic critical minerals development. Successful resource definition could enhance North American tungsten supply resilience, appealing to investors focused on both mineral economics and critical supply chain considerations amid tightening global tungsten markets.
