ASX listed Tyranna Resources’ JV partner, Alliance Resources, has discovered wide intersections of high grade graphite mineralisation at the Yeltana prospect, 125km west-northwest of Whyalla in SA.
Diamond drilling results from two holes completed in August confirmed extensions to a 2017 drill hole, that returned 39 metres grading 8% total graphitic carbon from 116m down-hole.
The first new intersection came 50m down-dip of the 2017 hole and produced two separate intersections, including 17.1m @ 8.54% TGC from 148m down-hole and 21.05m at a serious looking grade of 9.28% TGC from 171.75m
Another hole, completed 230m southeast of the first, turned up 17.2m @ 5.05% TGC from 234.1m down-hole, showing the defined graphite mineralisation has both down-dip and strike continuity.
The ore system was originally identified as a strongly conductive source from a heli-borne electromagnetic geophysical survey of the companies’ Wilcherry Project JV tenements in early 2017.
Follow-up detailed ground electromagnetic surveys completed in mid-2017 tied the target down, from which the graphitic mineral deposit was then located.
The ground EM surveys showed a single bedrock anomaly that was modelled as being an exciting 600 metres wide and 1.2km long, starting some 50 -75m below surface and dipping to the southwest.
Based on the shape of the conductive target and assays received from the drilling to date, Alliance has estimated an Exploration Target of between 24.5 – 59 million tonnes grading between 5.5% - 10.2% TGC for the Yeltana graphite prospect.
The diamond drill holes were also planned to provide mineralogical samples for graphite flake size analyses to better assess the economic potential of the finished product.
The prospect area is overlain with 10-30 metres of transported cover and the rock is deeply weathered to between 70-115m depth.
According to Alliance, graphite mineralisation is hosted within a mudstone, bounded by a schist, with occasional sandstone layers and it is intruded by a granite or pegmatite intrusion.
Bedding and mineralisation dips to the southwest, meaning it lines up perfectly with the dip direction interpreted from the ground-based EM geophysical surveys.
Alliance has also utilised down-hole electromagnetic surveys inside the existing drill hole traces to allow future targeting of the most conductive zones which will contain the graphite and/or sulphide-rich mineralisation.
The Wilcherry JV between Tyranna and Alliance presently confers a 75.01% majority ownership to Alliance, with Tyranna holding the balance.
Alliance’s flagship project is the Weednanna gold deposit, located only 20km east of the Yeltana graphite prospect, where the JV partners have estimated a mineral resource of 1.1 million tonnes grading 5.1g/t gold for 181,000 ounces.
Alliance says that an assessment of the economic potential of the Yeltana graphite prospect will occur in parallel with the development of the Weednanna gold deposit.
Based on the definition of a sizeable exploration target at the Yeltana prospect, Alliance management said it will now engage graphite industry experts to help it assess the commercial viability and opportunities to develop the prospect further.
This will consist of preliminary mineralogical test work and if warranted, development of a systematic exploration drilling and metallurgical testing program to define an appropriate-sized mineral resource estimate for the prospect.
With mineralised widths going over 20m and upwards of 9% TGC, Alliance and Tyranna look to be onto something interesting in South Australia.
By Matt Birney
