Granite Castle Resource Update: 620Kt at 3.22g/t Gold and 62g/t Silver Confirmed

Resource Update and Strategic Context

Native Mineral Resources Holdings Limited (ASX, NMR) has delivered a significant update to its Granite Castle gold-silver project in Queensland, reporting a Mineral Resource Estimate (MRE) of 620,000 tonnes grading 3.22 grams per tonne gold and 62 grams per tonne silver. This equates to 64,500 ounces of gold and 1.24 million ounces of silver, classified under the JORC 2012 Code as Indicated and Inferred resources. The update, prepared by H&S Consultants Pty Ltd, reflects a more conservative pit floor depth of 560 meters above sea level, resulting in a 26% reduction in tonnage but a 10% increase in gold grade compared to the 2008 estimate.

Geological and Operational Insights

The Granite Castle deposit is characterised by steeply dipping shear zones hosting gold and silver mineralisation, with two main lodes identified, the Main Lode and the East Lode. Historical drilling data from 1988 to 2007, comprising mostly reverse circulation drilling supplemented by diamond core, underpins the resource estimate. The deposit extends approximately 600 meters along strike and to depths of up to 140 meters below surface within the current resource boundary, with mineralisation remaining open at depth and along strike.

Importantly, Granite Castle lies within trucking distance of NMR’s recently commissioned Blackjack operations, offering potential synergies in ore processing and operational efficiencies. The company envisions a straightforward open pit mining operation with ore either processed onsite or trucked to Blackjack, enhancing the project's economic viability.

Next Steps and Development Plans

With the updated MRE now compliant with modern reporting standards, NMR is poised to fast-track Granite Castle towards mine readiness. Planned activities include detailed fieldwork to reassess historical mapping and sampling, resampling of historic diamond core, and a drilling campaign anticipated to commence later this year. Metallurgical testwork, drawing on previous studies indicating potential for flotation and cyanide leach processing, will be expanded to better define recovery parameters.

These efforts aim to underpin a scoping study that will evaluate the project's development potential, including mining methods and environmental considerations. The company is also assessing acid mine drainage mitigation strategies, leveraging local calcareous materials to manage environmental impacts responsibly.

Challenges and Considerations

While the resource update marks a critical milestone, it relies heavily on historical drilling data with some limitations in quality assurance and quality control documentation. NMR acknowledges the need for twin diamond drilling to validate historical reverse circulation results and improve confidence in the resource classification. Additionally, metallurgical testwork remains preliminary, necessitating further investigation to optimize processing routes.

Environmental and permitting aspects are in early stages, with the company committed to responsible waste management and compliance with mining license conditions. The project's sub-tropical climate and wooded eucalypt vegetation present manageable but important factors for operational planning.