Maiden drilling on two prospects at St George’s Ajana project in Western Australia has turned up trumps, with significant widespread and shallow zinc-lead-silver mineralisation seen in an untested play concept for the area.
The company says it is now planning more drilling through a vast crop of highly-prospective targets with a similar fingerprint of gravity and/or magnetic anomalies.
The best assays results from its 12 reverse-circulation (RC) drilling campaign revealed high-grade mineralisation at the Perseverant prospect of up to 1m at 4.22 per cent zinc and lead, with up to 8.81 grams per tonne silver. Additional assays are expected to return from the four follow-up diamond drillholes in four to six weeks.
Perseverant is on a 25km-long magnetic anomaly, with features thought to represent a buried intrusive aligned with north/north-west-trending faults. It is covered by shallow overburden and was tested blind in the absence of any outcrop.
St George says rock samples confirm that the base metal mineralisation is hosted within high-grade metamorphic sediments, intermediate volcanics and pegmatitic intrusives. The drillbit only tested a comparatively small area of 2.2km-by-2.5km, mostly at the northern tip of the anomaly.
Management says that in combination with the high success ratio of the drillholes and the extensive depth range of mineralisation, there is significant upside potential to be realised within its current permits and at others under application.
St George’s Catalina prospect had a different coincident gravity and magnetic signature and was drilled by one RC hole and one diamond drillhole. The latter returned core that had intense haematite alteration beginning at the unconformity of the overlying sediments into the host rock through an interval from 43m to 95m downhole.
Management says it raises the possibility that it represents an alteration halo above a mineralised orebody and that follow-up drilling closer to the centre should resolve the puzzle.
St George Mining executive chairman John Prineas said: “The exciting initial drilling results at Ajana are located in a previously explored area, beneath shallow overburden. It is a blind discovery – a credit to our technical team and their use of modern geophysics and other exploration technologies. Our corporate strategy includes identifying high-leverage greenfields opportunities in stable jurisdictions and it is very pleasing to see this strategy deliver immediate success at Ajana. It is early days but the signs are there that this discovery could evolve and result in the definition of significant mineralisation.”
The results of drilling appear to have revealed the presence of a new mineralisation play concept not seen before in the area known as the historic Northampton Mineral Field. When mining took place in the area between 1850 to 1973, the high-grade zinc-lead-copper sulphides were outcropping vein-hosted base metal deposits within or adjacent to dolerite dykes intrusive to the Proterozoic granitic gneiss inlier.
The new style of mineralisation intersected by St George suggests unconformity-related sedimentary-hosted deposits in cross-cutting vein sets, indicating a late-stage event.
Similar analogues occur in WA at Galena Mining’s Abra deposit in the Gascoyne region, where that company has a resource of 33 million tonnes at 7.1 per cent lead and 17g/t silver and an updated life-of-mine plan producing lead metal at 93,000 tonnes per annum and silver metal of 553,000 ounces annually.
Another analogue is Rumble Resources’ Earaheedy deposit, with a resource of 94 million tonnes at 3.1 per cent lead and zinc and 4.1g/tonne of silver emerging as a large-scale, low-cost open-pit mining proposition, 100km north of Wiluna. The analogues signal the possibility of a major find at Ajana.
St George’s initial focus at the project was nickel-copper-platinum group elements (PGE) mineralisation and it remains steadfast in pursuing it below the depth of current drilling and at several untested magnetic anomalies.
Planned current and future work consists of continued landholder engagement to allow access for exploration activities, heritage assessment for drill rig access to the Catalina prospect, a detailed aeromagnetic survey to delineate targets in the northern permit, petrology and mineralogy of drill samples to refine the new style of mineralisation, receiving remaining assays, assessing pathfinder elements to target new drill leads and to schedule further drilling in the last quarter of this year.
With the drillbit about to turn again in the prospect-laden area, St George spectators should be salivating for more discoveries in the very near future.
Is your ASX-listed company doing something interesting? Contact: matt.birney@businessnews.com.au
By Gary Kjellgren
