Dart Mining NL (ASX:DTM) reported further exploration results from its Walwa Tin Project in Northeast Victoria, highlighting assay outcomes from rock chip samples collected during a June 2026 field program. The update focused on tin, tantalum, niobium and other associated elements identified within the historic Walwa (Mt Alwa) tin mine area.

The company released the exploration update on 16 September 2026, reporting results from four rock chip samples collected from the historic Walwa tin mine and Mt Alwa South prospect. The results included elevated tin grades along with associated tantalum, niobium, lithium, rubidium and caesium values.

The exploration results form part of Dart Mining’s broader assessment of the Walwa tin-tungsten project, where the company is evaluating historical mining areas, geological information and potential drill targets. The company stated that diamond drilling at Walwa was planned to commence in October 2026, with preparations underway across proposed drill sites.

Company Overview

Dart Mining NL (ASX:DTM) is an Australian mineral exploration company focused on gold, tin, tungsten, antimony and other critical mineral opportunities.

The company holds exploration interests across Victoria and Queensland, including the Walwa Tin Project in Northeast Victoria. Dart Mining’s exploration strategy includes evaluating historical mining areas, reviewing existing geological data and advancing selected projects through exploration programs.

At Walwa, Dart Mining holds 100% owned granted tenements covering the Walwa, Cudgewa and Berringama areas. The Walwa tenement, EL007426, covers approximately 499 square kilometres.

The Walwa area has historical tin production activity, with the Mt Alwa tin mine representing one of Victoria’s historic primary tin production areas. The company noted that approximately 97,000 tonnes of ore were processed during the final mining period in the late 1960s.

Details of the Walwa Exploration Update

Dart Mining’s 16 September 2026 update provided assay results from four rock chip samples collected during June 2026. Three samples were collected from the historic Walwa open pit, while one sample came from the Mt Alwa South prospect located approximately 700 metres south of the pit.

The highest-grade result came from sample WWP002, an in-situ grab sample collected from the southwest wall of the historic Walwa open pit. The sample returned 3.96% tin, along with 165 parts per million tantalum and 197 parts per million niobium.

Other sample results included:

  • WWP001 returned 1.09% tin from a float boulder of greisenous pegmatite located on the pit floor.
  • WWP003 returned 0.61% tin from material north of the pit.
  • WAS001 returned 0.40% tin from an outcrop grab sample at Mt Alwa South.

The company reported that all four samples contained elevated lithium, rubidium and caesium levels, which are associated with fractionated tin-tantalum pegmatite systems.

The company stated that the highest-grade sample, WWP002, contained coarse cassiterite within pegmatite material from the southwest wall of the historic pit. Other samples represented greisenous pegmatite and float material associated with the historical mining area.

Dart Mining noted that the samples were selective grab samples collected from visibly mineralised rock and were not representative of the average grade of the wider dyke systems. However, the results confirmed the presence of cassiterite-bearing mineralisation within the pegmatitic and greisenised phases of the dykes.

Historical Exploration Data and Geological Context

The Walwa tin area has been explored by several previous operators, with historical sampling programs providing additional geological information for Dart Mining’s current assessment.

Historical sampling identified tin and tantalum occurrences across several areas, including Walwa, Mt Alwa South, Snake Gully and surrounding prospects. Previous results included tin-bearing samples and tantalum enrichment in parts of the broader exploration area.

The company’s review of historical information identified a pattern where tin grades were higher within greisenised and pegmatitic phases near the Walwa pit, while tantalum and niobium enrichment extended into surrounding areas such as Mt Alwa South, Redbank Creek and Snake Gully.

The Walwa geological setting includes tin-bearing greisenous aplite-pegmatite dykes that have been worked historically. These dykes occur within metasedimentary rocks and include aplite, pegmatite and greisen phases containing cassiterite and related minerals.

The company’s geological interpretation suggests that the Walwa tin system may be associated with a buried granite source beneath the historic mining area. This interpretation is being evaluated through planned exploration activities.

Planned Exploration Activities

Following the sampling results, Dart Mining outlined further exploration activities at Walwa.

The company planned to complete approvals for access and commence diamond drilling targeting deeper tin-mineralised dykes and potential tin-bearing greisen zones.

Additional work programs include systematic rock chip and channel sampling of tantalum-enriched albitite dykes at Snake Gully, along with field inspections and sampling at other prospects including McHargs tungsten and Hall’s gold areas.

The planned drilling program is intended to test geological interpretations and assess mineralisation continuity at depth.

Industry Context

Tin and tantalum are considered important minerals used across industrial applications, including electronics, technology Manufacturing and specialised materials.

Exploration companies evaluating tin-tantalum systems typically focus on geological continuity, grade distribution, mineral characteristics and potential development pathways.

The Walwa project combines historical mining activity with modern exploration techniques, including geological mapping, sampling programs and planned drilling. Dart Mining’s current work is focused on improving understanding of the mineralised system and identifying areas requiring further assessment.

Risk and Uncertainties

Dart Mining’s exploration activities remain subject to risks associated with mineral exploration, including geological uncertainty, exploration success, funding requirements, regulatory approvals and future development decisions.

The reported rock chip results are selective samples collected from visibly mineralised material and are not representative of average grades across the broader dyke systems. Further exploration work, including drilling, will be required to assess the scale and continuity of mineralisation.

The company also noted that historical exploration results require careful interpretation, as previous sampling programs were conducted using different methods and reporting standards.

Future project outcomes will depend on exploration results, technical studies, approvals and the company’s ability to progress development activities.

Future Outlook

Dart Mining’s immediate focus at Walwa is advancing exploration activities through drilling, additional sampling and geological evaluation.

The company plans to test deeper targets beneath the historic workings and assess the potential continuation of tin-bearing structures. Further work across Snake Gully, McHargs and Hall’s prospects is also planned as part of the broader exploration strategy.

The Walwa project remains an important component of Dart Mining’s Northeast Victoria exploration portfolio, with ongoing activities aimed at improving geological understanding and defining future exploration targets.