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Osisko looks for Windfall Lake's 'giving hand'

"Like fingers leading to a hand", Quebec-focused Osisko Mining is searching for the mineralising source of the rich gold mineralisation it is defining at Windfall Lake, in the Quebec-portion of the Abitibi greenstone belt near Urban Township, says CEO John Burzynski.
Osisko looks for Windfall Lake's 'giving hand' Osisko looks for Windfall Lake's 'giving hand' Osisko looks for Windfall Lake's 'giving hand' Osisko looks for Windfall Lake's 'giving hand' Osisko looks for Windfall Lake's 'giving hand'

Like fingers on a hand, Osisko Mining is searching for the mineralising source at Windfall Lake

Henry Lazenby in Beaver Creek, Colorado

The company is nearing the end of an unprecedented marathon one-million-metre drill campaign at Windfall Lake and when the company closes the data books in December, the planned following resource update would likely show more grade and resource upgrades, Burzynski said during the Beaver Creek Precious Metals Summit in Colorado.

"Drilling at Lynx has been spectacular. It will bring the average resource grade up to the 8-9g/t range," he said.

While the focus was initially on resource definition drilling, "we keep finding new zones".

"The mineralised trends we've delineated to date look like fingers leading to a hand, but we've not yet reached he hand," he said.

The company published two resource estimates last year on the Lynx deposit that, importantly, showed indicated and inferred resources grow in parallel, as well as at improving grades.

The five mineralised zones currently hold indicated resources of 754,000oz gold grading 8.17 grams per tonne in 2.87 million tonnes; and an inferred resource of 2.37Moz grading 7.11g/t in 10.35Mt.

The company plans to have a resource update completed by February next year. Burzynski pointed out the Triple 8 discovery at 1.5km deep, would not be included in the resource update, "but could add 1.5-2Moz in the future".

The Urban Barry greenstone belt contains mafic to felsic volcanic rock units and is cross-cut by several east-trending and east-northeast trending shear zones that delineate major structural domains. The most significant gold mineralisation defined to date is currently known for a vertical extent of about 1,200 in four zones, including the Main Zone (Zone 27, Caribou and Mallard), Underdog, Lynx, and F-Zones.

The company reported a new discovery in July last year called the Triple 8 Zone. Osisko is currently targeting these deeper-lying zones, vectoring towards deep felsic stock that is thought to have been driving mineralisation at Windfall Lake.

"We're in the Star Trek-phase of drilling now because no one has gone there before," Burzynski said. "We're starting to see indicator minerals of proximity to the heat source. We still have lots to go to reach 3.5km deep; watch this space."

Many catalysts

Windfall Lake is an intrusion-related gold system, a relatively newly defined gold deposit class, which defines magmatic-hydrothermal systems where gold mineralisation is hosted mainly within the intrusions or in the immediate wall rocks of these intrusions. The porphyry intrusions in the Windfall Lake area are likely the source and a major factor controlling the occurrence of gold mineralisation.

"I like to use the analogy of a hand being placed in a bucket of water. If you dip your hand and find gold on the one side, chances are good you'll have gold mineralisation on the other side too," Burzynski said.

Following on from positive bulk sample results earlier this year from Lynx and Zone 27, Osisko is currently building a ramp towards the Lynx Zone for another round of bulk sampling. "What we're seeing underground is a little better than what wire frames showed."

The exploration focus will also broaden to test regional targets, including the Osborne Bell and Fox targets. "We're going to start increasing our step-out drilling next year to 400m-plus fences because we just continue to hit mineralisation everywhere we drill."

The near-term catalysts include the results of a second bulk sample at Lynx by November, a continuous flow of infill and expansion drill results, the results from deep exploration and a Windfall resource update early next year pulling all deposits together, except for the deeper-lying targets that require further work to be properly understood.

The company is working towards completing a feasibility study in 2020.

"We expect Windfall will become one if the great Canadian Archaen long-lived gold deposits. It's a district-scale project. We have 2, of prospective property; chances are there are other mineralised occurrences too."

Burzynski said back-of-envelope calculations, based on an expected higher resources grade, current exchange rates and at US$1,500-plus gold, derived an IRR for Windfall of 80%-plus compared with last year's after-tax PEA result of 32.7%, with an NPV of C$413.2 million.

The company has lots of cash in the bank, currently sitting at about $200 million.

Osisko's Toronto-quoted equity (TSX:OSK) has gained about 37% in the past 12 months to C$3.25, after achieving a 12-month high at $3.90 earlier this year. Osisko has a market capitalisation of $883.9 million.


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