Special Report: Impact is confident about the perspectivity of the Blackridge gold field in Queensland and has moved to lock down the majority of the historic area.
It has lodged two new applications for exploration licences that along with its existing exploration and mining leases takes its total landholding up to 150sqkm.
This will give Impact Minerals (ASX:IPT) ownership of about 90 per cent of Blackridge, which forms the southern half of the greater Miclere-Blackridge area that produced over 300,000 ounces of gold in the late 1800’s and early 1900’s.
Impact has been actively exploring at Blackridge since mid-2018 after reaching an option agreement with Rock Solid Holdings Pty Ltd to acquire a 95 per cent interest in one exploration licence and four mining lease applications.
Two successful bilk sampling programs returned an average grade of 0.36 grams of gold per cubic metre over significant strike lengths.
This also demonstrated that the area holds large volumes of very weathered oxide material that is not only soft and very easy to dig but also contains easily recoverable gold.
Drilling by previous explorers also demonstrated the presence of gold bearing units above the basal two metre zone that had been mined historically as well as the gold-bearing conglomerates that stretch down dip for over 2km of strike to a depth of just 100m.
However, the option lapsed in late 2019 after Impact was unable to renegotiate the inclusion of trial mining and Rock Solid subsequently allowed the exploration licence to lapse earlier this year. This area is now covered by one of Impact’s licence applications.
Rock Solid still retains the four mining lease applications.
Gold Exploration Strategy
Gold mined at Blackridge was in the form of coarse nuggets mined most underground from a two-metre thick conglomerate unit.
Conglomerate gold refers to nuggets hosted in rock containing rounded grey quartz pebbles and other minerals. The world’s most productive gold region, South Africa’s Witwatersrand Basin, is famous for this geological formation.
Impact noted the coarse nature of gold mineralisation at Blackridge requires very large samples to accurately estimate the gold grade.
This has hindered modern exploration as assays from standard narrow diameter reverse circulation (RC) drill holes would not be large enough to allow for an accurate estimate of the true grades.
The company’s new licence applications cover ground previously tested by RC drilling at Hard Hill and by both RC and large diameter Calweld drilling at Pewt’s Hill.
It noted that the larger samples returned by Calwld drilling demonstrated a significant increase in the grade, thickness and lateral extent of gold mineralised intervals compared to adjacent reverse circulation drill holes.
As a result, Impact believes that previous work at Blackridge may have significantly underestimated the amount of gold present at the project and that higher grades may be delineated with an appropriate sampling methodology.
It added that it is following Canadian company Novo Resources Corporation’s progress in pioneering techniques and procedures for mining nuggetty conglomerate-hosted gold in the Pilbara region closely and is formulating plans to emulate this work at Blackridge.
On ground work is expected to begin once the licences are granted later this year.
This story was developed in collaboration with Impact Minerals, a Stockhead advertiser at the time of publishing.
This story does not constitute financial product advice. You should consider obtaining independent advice before making any financial decisions.