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Lithium–Caesium–Tantalum (LCT) Exploration

Ardea's tenement portfolio covers more than 4,400km² and is one of the largest land holdings over nickel-hosting komatiite ultramafic stratigraphy in Australia. The significant land holding is also prospective for other economic mineralisation including Critical Minerals such as Lithium-Caesium-Tantalum (LCT) elements and Rare Earth Elements (REE). These compelling magmatic nickel sulphide and Critical Mineral opportunities are being evaluated for their exploration potential.

Of particular significance, exploration over the last 12 months has identified REE and LCT settings in association with nickel laterite occurrences.

The ongoing KNP Goongarrie Hub feasibility work streams continue to be the Ardea's priority. However compelling Critical Mineral and nickel sulphide exploration opportunities will also continue to be evaluated.

Managing Director and CEO Andrew Penkethman noted:

“Ardea’s strategic tenement portfolio in the Eastern Goldfields of Western Australia remains underexplored, due to the historic focus on the globally significant KNP nickel-cobalt laterite resource.

With Ardea’s multi-element analysis of all exploration and project development samples, we are consistently seeing LCT and REE exploration opportunities. With the expansion of the technical team during 2022, we are now able to give these opportunities the exploration effort they warrant. The initial step has been to retain highly regarded consultants CSA to complete a review of our full Eastern Goldfields tenement portfolio for LCT and REE opportunities, in conjunction with internal assessments of nickel sulphide potential.

Whilst KNP feasibility study work and advancing the Goongarrie Hub towards development as a major source of sustainable and ethical nickel-cobalt battery mineral supply is the main priority, Ardea is mindful of the significant value that exploration success can generate for the Company. On this basis, both feasibility study work and exploration on compelling targets will continue.

In striking this balance, Ardea will maximise both development and exploration of Critical Mineral opportunities from its entire tenement portfolio and looks forward to keeping all stake holders informed on Company progress.”

Ardea has conducted an initial assessment of pegmatite hosted Lithium-Caesium-Tantalum (LCT) potential. The assessment of the KNP tenement package included a ranking for rare-element LCT pegmatite potential based on geological setting and known pegmatites. The highest ranked target is the Perrinvale Project, where multiple pegmatites have previously been mapped and several reconnaissance rock chip samples recently taken and submitted for assay (results awaited). Ardea also notes the ongoing rare-element LCT pegmatite exploration from several other ASX listed companies around the Company’s Perrinvale tenure.

Other priority areas were the Ghost Rocks, Highway and Goongarrie project areas. Follow-up reviews were also recommended over tenements in the Yerilla Hub and Kalpini Hub including Bulong.

Essentially any tenement located over an Archaean greenstone belt and within 10km of an interpreted or known rare-element LCT pegmatite source granite (or in an area where potential source granites are likely to occur) was considered as having some potential for rare-element LCT pegmatites. The priority areas were selected due to the presence of interpreted source granites proximal to these tenements and any known LCT pegmatites in the region (notably south of Perrinvale). The next steps for the priority areas are to review internal and open-file data for previous recorded pegmatites, assessing if they are prospective for LCT mineralisation and completing onground mapping and sampling.

In 2023, a single diamond drillhole, AHID0024, was made at the Highway Project. The drillhole was part funded by the Geological Survey of Western Australia’s Exploration Incentive Scheme (EIS), targeting the western basal contact of the Walter Williams Formation.

AHID0024 returned results including:

  • Lithium-caesium intrusives with very high rubidium were identified in the EIS drill hole. Along with historic drill holes at Highway, a highly fractionated fertile Lithium-Caesium-Tantalum (LCT) mineral system is confirmed.
    Significant intersections in AHID0024 include:
    • 21.2m @ 0.23% Li₂O, 945ppm Cs, 1,237ppm Rb from 406.8m
      including 3.45m @ 0.34% Li₂O, 4,108ppm Cs, 4,772ppm Rb from 409.1m
    • 0.85m @ 0.34% Li₂O, 3,392ppm Cs, 4,222ppm Rb from 368.75m
    • 0.95m @ 0.15% Li₂O, 3,000ppm Cs, 4,830ppm Rb from 390.85m
  • Multiple fertile intrusives identified at Highway
    Based on the geological model generated from the EIS hole:
    • The lithium-caesium-rubidium style anomalism discovered in the AHID0024 fresh drill core has now been identified in intermediate-felsic porphyries within the weathered regolith throughout the Highway Project, with highest-grade zones on the biotite-rich intrusion margins.
    • Review of historic drill holes at Highway identified eleven holes with intersections >0.1% Li₂O, with the highest intersection 2m @ 0.68% Li₂O, 1.43% Rb, all within the oxidised weathered profile.
    • Recent Ardea mapping at Highway and Ghost Rocks has identified and sampled numerous prospective LCT intrusive outcrops including pegmatites, with assay results from Highway pending.

For details see ASX release 21 August 2023, ASX release 15 December 2023 & December 2023 Quarterly Report.