Dart Mining Unveils Deep Walwa Tin Targets Ahead of October Drilling

Extensive Historical Data Unlocked at Walwa

Dart Mining NL (ASX:DTM) has completed a comprehensive compilation and verification of 150 historic drill holes totalling 7,672 metres across its Walwa Tin Project in Northeast Victoria. This digital database integrates reverse circulation, percussion, and diamond drilling records dating back to the 1960s and early 1980s, providing the company with a robust foundation to refine exploration targets within a 3km by 1km mineralised corridor.

The meticulous reconciliation of drill collars, lithology logs, and assay intervals against original Geological Survey of Victoria reports has corrected previous data errors and standardised geological codes. Despite limitations such as the absence of downhole surveys and QAQC records in the historic data, Dart Mining’s efforts have significantly enhanced the geological understanding of the Walwa tin field.

Two High-Priority Targets Emerge from Data Review

Analysis of the compiled data has revealed two prime drilling targets beneath the historic Walwa (Mt Alwa) tin mine. The first is a potential large-tonnage, high-grade greisen-hosted tin mineralisation zone situated 400 to 600 metres below surface, interpreted as the apex of a late-stage felsic intrusion. The second target involves repeated mineralised aplite-pegmatite dykes at depth, with seismic reflection surveys indicating at least four additional dykes thicker than 4 metres beneath those previously drilled.

These sub-horizontal dykes, ranging from 5 to 18 metres thick at surface, form a stacked dome-like structure with significant tin and tantalum mineralisation historically documented. Dart Mining’s Chairman James Chirnside highlighted the excitement surrounding these targets, noting that the planned diamond drilling commencing in October 2026 aims to test these substantial and potentially higher-grade zones.

Historical Estimates Indicate Significant Resource Potential

While not compliant with modern JORC standards, pre-2012 historical estimates by Union Corporation reported approximately 8.64 million tonnes at 0.163% tin (Sn) and 50 ppm tantalum pentoxide (Ta2O5) at Walwa. A higher-grade selective zone of nearly 1 million tonnes at 0.38% Sn was also delineated. These figures, alongside documented historic production of 162 tonnes of tin including 97,000 tonnes processed in the 1970s, underscore the project's significance.

Union Corporation’s own assessments suggested percussion drilling likely underestimated grades compared to diamond core, indicating potential upside in grade with modern drilling techniques. Dart Mining cautions that these historical estimates require confirmation through contemporary exploration and resource modelling.

Geological Context Supports Exploration Strategy

The Walwa tin mineralisation is genetically linked to the Silurian Koetong Granite, part of the Wagga Tin Belt within the Lachlan Fold Belt. Tin-bearing pegmatites, aplites, and greisen dykes emanate from this granite, with late-stage magmatic-hydrothermal processes concentrating tin as cassiterite in peripheral fractures. Greisen zones, known globally for hosting world-class tin deposits, represent an enticing exploration target beneath Walwa.

The mineralised dykes form a dome-like structure with dip angles varying from 20 to 30 degrees, and seismic surveys have confirmed the presence of thick, mineralised dykes at depth. The Bounce and Mt Alwa South prospects within the project area also show promising mineralisation styles and historic drill intercepts that support further exploration.

Next Steps and Exploration Outlook

Dart Mining plans to initiate diamond drilling in October 2026, focusing on deep targets including the greisen zone atop the causative intrusion and the stacked aplite-pegmatite dykes. The program will incorporate downhole surveying and rigorous QAQC protocols to validate historic data and refine resource estimates. Additional work will include DGPS verification of drill collars and potential twin drilling to benchmark historical results.

This drilling campaign represents a critical step in unlocking the Walwa tin system’s deeper potential, with the possibility of uncovering higher-grade mineralisation zones that could materially enhance the project’s value.