Yilgarn Craton projects

Lithium Australia is involved in four projects within the Yilgarn Craton in Western Australia, where public infrastructure includes roads, rail and power. Those projects include:

  • the Coolgardie Rare Metals Venture (‘CRMV’) with Focus Minerals Limited (‘FML’) – LIT 80%, FML 20%;
  • Ravensthorpe (Cocanarup) – LIT 100%;
  • the Seabrook Rare Metals Venture (‘SRMV’) at Lake Seabrook, with Tungsten Mining NL (‘TGN’) – LIT 80%, TGN 20%, and
  • Greenbushes – LIT 80%, private 20%.

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The CRMV*

The CRMV, an initiative of LIT and FML, focuses on areas of pegmatites 15 km south of Coolgardie.

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Waste dumps from prior mining at Lepidolite Hill comprise around 400,000 tonnes of lepidolite-rich material. Recent proof-of-concept processing by LIT, under the aegis of its alliance with Strategic Metallurgy, has produced battery-grade Li carbonate from that material.

Ravensthorpe (Cocanarup)

LIT’s Ravensthorpe Li pegmatite project focuses on Li and rare metals within the Cocanarup pegmatites, which are some 20 km southwest of the historic mining centre of Ravensthorpe.

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The Cocanarup pegmatites were reported in 1900, during the same phase of prospecting activity that led to the discovery of the Mt Cattlin pegmatites nearby (the latter are a rich source of spodumene and tantalum). Currently, ASX-listed General Mining Corporation Limited is re-evaluating the Mt Cattlin mine with a view to bringing operations back on line.

LIT owns the rights to a large proportion of the Cocanarup pegmatite field, which comprises three discrete pegmatite occurrences that intrude the greenstones of the Yilgarn Craton. These occurrences are the Quarry Pegmatite, Horseshoe Pegmatite and Eastern Pegmatite.

Quarry Pegmatite

So named because of a small working at its northern end, it consists of two bodies that together outcrop for more than 1400 m along a north-south axis. Mapping by previous operators shows that the unit is between 15 and 40 m wide with a shallow, 20-degree dip to the west. Exposures in the quarry contain purplish lepidolite and coarse-grained rosettes of zinnwaldite (a Li mica), along with quartz and feldspar.

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Rosettes of zinnwaldite in contact with feldspar.

Horseshoe Pegmatite

With dimensions of 700 m by 500 m and a thickness of between 40 and 100 m, this is a U-shaped body in outcrop. Previous mapping observations reveal that the unit contains abundant masses of lepidolite, while recent field inspections have confirmed the presence of lepidolite masses at surface, where they weather to a pinkish colour.

yilgarn-craton-projects6 Lepidolite-rich boulder at the Horseshoe Pegmatite.

yilgarn-craton-projects7 Irregular outcrop of the Horseshoe Pegmatite marked by changes in vegetation.

Eastern Pegmatite

Exposed discontinuously for more than 2000 m along the eastern edge of the tenement, the Eastern Pegmatite has mapped thicknesses between 10 and 70 m. As with the Horseshoe Pegmatite, there are no fresh exposures; however, field observations indicate that the body contains rich segregations of zinnwaldite.

Looking west across the outcropping Eastern Pegmatite. Looking west across the outcropping Eastern Pegmatite.

Samples of zinnwaldite and lepidolite – taken by LIT from historic excavations in the Quarry Pegmatite, as well as other areas in the region – are currently being prepared for leach testing and carbonate production. Meanwhile, the Company will undertake regional geochemical surveys to locate further concealed pegmatites.

The SRMV

This project centres on Li pegmatites located 60 km north-east of Southern Cross. Regionally, the pegmatites – which are associated with tungsten skarns – contain lepidolite, beryl and tourmaline. Emplacement of the pegmatites appears to be associated with a regional shear zone that flanks tungsten mineralisation in the north-east and the pegmatites in the south-west.

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This venture gives LIT immediate access to prospective areas held by TGN, as well as pegmatite occurrences on adjacent exploration licence applications.

While TGN retains the project’s tungsten rights, all other elements are vested in the SRMV, with TGN free-carried to the point at which a decision is made to undertake a feasibility study. Subsequently, the venture becomes an 80/20 (LIT/TGN) contributing joint venture.

Greenbushes (E70/4690 under application)

LIT’s Greenbushes project abuts the world’s largest Li mine, operated by Talison Lithium P/L (‘Talison’). At present, Talison’s mine – which produces Li ore of the highest grade – supplies more than 30% of current global Li requirements and 75% of Chinese demand. The Company’s Greenbushes project area covers a 50 km structural trend containing numerous pegmatite swarms, among them the Koala Road pegmatite, which has marked similarities to Talison’s Greenbushes pegmatite. yilgarn-craton-projects10 *LIT will use its experience at the CRMV (and other occurrences) to develop field-based techniques for real-time analysis of the light elements Li, beryllium and boron, which together are the signature of Li pegmatites. This will be done in conjunction with SciAps, the US developer of laser-based analytical equipment. Successful development of SciAps’ LIBZ® analytical techniques for pegmatite exploration has the potential to reduce the time and cost involved in locating concealed Li ore bodies.