Great Boulder Resources Ltd (ASX:GBR) is a step closer to finding the source of copper-nickel-cobalt mineralisation at the Mt Venn project in Western Australia’s Eastern Goldfields following ground survey work.
A moving loop electro-magnetic (MLEM) survey over the Eastern Mafic complex has confirmed the presence of numerous large bedrock conductors.
These show an EM response consistent with massive sulphide mineralisation and confirm the results of a recent airborne EM survey.
READ: Great Boulder Resources gets ready to find out real potential of Eastern Mafic complex
The Eastern Mafic complex sits immediately adjacent to the Mt Venn discovery, where mineralisation has been outlined over several kilometres and remains open in all directions.
Managing director Stefan Murphy said each round of exploration provided more strong evidence of the outstanding potential at Mt Venn.
“These results continue to strengthen our belief that the Eastern Mafic complex is the feeder structure and may host the higher-grade source of mineralisation within the larger Mt Venn project.
“The airborne EM survey, MLEM survey and the geochemical results are all lining up perfectly.”
An aerial EM survey being flown over the Eastern Mafic complex.
Ongoing MLEM work is progressing north to test strong airborne anomalies with coincident copper-nickel geochemistry.
It is about 15% completed and is expected to take another two to three weeks to complete.
Drilling program planned
Great Boulder is also planning a maiden reverse circulation and diamond drilling program.
On completion of the MLEM survey and geophysical modelling of the conductor plates, the company will mobilise a drill rig to the site.
It expects to start drill testing the anomalies in the Eastern Mafic complex in six weeks.
READ: Great Boulder to dig deeper at Eastern Mafic complex of Mt Venn copper-nickel-cobalt project
Mineralisation at Mt Venn, which remains open in every direction, is copper-dominant and indicative of late-stage formation within the intrusion.
The Eastern Mafic complex is being targeted because its geochemical signature suggests an earlier stage of formation, meaning it is potentially closer to the source or a feeder structure.
Positive drilling results
Great Boulder has also received positive results from drilling at Mt Venn, which is part of the wider Yamarna project.
This has identified new copper-nickel-cobalt lenses and extended existing mineralisation.
Best result was 44 metres at 0.5% copper, 0.2% nickel and 0.06% cobalt from 153 metres downhole, including 3 metres at 1.0% copper and 2 metres at 1.2% copper.
“In addition to these exceptional results at the Eastern Mafic, we have outlined extensive mineralisation immediately next door at Mt Venn.
“This known mineralisation continues to grow with every drill program and remains open in every direction.
“But we also believe it is the tail-end of the mineralised system and that there is a substantial source nearby.
"The Eastern Mafic continues to demonstrate characteristics consistent with being that source.”
Positive initial test work
The company has also received positive results from initial metallurgical trials on a composite sample from Mt Venn.
This work is testing metallurgical flowsheet options to produce separate copper, nickel and cobalt products.
Preliminary results indicate that extractions of about 90% can be obtained for copper concentrate and a nickel-cobalt concentrate under test conditions.