Mt Deans Project location plan in the Eastern Goldfields Lithium corridor
The licence covering the Mt Deans Project (P63/2063) was granted in the September quarter of 2019. The Project was subject to an earn-in JV with Lithium Australia NL which expired in mid-2020, resulting in the Project reverting to 100% ownership by Aruma. Aruma holds a positive view of the lithium, tantalum and REE potential of the Project area with previous work having identified swarm pegmatites over 1km in length.
The Mt Deans Project covers an area of 1.44km2 in the Mt Deans pegmatite field, which is part of the Eastern Goldfields Terrane of the Yilgarn Craton. The Project is located approximately 190km north of the Esperance port, 170km south of Kalgoorlie and approximately 10km south of the mining town of Norseman (below).
Mt Deans Lithium-Tantalite Project, with pegmatites and drilling section
The geology at Mt Deans presents as potentially analogous to that of Liontown Resources’ (ASX: LTR) world-class Kathleen Valley Lithium-Tantalum Project in the Mid-West region of WA, where the lithium mineralisation is hosted within spodumene-bearing pegmatites.
The Mt Deans area has a swarm of 71 recognised pegmatites covering 4.5km by 1.5km trending north, north-west (as discussed in Amit Eliyahu’s University of Western Australia thesis on the Mt Deans pegmatites). The pegmatites range from 500m to 2,000m in length and 0.3m to 7.5m thick, with some 20m thick.
The pegmatites have an upper portion quartz-poor, feldspar-rich marginal layer, which is where most of the cassiterite and tantalum is found. The pegmatites in the project area are considered later (deeper) and are suggested to be closer to a main ‘cauldron’ or ‘chamber’ that may host spodumene-rich material, potentially suitable for direct shipping.
Aruma completed the first phase of drilling at Mt Deans in February 2022. Drilling comprised 1,156 metres of RC drilling in eight holes. It is the first phase of a planned 3,000 metre maiden drilling program at the Project.
The first phase of drilling was designed to confirm the presence of a thick pod of pegmatite interpreted from convergent dips seen in historic drilling, and to intersect an interpreted pegmatite chamber or ‘cauldron’.
Drilling delivered positive initial results. Pegmatite was intersected in every hole, with a highlight being a near-surface 25 metre thick, vertical body of solid pegmatite, from a depth of just 17 metres. Drilling indicated a strike length of up to 500 metres, which remains open at both ends. The targeted lithium mineral, spodumene was visually identified in the drill cuttings as were tin and tantalite.
Details of results and exploration activities are available via the Company’s ASX announcements.
Mt Deans Cross Section of interpreted pegmatite results
Samples from drill holes MDRC 6 and MDRC 8 from the main body of pegmatite, from Aruma’s drilling at Mt Deans, are shown in Figure 4 below.
Drill chips showing the lithium minerals in the drill holes MDRC 6 and 8
Drill chips showing the lithium minerals in the drill holes MDRC 6 and 8
Previous exploration identified swarm pegmatites over a strike length of 1 kilometer. High-grade rock chip samples have previously been reported from the Project area, with lithium oxide results as high as 2.1% Li2O, and tantalum (Ta) as high as 556 ppm Ta2O5 (tantalum pentoxide) plus other rare earth elements (Table 1) (ASX announcement, 24 March 2021).
Table 1: Rock Chip samples from Mt Deans ((ASX announcement, 24 March 2021).
Table 2: Drilling Results Table based on visual logging.
