Delta Lithium Reports 21.9Mt Lithium Resource at Yinnetharra, 14.6Mt at Mt Ida

Exploration Momentum Builds at Yinnetharra

Delta Lithium Limited (ASX, DLI) has kicked off a significant drilling campaign at its 100% owned Yinnetharra Lithium Project in Western Australia's Gascoyne Lithium Province. Covering more than 3,100 square kilometres, Yinnetharra boasts a current mineral resource estimate (MRE) of 21.9 million tonnes at 1.0% lithium oxide (Li2O). The company has identified six high-priority regional targets through detailed ground mapping and geochemical sampling conducted throughout 2025, including prospects on newly acquired tenure.

With heritage surveys completed and earthworks largely prepared, the first phase of reverse circulation (RC) drilling is focusing on extending the high-grade Jameson Prospect, which currently holds an MRE of 0.8Mt at 1.66% Li2O. Complementing this, a high-resolution drone magnetic survey has refined drill targets, enabling a systematic approach to exploration along the 20-kilometre prospective Leake Springs metasediment unit.

Mt Ida, Unlocking New Lithium and Rubidium Potential

Meanwhile, at the Mt Ida Project, an advanced lithium and tantalum asset with a 14.6Mt resource at 1.2% Li2O, Delta is capitalising on recent gold-focused drilling by Ballard Mining (ASX, BM1). This drilling has serendipitously intercepted significant lithium intervals, including a standout 37 metres at 2.05% Li2O from 217 metres depth at the Sister Sam prospect. Notably, a new lithium-caesium-tantalum (LCT) pegmatite was discovered in the footwall of Sister Sam, underscoring the project's exploration upside.

Adding a compelling dimension to Mt Ida’s value proposition, Delta has identified high-grade rubidium mineralisation closely correlated with lithium and tantalum zones within the existing resource framework. Rubidium, a critical mineral with growing demand in emerging technologies, is poised to be incorporated as a co-product in the upcoming MRE update scheduled for the December quarter. This strategic move could enhance the economic viability of Mt Ida’s development pathway.

Strong Financial Position Supports Growth

Delta Lithium enters this phase of exploration and development with a robust financial footing. As of 30 September 2025, the company holds $56.8 million in cash alongside approximately $100 million in ASX-listed investments, including significant stakes in Ballard Mining and other entities. This strong balance sheet underpins Delta’s capacity to advance drilling programs, project approvals, and feasibility studies without immediate capital constraints.

Managing Director James Croser emphasised the strategic timing of the drilling campaigns, noting that each additional resource tonne discovered at Yinnetharra enhances the prospects for a positive final investment decision (FID) once lithium prices reach economically meaningful levels. He also highlighted the exciting potential at Mt Ida, where the convergence of lithium, tantalum, and rubidium resources could unlock multiple revenue streams.

Looking Ahead, Drilling and Development Milestones

Delta plans to complete the initial priority regional drilling at Yinnetharra, followed by subsequent phases contingent on results. Concurrently, the company is progressing mining lease applications and environmental permitting, with no new risks identified in recent surveys. Water exploration programs are also advancing to secure critical resources for future mining operations.

At Mt Ida, the forthcoming MRE update incorporating rubidium data will be a key milestone, alongside further metallurgical investigations to optimise co-product recovery. These developments, combined with the spin-out of gold assets into Ballard Mining earlier this year, position Delta Lithium to focus squarely on maximising the value of its lithium portfolio.