Diatreme Resources Boosts Si2 Silica Sand Resource by 10.6 Percent

Significant Resource Expansion at Si2 Deposit

Diatreme Resources Limited (ASX:DRX) has announced a 10.6% upgrade to the Mineral Resource Estimate (MRE) for its Si2 Deposit within the Northern Silica Project in North Queensland. The resource base has grown from 272.5 million tonnes to 301.5 million tonnes of high-purity silica sand, with 62% now classified as Measured, reflecting increased geological confidence. Notably, the updated MRE reveals mineralisation extending further to the south-east, enlarging the deposit footprint and enhancing future exploration potential.

This expansion is a meaningful development for Diatreme’s ambitions to supply critical minerals for photovoltaic glass, a key component in solar panel manufacturing. The Si2 Deposit sits in the Cape Bedford - Cape Flattery Dune Field, adjacent to the Port of Cape Flattery, positioning it well for efficient logistics to global markets.

Innovative Grade Modelling Incorporates Colour Data

Beyond tonnage growth, Diatreme has integrated colour attributes into the underlying grade model alongside traditional geochemical data. This novel approach, derived from systematic drilling and logging, is expected to enhance stage-wise predictive processing studies and optimise mine scheduling and product blending. Such granularity aims to tailor product specifications to exacting customer requirements, potentially de-risking the initial mine plan.

The updated grade model forms the geological foundation for the company’s Pre-Feasibility Study (PFS), which is in its final drafting phase. This study will refine mine design and scheduling, incorporating the expanded resource and new data inputs.

Metallurgical Testwork and Offtake Engagements Next

Diatreme plans a metallurgical testwork program focusing on small-increment variability samples to validate whether colour can predict processing behaviour. If successful, this will directly inform processing flowsheet selection and product consistency planning, key to maintaining quality for photovoltaic and industrial glass applications.

Concurrent metallurgical work will refine final product specifications and support ongoing discussions with prospective customers, moving toward binding offtake agreements in the global silica sand market.

Casuarina Deposit Development Continues

Alongside Si2, Diatreme is advancing technical work at the Casuarina deposit, including drilling, sampling, and geological logging. This aims to build the dataset required for a future Mineral Resource Estimate compliant with the JORC Code (2012 Edition). The Casuarina deposit remains at an earlier stage of development but is integral to Diatreme’s broader silica sand portfolio.

This resource upgrade follows recent strategic moves by Diatreme, including asset sales and joint venture consolidations, which have strengthened the company’s financial position and streamlined its silica sands operations, as detailed in the company’s April and March announcements. These actions have set the stage for the current resource growth and ongoing project advancement Northern Silica Project drilling supports resource upgrades and Diatreme Resources Advances Silica and Zircon Projects Amid Strategic Asset Sale.

Robust Geological and Sampling Framework Underpins Confidence

The MRE is supported by an extensive drilling database of 529 vertical holes, employing vacuum, aircore, and hand auger methods. The geological model leverages high-resolution LIDAR topography and accounts for dune morphology and groundwater levels to precisely define resource boundaries. Bulk density determinations and multiple estimation techniques, including Inverse Distance Weighting and Ordinary Kriging, have validated the robustness of the resource figures.

The deposit’s homogeneous silica sand mineralisation, combined with rigorous QA/QC protocols and metallurgical testwork, supports the classification into Measured, Indicated, and Inferred categories with high confidence. The inclusion of colour data is a distinctive enhancement that could provide a competitive edge in processing optimisation.

Environmental and Community Considerations in Progress

Diatreme is progressing an Environmental Impact Statement (EIS) for the Northern Silica Project, acknowledging the proximity of sensitive wetlands and protected species. Early assessments suggest manageable environmental impacts consistent with open-pit mining and conventional processing methods. The company emphasises its commitment to ESG principles, working closely with local communities and stakeholders to ensure sustainable operations.