The big-time potential of St George’s Mt Alexander nickel-copper project in Western Australia has been enhanced by the discovery of high-grade mineralisation at depth.
St George reported in mid-April that drill hole MAD199 had returned a 10.96-metre interval of nickel-copper sulphides from a 333.6-metre downhole while testing an electromagnetic (EM) conductor.
The result (assays were pending) was the deepest occurrence of massive nickel-copper sulphides drilled along the Cathedrals Belt at Mt Alexander, and was also the most western occurrence.
St George executive chairman John Prineas says MAD199 has confirmed the prospectivity of the Cathedrals Belt for further high-grade mineralisation, particularly at depth and to the west.
“Hopefully we are getting close to finding the big prize,’’ Prineas tells Australian Resources & Investment.
He explains that previous exploration along the Cathedrals Belt discovered shallow deposits across a strike length of 5.5 kilometres.
“It’s high grade nickel, copper, cobalt and platinum group metals. It is wonderful stuff starting 30 metres below surface,” Prineas says. “But they are relatively small. While we are still confident that we can monetise those because they are shallow and will involve low capital expenditure, the real prize has been to find bigger deposits at depth.
“That’s what we have been doing for the past 12 months. MAD199 was a breakthrough because it hit high-grade nickel and copper at depth.”
Prineas says MAD199 has confirmed the concept that St George has been chasing – high grade mineralisation at depth.
“We know this intrusive system goes for at least 5.5 kilometres across the Cathedrals Belt, so we have got a fantastic target horizon to keep chasing and finding more mineralisation,’’ Prineas says.
The deep conductor tested by hole MAD199 was identified by downhole EM (DHEM) survey work, with DHEM taking drill targeting on the Cathedrals Belt beyond the 300-metre depth possible with surface-based EM surveys.
“EM is a wonderful tool to find nickel sulphides. But from surface, its effectiveness is limited,” Prineas says.
“Finding the deeper stuff is a bit trickier. We know that we have pretty much screened the top 300 metres and know what is there, and what’s not there.’’
“But at depth, you really have to drill and conduct DHEM to light up the conductive targets. That is exactly how we found the MAD199 (conductor) section.”
Prineas says the Mt Alexander mineralisation is a rare combination of nickel, copper, cobalt and platinum group metals not seen elsewhere in Australia.
While chasing down the big-time potential of Mt Alexander remains the company’s main focus, St George also has a drilling campaign planned in May/June on tenements it picked up 12 months ago in the Paterson Province of WA – home to the recent copper/gold discoveries at Winu (Rio Tinto) and Havieron (Newcrest/Greatland Gold).