PC Gold’s re-assay program using advanced Photon Assay technology has confirmed a significant 55.5% uplift in gold grades at its Spring Hill project, challenging historical estimates and setting the stage for a resource upgrade.
- 939 historic drill core samples re-assayed with Photon Assay
- Weighted average gold grade uplift of 55.5% over key intervals
- Re-assay covers over 10% of drilling database and 25% of Hong Kong domain samples
- Photon Assay results validate under-reporting by conventional Fire Assay
- Full Mineral Resource Estimate re-modelling underway incorporating new data
Context and Significance
PC Gold Limited (ASX, PC2) has announced a breakthrough in its assessment of the Spring Hill Gold Project in the Northern Territory. A comprehensive re-assay program using Chrysos Photon Assay technology on 939 historic diamond drill core samples has revealed a striking 55.5% increase in the weighted average gold grades compared to previous Fire Assay results. This finding not only challenges the historical resource assumptions but also highlights the limitations of conventional assay methods in capturing the true gold content of the deposit.
Technical Insights and Methodology
The samples re-assayed represent over 10% of the entire drilling database and more than 25% of the samples within the Hong Kong mineralised domains, which account for 83% of the current Mineral Resource Estimate (MRE) ounces. The Photon Assay method, which uses high-energy X-ray fluorescence, is particularly adept at detecting coarse and free gold particles that often cause under-reporting in traditional Fire Assays due to the nugget effect.
PC Gold’s approach involved re-assaying the other half of the mineralised drill core stored on site, allowing a direct like-for-like comparison. The results consistently showed higher grades across most intervals, especially in the critical 0.5 to 2.5 grams per tonne (g/t) gold range, which is vital for economic viability.
Implications for Resource and Project Development
The uplift is particularly pronounced in the low-grade halo material surrounding the higher-grade core of the Hong Kong zone, with increases of up to 76% in samples below the 0.5 g/t cut-off grade. This halo defines the scale of the deposit and suggests potential for meaningful increases in both tonnage and contained ounces when incorporated into the MRE.
PC Gold is now undertaking a full re-modelling of the Spring Hill MRE, originally completed by CUBE in 2024, to integrate these Photon Assay results alongside 936 historical Screen Fire Assays and 27 recent resource definition drill holes. This updated modelling aims to reassess the tonnes, grade, and overall contained gold ounces, potentially enhancing the project’s economic profile.
Historical Context and Validation
The discovery of under-reporting aligns with previous metallurgical test programs and a bulk mining trial conducted in 2017, which demonstrated that gold production exceeded predictions based on conventional assays by over 45%. These new results independently confirm that earlier PC Gold test work consistently returned higher grades, reinforcing confidence in the Photon Assay method as the preferred analytical technique moving forward.
Looking Ahead
With environmental approvals in place and a strong balance sheet, PC Gold is well-positioned to advance Spring Hill through feasibility and towards production. The company’s dual strategy of infill drilling to upgrade resource confidence and aggressive exploration to expand the resource base remains on track. The recent discovery of the Macau extension zone and ongoing exploration at the Lasagne Target and Eastern zones could further add to the resource inventory, pending assay results.
Bottom Line?
PC Gold’s Photon Assay breakthrough could redefine Spring Hill’s resource potential, but the market awaits the updated Mineral Resource Estimate and feasibility outcomes.
Questions in the middle?
- How much will the updated Mineral Resource Estimate increase contained gold ounces?
- What impact will the grade uplift have on project economics and mine planning?
- Will exploration of Macau and other targets deliver further resource growth?