THE DRILL SERGEANT: Lithium Australia (ASX: LIT) declared identification of lithium pegmatite swarms at Medcalf, part of the company’s Lake Johnson project in the lithium-prospective Yilgarn Block of Western Australia.
The region is host to other major lithium deposits such as Earl Grey (Kidman Resources and SQM) Mt Marion (NeoMetals, Gangfeng and Mineral Resources) and Mt Cattlin (Galaxy).
Lithium Australia noted all of these deposits, as well as Medcalf and Lithium Australia’s nearby Mt Day prospect, have similar geological features whereas the pegmatites emanate from nearby fertile granites and are injected into adjacent greenstones.
Lithium Australia made the Medcalf discovery via an initial geological reconnaissance program it conducted after interpretation of aerial photographs highlighted the potential for multiple pegmatites in 2017.
Outcropping pegmatites were identified at Medcalf during subsequent field inspections in April 2018 and subsequent geological mapping, and sampling confirmed some of these pegmatites as LCT (lithium, caesium, tantalum) types.
Pegmatite swarms containing spodumene mineralisation outcrop in a zone of some 100 metres by 50 metres in area, within a larger area of pegmatites of 250m wide by 500 metres long.
The company acknowledged that the initial rock-chip samples are prospective with grades ranging from 3.07 per cent lithium oxide (Li2O) up to 4.78 per cent Li2O and one spodumene only specimen sample grading 7.15 per cent Li2O.
LIT completed a field inspection that identified a pegmatite swarm centred upon the highest hill in the area, where at least five pegmatites were located, and all containing spodumene.
The company described the prospect area to have moderate to low topographic relief and potential exists for additional pegmatites under cover with the main target area it visited containing pegmatites presenting as a dyke swarm comprised of numerous pegmatites in a zone about 250m wide and at least 500m long.
Outcrops of individual pegmatites range from about 2m to 10m in width and 50m to 150m in length. The pegmatites appear to dip at moderate to steep angles towards the southwest and appear to have true-thicknesses of about 5m and are relatively close together with only a few metres separating individual pegmatites.
“The occurrence of LCT pegmatites adjacent to granites at Medcalf has regional geological significance,” Lithium Australia managing director Adrian Griffin said in the company’s announcement to the Australian Securities Exchange.
“The pegmatites occur in the same greenstone sequence that abuts the same granite complex at Lithium Australia’s Mt Day prospect, 45 kilometres to the north-east.
“Both locations have significant lithium mineralisation and there is good potential for locating further LCT pegmatites below cover, within the Lake Johnson project area.”