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.

The geological setting of the Dover Castle Project is intricate, and characterised by a diverse range of rock types, including volcanic welded ignimbrites, rhyolitic lavas, pyroclastics, and intrusive rhyolitic volcanics. The geological structures and alteration minerals in the area include intense silicification, sericitisation, and phyllic alteration.

Mineralisation

The Project exhibits a variety of mineralisation styles, each with its unique characteristics. These include massive, disseminated, vein, breccia, interstitial, and overprinting polymetallic ores. The Project is particularly notable for its polymetallic epithermal lode type deposits, which are associated with linear, steeply dipping fault systems containing metals such as zinc, lead, silver, tin, indium, copper and others in a variety of mineral species and concentrations. The alteration enveloping the veins, characterised by intense silicification and sericitisation, indicates a low-sulphidation epithermal style system rather than a porphyry style, as previously postulated.

The mineralised veins and faults typically exhibit a steep eastward dip, aligning with the prevailing structural trends of the region, characterised by north-south or north-northeast orientations—a critical feature for geological interpretation and exploration in the Dover Castle area.

The alteration and metal associations are zoned on a metre to ore-field scale. Around individual or clustered ore lodes, proximal alteration is dominated by sulfidation and intense phyllic and/or argillic alteration at scales ranging from 0.1 to 10m. The ores exhibit zoning from Sb-As-Ag-rich in the north to Zn-Pb-Sn rich in the middle, and Cu-Zn rich in the south, indicating a progressive increase in ore precipitation temperatures to the south — a zonation also observed vertically. Exceptional enrichments include > 500 ppm Ag, 6,000 ppm Sb, and > 5% Sn, all associated with rocks dominated by massive galena, sphalerite, and local arsenopyrite. The current mineralisation envelope is displayed below.

Exploration and value capture

The Dover Castle Project 2023 Inferred Mineral Resource Estimate (MRE), prepared by Measured Group, an international, industry leading, technical resource consultancy firm, was based on previous MREs and yielded outstanding results. Rigorous data management, geostatistical analysis, and block modelling have been employed to estimate Inferred Mineral Resources.

The MRE consolidated assays from a total of 172 boreholes, including 161 reverse circulation (RC) holes and 11 diamond drill holes (DDH). The combined length of these boreholes, shown on the figure below, was ~27,862m with an average of 162m per hole. The majority of the drilling has been completed by the Company, primarily since August 2022.

A summary of the inferred Mineral Resource Estimate is shown below.

A plan view and sectional view looking south-east of the block model displaying Ag EQ are displayed below.

The shallow surface deposit indicates that it is amenable to open pit mining, and preliminary pit optimisation and economic studies are highly encouraging.

The deposit remains open in all directions and at depth; there is significant potential to increase the total MRE through additional targeted drilling, which commenced in December 2023.

The exploration program was underpinned around Measured Group’s data driven resource model, with real-time feedback proving invaluable throughout the process.

Dover Castle Metals is excited to expand and upgrade the project based on our current program of works, while also evolving our metallurgical and economic studies, which will boost confidence in the Dover Castle Project.