Dover Castle Project

 

Overview

The historic Dover Castle tin mine and operations in its periphery were exploited for their rich tin, silver, lead and zinc deposits beginning in the late 1800s, and made a significant contribution to the economic development of the local community and region.

Given the potential scale of the company’s flagship project, Dover Castle, the discovery of significant quantities of critical minerals, and the global focus on transitioning to a low-carbon economy, Dover Castle Metals has the potential to not only reignite the local community and region, but also Queensland and Australia’s economies.

This was affirmed in the recently completed Dover Castle Project Scoping Study. The study was prepared by leading industry experts, Ausenco, together with independent specialists Measured Group, Optimal Mining, Rock Financial and Natural Resource Assessments, and the DCM team.

It is noted that many of critical studies are at a PFS standard, including deposit definition, mining and economic evaluation, providing a robust assessment of the project.

Mineralisation

The Project is underpinned by a structurally complex, multi-phase epithermal to intrusion related mineral system. The Project sits within a fertile segment of the Tasman Orogenic Belt, where intersecting volcanic calderas and intrusive events have given rise to a highly prospective geological environment. Host rocks include quartz-eye porphyritic ignimbrites, rhyolitic flows, and intermediate intrusions, representing a long-lived, evolving hydrothermal system capable of sustained metal precipitation and zoning.

Mineralisation at Dover Castle is silver-dominant and polymetallic in nature, comprising significant endowments of silver (Ag), lead (Pb), zinc (Zn), tin (Sn), and indium (In). The August 2025 Mineral Resource Estimate (MRE) (see section below) confirms a large-scale system with 72 million tonnes at 29 g/t Ag, 0.8% Pb, 0.7% Zn, 0.07% Sn and 9 g/t In, making it one of the most compelling undeveloped silver-rich polymetallic deposits in Australia. Silver represents the primary value contributor, with associated base and technology metals offering multi-commodity exposure in key global supply chains.

The system exhibits clear vertical and lateral metal zonation, ranging from Ag-Pb-Zn at upper levels to Sn-In enrichment at depth, consistent with hybrid low-sulphidation epithermal overprinting a deeper porphyry-related source. ALS Canada has confirmed indium grades exceeding 5,000 ppm, placing Dover Castle among the highest known indium-enriched systems globally

The combination of high-value critical and strategic metals, coherent mineralised architecture, and untested lateral and vertical extensions support a compelling case for ongoing resource growth. Dover Castle is now positioned not merely as a single deposit, but as the potential anchor of a district-scale polymetallic system with meaningful exploration upside and long-term development optionality.

Outstanding Findings from the Dover Castle Project Scoping Study

The Scoping Study was prepared by leading industry experts, Ausenco, together with independent specialists Measured Group, Optimal Mining, Rock Financial and Natural Resource Assessments, and the DCM team. The study is technically strong and highly defendable.

The Dover Castle Project (Project) represents a rare opportunity to develop a high-margin, low-capex silver/ tin led polymetallic asset in a secure, infrastructure-rich jurisdiction.

The Project is underpinned by a robust JORC 2012-compliant Mineral Resource Estimate (MRE) and supported by a technically simple and scalable development strategy.

The August 2025 MRE, shown below, contains 72 million tonnes at 70 g/t silver equivalent (AgEq). The resource has been reported above a 20 g/t AgEq cut-off, reflecting pit optimisation, metal recoveries, and long-term price assumptions.

The near surface resource allows for cost effective open-cut mining with conventional gravity processing supported by XRT Ore Sorting and flotation to recover high-value tin, silver, lead, zinc, and indium concentrates. Processing has been validated through multiple phases of metallurgical test work and supported by a comprehensive scoping-level design. Concentration production across the Base Case life of mine is shown below.

The Scoping Study hasn’t identified any major potential ‘show-stoppers’. Further, significant mine elements have been designed to support the Project’s regulatory approvability and reduce closure liabilities. This includes infrastructure sited to avoid sensitive ecological communities and dry-stack tailings eliminating the need for a dedicated Tailings Storage Facility. The site layout is shown below.

The current ‘Base Case’ Project utilises only a portion of the total resource estimate and focuses exclusively on higher-confidence domains of the Indicated Resource. A future relatively small and targeted drilling program designed within the Base Case pit shell, has the potential to convert approximately 47% of the Inferred Resource to an Indicated Resource and would provide significant short term upside potential. This scenario is referred to as the ‘Mid-Case’. Our team has a strong record of converting Inferred Resource to Indicated Resource through targeted drill programs (a snapshot of the strong economics from financial modelling is provided in the About page).

Significant mineralisation remains outside the Base Case pit shell, with the MRE representing only a fraction of the known mineralised system at the Dover Castle Project (which remains open in all directions) in addition to our other feeder projects such Tommy Burns, Koorboora, Lady Jane and Station Hill.

These deposits position DCM to transition from a single-project developer to a regional critical minerals operator.

VRIFY-driven 3D visualisation (example shown below), LiDAR modelling, and digital geology frameworks are rapidly accelerating the de-risking of these assets.