Cobra Resources plc (LSE: COBR), which is developing the Wudinna ionic rare earth project and the Manna Hill copper project in South Australia, has published updated diagnostic leach results from 42 drill return samples tested at the Australian Nuclear Science and Technology Organisation. The results, which represent a reissue of an earlier announcement correcting the inclusion of internal completion notes, confirm recoveries of up to 88.4% total rare earth plus yttrium from Pidinga formation samples at the Boland discovery area. Managing Director Rupert Verco stated that the programme aids in identifying both opportunities and variability that must be reflected in the upcoming scoping study, as the company pursues a strategy of building an efficient, scalable in situ recovery operation.

Key Points

  • Cobra Resources plc (LSE: COBR) is an LSE-listed critical minerals developer focused on South Australia
  • Diagnostic leach testing of 42 samples from the Boland and Head discovery areas returned rare earth recoveries of up to 88.4% TREY, with the Narlaby formation at Head delivering up to 93% dysprosium plus terbium extraction
  • Wudinna hosts a maiden JORC-compliant Mineral Resource Estimate of 150 million tonnes grading 470 ppm total rare earth oxides; a scoping study is being advanced
  • Investors should watch for further Narlaby formation studies aimed at assessing inclusion in the ISR portion of the Head mineral resource estimate

Pidinga and Narlaby Formation Results at Boland and Head Discovery Areas

At the Boland Mineral Resource area, Pidinga formation samples returned recoveries of up to 88% TREY, 87% neodymium plus praseodymium, 73% dysprosium plus terbium, 81% samarium, and 76% yttrium under 24-hour ambient temperature leach conditions using a 0.5 molar ammonium sulphate solution at pH 3. At the Head Mineral Resource area, Pidinga formation results reached up to 66% TREY, while three Narlaby formation samples at Head delivered peak recoveries of 88% TREY, 93% dysprosium plus terbium, and 88% samarium — figures the company describes as strongly encouraging, though ISR amenability for resource classification purposes has not yet been demonstrated for the Narlaby horizon.

Cobra's In Situ Recovery Strategy and Bottom-Quartile Cost Objective at Wudinna

Cobra's development approach at Wudinna is built around confined-aquifer in situ recovery, a low-disturbance extraction technique that the company believes could position Wudinna as the Western World's first rare earths ISR operation. The 150 million tonne, 470 ppm TREO resource underpins a planned scoping study targeting bottom-quartile production costs. The diagnostic results are intended to define metallurgical domains, assess extraction-mineralogy-permeability relationships, and support reagent trade-off analysis. The company notes that commercial recoveries, environmental performance and capital costs remain subject to integrated field validation and further engineering studies before economic conclusions can be drawn.

Narlaby Formation Conversion Study and Next Development Steps at Head

The announcement states that the Narlaby formation at Head is both permeable and mineralised, though it has not yet been demonstrated to be ISR amenable for the purposes of the existing mineral resource estimate. Cobra intends to study the Narlaby formation in greater detail to evaluate whether its mineralisation can be reclassified — in whole or in part — from open pit MRE into ISR recoverable resources. Planned next steps include operating a large-scale ISR column to replicate a proposed small-scale production study, alongside intact-core testing and permeability assessment designed to build confidence in scoping study estimates.

Wudinna Results Verified by ANSTO Testing and Reviewed by Independent Competent Person

The diagnostic testwork was conducted at the Australian Nuclear Science and Technology Organisation, and the company confirmed at the time of reissue that all results had been verified, solid assays reconciled, and reported recoveries confirmed. Metallurgical results were reviewed by James Davidson, Principal at Rendement and a Fellow of the Australasian Institute of Mining and Metallurgy. Rupert Verco, himself a Fellow of the Australasian Institute of Mining and Metallurgy with more than 18 years of relevant industry experience, also assessed the announcement. Cobra additionally holds a significant shareholding in Barton Gold following the 2025 sale of non-core gold assets for A$15 million in cash and shares.