Eastmain confident in Eau Claire

Drilling over the last two years and more conservative parameters used in an updated resource estimate have increased grade and deleted marginal ounces at Eastmain Resources’ (TSX: ER; US-OTC: EANRF) Eau Claire gold deposit in Quebec’s  James Bay region.

An appropriately constrained Whittle pit shell, stricter underground wireframe model and minimum 2-metre mining width were employed in the revised resource estimate in what Eastmain calls a “robust, realistic and practical approach to a potential mining scenario” at the deposit.

The result is a 57% increase in grade to 6.3 grams gold per tonne and an 18% decline in the resource to 1.3 million ounces.

“We took a much more conservative and realistic approach to the resource and the potential mineability of the deposit,” Claude Lemasson, Eastmain’s president and CEO, tells The Northern Miner.

“In the last five years you’ve seen quite a few companies issuing really good-looking resource estimates, and all of a sudden they get to a preliminary economic assessment or feasibility study and once they apply conservative parameters the resource shrinks significantly,” he says. “We wanted to make sure that the base case started with a conservative approach, so we can build on that.”

Lemasson notes that the company ended up with 20% of all the ounces in the pit and 80% in an underground scenario with a ramp.

The open-pit grade in the measured and indicated category jumped 46% to 5.9 grams gold and the underground grade increased 31% to 6.26 grams gold.

Eau Claire now consists of 4.2 million tonnes grading 6.16 grams gold per tonne for 826,000 oz. gold in the measured and indicated category, and another 2.2 million tonnes grading 6.49 grams gold for 465,000 inferred ounces.

Some of the 450 West Zone outcrop at the Eau Clair gold deposit at Eastmain Resources’ Clearwater property in Quebec. Eastmain Resources.

The estimate is based on 690 drill holes, or 274,000 metres of drilling — 78,000 metres of which were completed between 2015 and 2017.

Eastmain says the resource justifies moving ahead with a preliminary economic assessment (PEA), which it expects to finish in the first half of 2018.

In the meantime, it will complete its 15,000-metre drill program before year-end and add the data into the PEA.

Lemasson said infill drilling has expanded the company’s understanding of the structure and mineralizing controls at Eau Claire, and drilling will focus on the extension of the deposit.

“Because we understand the deposit much better, we are able to actually follow the two different types of veins we have — high-grade schist veins and quartz tourmaline veins — and we are able to follow them a little deeper,” he says. “We can focus drilling between a depth of 350 metres and 600 metres, and put that into the PEA.”

Eau Claire, 50 km from Goldcorp’s (TSX: G; NYSE: GG) Éléonore gold mine, is open at depth towards the southeast.

In August, the company reported shallow mineralization in quartz veining a kilometre southeast of Eau Claire’s 450W Zone outcrop. Drill hole 771 intersected 226 grams gold over half a metre at a 69-metre vertical depth.

“What’s interesting is that it’s in an area where we never knew there was any mineralization whatsoever, so this is a completely new target stepped away from the target that we are also investigating,” Lemasson says.

Lemasson is excited about the property’s overall potential, too, noting that Eau Claire takes up only 1 sq. km of land in the southwestern corner of the company’s 50 sq. km land package.

There are “multiple” targets on the Clearwater property, he says, some of which will be drilled this year and some next year. “It’s looking very promising, so what we may end up with is Eau Claire as an anchor deposit, with some satellite deposits that we may identify over further exploration.”