King River Resources is breathing new life into one of Western Australia’s forgotten goldfields, lining up drilling and geophysics at its historic Mindoolah project while eyeing a sizeable inventory of potentially gold-bearing stockpiles sitting at surface.
The historic Mindoolah goldfield, 70km north-west of Cue in WA's Murchison Province, hosts untested open pits, high-grade historical hits and 745,000 tonnes of surface stockpiles primed for immediate exploration.
King River has used state-of-the-art 3D LiDAR drone mapping and high-resolution geophysics to define the deeper structural controls that eluded early miners.
The key takeaway is a gaping chasm revealed between history as recorded and history as it actually happened.
According to official government production records from 1986 to 1989, 38,589 tonnes of ore were mined at Mindoolah during the modern open-pit era. However, when the company measured the actual excavated voids across the Le Soleil, Bertram's, Excelsior, Cundy and Mindoolah Main Reef pits, it came up with a cumulative excavation of approximately 1.08 million tonnes – a figure roughly 28 times the officially declared amount.
After accounting for 746,000 tonnes of material still in surface stockpiles and waste dumps across the tenure, roughly 339,000 tonnes remain unaccounted for, which is nearly nine times the total tonnage in the official record.
King River’s interpretation is that either a substantial volume of gold-bearing material remains on-site within the existing stockpile inventory, or the historical processing throughput was considerably larger than the paperwork suggests. Either way, the implications are significant.
The stockpiles are not theoretical. They are sitting on surface and have already returned some eye-catching assays. Grab sampling at the Excelsior stockpile complex, which alone hosts an estimated 285,630 cubic metres of potentially mineralised material, has returned results up to 10.0 grams per tonne (g/t) gold. Over at Mindoolah Main Reef, a miscellaneous stockpile returned a peak of 9.39g/t gold and grab samples from the open pit walls at Bertram’s have run as high as a gobsmacking 31.7g/t gold.
King River Resources managing director Graham Gadsby said: " The results of our recent LiDAR and volumetric reconciliation at Mindoolah are a potential game-changer for the Project. Physically, we can see that over one million tonnes of material were excavated, yet only 11% of that was ever officially reported as ore. By applying modern digital terrain modelling to historical excavations, we have identified a substantial discrepancy in the project's history.”
Notably, on top of the stockpile material, the company's technical review has identified that several key prospects have never been properly tested at depth or in the correct drilling orientation.
At Excelsior, the largest pit on the tenure, there has been no historical drilling directly beneath the pit floor, and no east-west oriented drilling has ever been conducted. At its Cundy pit, LiDAR mapping suggests the primary mineralised lodes run northeast-southwest, misaligned with the historical pit design. At Bertram's, historical drilling was sub-parallel to the interpreted lode orientation, likely understating true mineralised widths.
Le Soleil is also emerging as a compelling target, despite no historical drilling directly beneath the pit floor, with earlier drilling intersecting 2m at 2.38g/t gold from 23m depth.
In short, the company believes it is looking at a reset of the project's geology.
King River says much of the field remains largely underexplored by modern standards. Consequently, a systematic drill program has been planned for early June to target the stockpiles, running alongside a rescheduled high-resolution magnetic survey.
Data from the magnetic survey will be integrated with the LiDAR digital terrain model to sharpen deep targets beneath Excelsior and Mindoolah Main Reef.
King River says recent site works have already cleaned up historical waste dumps and improved access ahead of drilling and geophysical programs.
Mindoolah sits within the Youanmi Terrane of the Archaean Yilgarn Craton. Mineralisation in this neck of the woods occurs primarily as narrow, high-grade quartz reefs, easy targets for early prospectors and as such, the area has had a long and colourful mining history.
Gold was initially discovered in the area by a prospector named Bertram. His lease, known as "Bertram's Reward," was the first to operate on the field and underground operations in the early 1900’s returned average recovered grades of 11.4g/t gold from the Mindoolah main reef. The Mindeloo and Le Soleil workings also regularly turned in grades north of an eye-watering 30g/t gold.
Adding to the prospectivity of the area, the old timers appear to have stopped at around 20 metres depth due to water ingress, barely scratching the surface of what may be a much larger system.
Despite a punchy historical production record and a treasure trove of geological indicators screaming 'there's more gold here', Mindoolah has remained largely untouched since the goldrush era until just a few years ago.
If modern technical work can bring this high-grade system back into focus, King River may be sitting on something considerably more substantial than the old paperwork implies.
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