Mt Ida Resource Grows to 14.8 Mt with 0.42% Rubidium Oxide

Strategic Resource Update

Delta Lithium Limited (ASX – DLI) has released a significant update to its Mt Ida Lithium Project Mineral Resource Estimate (MRE), now totalling 14.8 million tonnes grading 1.21% lithium oxide (Li2O), 0.42% rubidium oxide (Rb2O), and 170 parts per million tantalum pentoxide (Ta2O5). This update notably includes the delineation of one of the highest-grade rubidium oxide resources globally, positioning Mt Ida as a critical supplier of this increasingly strategic metal.

The inclusion of rubidium, a specialty metal with growing demand in quantum technologies, defence, and biomedical applications, adds a valuable co-product revenue stream to the project. Rubidium’s critical mineral status in key markets such as the United States, Japan, and Europe further underscores its strategic importance amid global supply chain realignments.

Robust Metallurgical Foundations

Metallurgical testwork confirms that the existing whole ore flotation (WOF) flowsheet effectively recovers rubidium during the mica pre-float stage, achieving average recoveries of approximately 90%. This process also recovers a significant portion of lithium, producing a high-grade lithium-rubidium concentrate. Ongoing downstream processing studies, led by Strategic Metallurgy, are exploring optimization pathways to produce high-purity lithium carbonate and rubidium carbonate, with promising initial leaching and impurity removal results.

These metallurgical advances suggest that rubidium can be extracted with minimal changes to the current processing flowsheet, potentially enhancing project economics without substantial capital expenditure increases.

Permitting and Exploration Synergies

The Mt Ida Project is fully permitted for both open pit and underground mining, a significant advantage that reduces development risk and accelerates potential production timelines. The project benefits from ongoing gold drilling by Ballard Mining (ASX – BM1), which is providing incremental lithium and rubidium assay data through pegmatite intercepts. This synergy is improving resource confidence and classification, with 7.7 million tonnes now classified as Measured and Indicated at elevated grades.

Delta Lithium’s strong cash position, approximately $55 million, alongside $108 million in listed investments, supports continued exploration and development activities, including at its Yinnetharra Lithium Project.

Market Context and Outlook

Rubidium’s market remains relatively small but is expanding rapidly due to its unique properties and applications in next-generation technologies such as quantum sensors and atomic clocks. The current market is dominated by Chinese producers, making Delta’s Western Australian resource strategically valuable to countries seeking supply chain diversification.

At current rubidium carbonate prices of around USD 1,067 per kilogram, the rubidium component could significantly enhance Mt Ida’s project value. However, the market’s opacity and geopolitical factors introduce some uncertainty, which Delta aims to address through ongoing processing studies and market engagement.