Australian Critical Minerals Updates Cooletha Lithium Project and Rankin Dome Exploration Progress

26 September 2023 14:38

Australian Critical Minerals (ASX: ACM) has provided an update on its Cooletha Lithium Project and ongoing exploration at Rankin Dome, highlighting significant developments in both areas.


Figure 1: The location of the Cooletha Lithium Project in the Pilbara region, Western Australia.

Cooletha Lithium Project Sampling

Phase 1 Sampling marked a significant milestone for the Cooletha Project, spanning approximately 65 square kilometres and resulting in the successful collection of 251 rock samples, offering invaluable insights into the region’s geological composition.

Consulting geologists closely scrutinised the collected samples, identifying four priority areas within the Project, characterised by unique fractionation textures and spodumene content, indicating significant lithium potential.

The four pegmatite prospects named Bloodwood, Echo Valley, Burnt Ridge and Billy Creek have been identified as priority future work areas.

The pegmatites occur as dykes and broad pavements striking for several hundred metres and often with substantial widths. The pegmatites are hosted in the Tambourah Monzogranite which is a large domal batholith and part of the Split Rock Supersuite which regionally hosts lithium and tantalum bearing pegmatites.


Figure 2: Four lithium pegmatite prospects have been identified as priority areas during recent sampling at Cooletha.

A notable discovery is the presence of Billy Creek Pegmatites, which extend below the basal unconformity of the Fortescue Group, thereby expanding the lithium pegmatite target size, prompting Australian Critical Minerals to schedule a reverse circulation drilling campaign for further investigation.

Additionally, the exploration has revealed manganese-rich shales, with thicknesses ranging from 30 centimetres to 1 metre, near the base of the extensive Fortescue Group in Eastern Cooletha, presenting an additional mineral opportunity.


Figure 3: Pegmatite sills and irregular bodies at Bloodwood.

Strategic Location

Encompassing over 100 square kilometres of lithium prospectivity, the Project is strategically positioned in the heart of the Pilbara lithium district.

This region has gained recognition for hosting significant lithium discoveries, including Pilbara Minerals’ Pilgangoora Lithium Project, MinRes’ Wodgina Lithium Project, and Global Lithium Resources’ Archer Lithium Deposit at Marble Bar.

Moreover, Cooletha is conveniently located just 30 kilometres south of the Tambourah Lithium Project, owned by Trek Metals (ASX: TKM). Trek Metals has recently initiated its inaugural 3,800-metre drill campaign, spurred by promising rock chip results that indicate lithium concentrations of up to 3.02% Li2O.

Rankin Dome Project

At the Rankin Dome Project in the Yilgarn region, a comprehensive exploration effort has been underway.

A shallow auger soil program consisting of 249 holes was recently completed, strategically covering the northwestern section of the previously reported rare earth element (REE) anomaly.

This program was designed to enhance the Company’s understanding of the REE anomaly’s geometry and provide essential orientation data for future drilling initiatives.

The sampling process followed standardised procedures, with intervals of 1 to 2 metres sampled to ensure a robust geological interpretation once assay results are obtained.

Given the limited outcrop in the area and the consequent lack of bedrock depth information, the grid program included drilling one in ten holes to refusal to gain deeper insights, including bedrock depth.


Figure 4: RC Drillhole collar locations Rankin Dome

Notably, the work performed by Kula Gold (ASX: KGD) yielded strongly anomalous results on sample lines with varying orientations. To mitigate interpretation biases resulting from these orientations, Australian Critical Minerals increased sample density and employed a 100-metre by 100-metre grid approach, with auger samples having been collected and submitted for assay, with results eagerly anticipated.

Currently, a 900-metre reverse circulation (RC) drill program is underway in the northwest section of Rankin Dome, where bedrock lies close to the surface. This RC drilling campaign is strategically positioned to test areas exhibiting REE anomalism in soils, further advancing the Project’s exploration endeavours.

Encouraging Observations

Australian Critical Minerals’ Managing Director Dean de Largie said the Company is pleased to update its shareholders regarding the encouraging observations from the Cooletha Project.

“Our field investigations have increased the potential area of prospectivity for lithium pegmatites, identified four prospects described as having large pavements of pegmatites and identified shale-hosted manganese,” he said. 

“Whilst lithium exploration will remain our priority, the addition of manganese to our portfolio of green energy commodities will be received well by our shareholders. As foreshadowed previously, Rankin Dome has progressed further with additional shallow auger sampling completed and RC drilling currently in progress.”

ACM’s Australian Stock Exchange-listed share price is currently trading at 28c (1:45 pm UTC+ 8 hours).

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