Delta Lithium Ltd (ASX:DLI) has delivered a dual-project update that adds a potentially significant new commodity to its Yinnetharra project while Mt Ida continues to build resource confidence ahead of a scoping study.
The company's regional exploration campaign at Yinnetharra in Western Australia's Gascoyne region has returned eye-catching fluorite assays from surface sampling and a shallow drill program, while partner drilling at Mt Ida is consistently intercepting high-grade lithium at depth.
Fluorite grades rival best-in-class at Yinnetharra
Rockchip assays of Quartz Fluorine Veins from Yinnetharra returned grades of 86.09% CaF₂ from sample CAF0066, 85.89% CaF₂ from CAF0020, 75.61% CaF₂ from CAF0054 and 62.67% CaF₂ from CAF0015 — all comfortably above the 97% threshold that defines premium acid-grade fluorspar, suggesting the raw material quality is strong even before any processing.
Crucially, economic-grade fluorite has been identified across at least three distinct locations spanning more than 16 kilometres, pointing to a system of considerable regional scale rather than an isolated vein occurrence. Historical work completed by Parkmin in 2001 has been confirmed and extended by Delta's follow-up sampling.
A brief, opportunistic drill program totalling 876 metres — conducted while the rig was mobilising back to East Malinda — has confirmed the mineralisation extends at depth. Notable intercepts include 8 metres at 18% CaF₂ from 15 metres in CGEX002, 2 metres at 23% CaF₂ from 34 metres in CGEX007, 7 metres at 16.4% CaF₂ from 48 metres in CGEX006, and a broad 52-metre intersection averaging 2.28% CaF₂ from surface in CGEX013.
The results confirm both vein-hosted and broader granite/greisen-hosted fluorite mineralisation styles, and the geochemical dataset shows correlation with pathfinder elements lead and bismuth — giving the team a vectoring tool to apply systematically across the wider 2,300 square kilometre tenure.
Plan View to Yinnetharra MRE’s, New Mining Lease over East Malinda and Li surface anomalism across Project
A market worth watching
The fluorite discovery is well-timed. Fluorspar is classified as a critical mineral by the United States, the EU, Japan, India and other major economies, with global supply heavily concentrated in China — a dynamic that has sharpened interest in new sources from stable jurisdictions like Western Australia.
The market splits between acid-grade material (greater than 97% CaF₂), which commands premium pricing for use in chemical, battery and semiconductor applications, and lower-value metallurgical grades. Pricing has held between US$450 and US$600 per tonne in recent years, supported by tightening supply and growing downstream fluorochemical demand — including fluorine-based lithium battery electrolytes, which align directly with Delta's existing critical minerals focus.
Managing Director James Croser described the fluorspar results as "exciting" and noted that opportunistic drilling during the recent program had "yielded very high-grade results worthy of future follow up."
“The geology team at Yinnetharra continues to deliver a solid greenfields performance, with exciting fluorspar assays coming from the ongoing fieldwork campaign. Opportunistic drilling of these surface expressions during the recent program has yielded very high-grade results worthy of future follow up. Additionally, an adjacent mining lease application to the current Malinda application has been submitted, to allow for potential underground extensions to mining as the Malinda pegmatites plunge to the east at depth.
Mt Ida lithium: resource confidence building ahead of scoping study
At Mt Ida, located around 240 kilometres north of Kalgoorlie, drilling by Ballard Mining (ASX: BM1) continues to return high-grade lithium intercepts that are feeding directly into Delta's resource model at minimal cost to the company.
Recent significant intercepts include 11.9 metres at 1.36% Li₂O from 423 metres in BDG001, 6 metres at 1.19% Li₂O from 170 metres in NEB047, 7.4 metres at 1.36% Li₂O from 219 metres in DFS674A, and 5 metres at 1.71% Li₂O from 332 metres in DFS619.
The BDG001 result is particularly notable — it intercepted a footwall pegmatite approximately 100 metres below the Sister Sam deposit, sitting on the fringe of the current model and pointing to meaningful down-dip extension potential.
On the metallurgical side, downstream processing of a Mt Ida mica concentrate has successfully produced 99.8% lithium carbonate (Li₂CO₃) — a battery-grade result that de-risks the processing pathway. Further testwork is underway to optimise and refine the flowsheet, including work on tantalum and rubidium byproducts.
Mt Ida currently holds a total resource of 14.8 million tonnes at 1.2% Li₂O, 170ppm Ta₂O₅ and 0.42% Rb₂O across the Sister Sam and Timoni deposits, within an already-permitted project area carrying granted mining leases.
"At Mt Ida, further lithium results continue to increase the drill density in the upper portions of Sister Sam and Timoni, which will provide valuable certainty to a scoping study to be commenced this quarter. The additional diamond core from these holes is particularly useful as the company explores various metallurgy workflows with regard to tantalum and rubidium byproducts,” Croser said.
Scoping study to commence this quarter
The company has confirmed that a scoping study for Mt Ida will begin during the current quarter. The infill drilling program targeting the upper portions of Sister Sam and Timoni is designed to provide the geological confidence needed to support that study, with Croser noting the additional diamond core is also proving useful for metallurgical flowsheet development covering tantalum and rubidium co-products.
What's next
At Yinnetharra, the company is awaiting final RC drill results from more than 1,200 samples still in the lab, with results from the high-priority East Calypso target — proximal to the same source granite as the Malinda lithium system — expected imminently. A first-pass fluorite targeting assessment across the broader tenure is also planned, drawing on lead and bismuth anomalism in the existing database.
An additional mining lease application (M09/0186) has been submitted to cover underground mining potential of the Malinda pegmatites as they plunge east at depth, complementing the existing M09/185 application.
At Mt Ida, recent drill results will be incorporated into an updated resource model, with further mica concentrate testwork and the commencement of the scoping study the key near-term milestones.
Delta's balance sheet remains healthy, with a cash position of $52.2 million as of March 31, 2025, and approximately $120 million in ASX-listed investments based on 8 May 2026 closing prices.