Polymetallic pickings; With gold coantent particularly high, the

The Estrades orebody in northwestern Quebec is a gold-rich, polymetallic massive sulphide deposit occurring within the Casa Berardi Fault zone. Although it exhibits characteristics similar to Kuroko-and Noranda-type volcanogenic deposits, the overall geometry of the deposit is atypical. While Kuroko-type deposits are generally pod-shaped, Estrades is an extensive sheet-like body. As well, what makes it especially interesting to geologists is the metal zoning: the centre of a Kuroko-type is usually enriched with copper; the Estrades core shows zinc and gold enrichment. Estrades is also unusual because in its stratigraphic position in relation to the volcanics, the deposit occurs entirely within a felsic band.

Gold content is particularly high. Probable and proven reserves on the Estrades Main zone total slightly more than one million tons grading 0.16 oz. gold per ton (5.5 grams per tonne). Added to the 10.7% zinc, 5.31 oz. per ton silver (182.1 grams per tonne), 0.94% copper, and 0.92% lead, the gold concentration makes this deposit especially attractive.

Breakwater Resources, the current owner, moved in on Estrades when Teck Corp. abandoned the project last year. Since February of this year, Breakwater has been developing the deposit as quickly as possible. In fact, the company expects to haul its first load of ore in August.

Breakwater has found a way around the high development costs that often make small, deep deposits uneconomic. Instead of building its own mill, the company will save millions of dollars by shipping ore 130 km to the Noranda Minerals mill in Mattagami. “We will be filling the void at Mattagami,” said Estrades’ mine manager, Dan Gignac.

Originally built to handle ore from Noranda’s Mattagami Lake copper-zinc mine, which closed in 1988, the Mattagami mill now processes ore from Noranda’s nearby Isle-Dieu mine. But the mill has not been running at full capacity even with additional tonnages from custom milling contracts, so the deal with Breakwater is an opportunity for both companies. The Mattagami mill will also process Estrades ore to produce a zinc/silver concentrate. But because of the high silver content, Breakwater has not found an interested North American buyer for the concentrate. As a consequence, the concentrate will travel by rail to Quebec City and then by ship to a smelter in Europe.

The Mattagami mill’s flotation cells can easily be adapted to handle the polymetallic ore from Estrades, Gignac told The Northern Miner Magazine on a site visit. The copper-lead-gold concentrate produced will be blended with Noranda’s concentrate and shipped to the Horne smelter in Rouyn-Noranda.

Beyond the confines of the Main zone, an adjoining Central zone to the east has a “mineral inventory” of 510,300 tons (463,909 tonnes) grading 0.13 oz. gold (4.5 grams per tonne), 2.77 oz. silver (95.1 grams per tonne), 0.77% copper, 0.64% lead and 6.76% zinc. Breakwater will determine the economic potential and develop a proven and probable quantity of ore in this zone by drifting into the mineralization from the main ramp.

The Estrades discovery dates back to 1985, when a weak but continuous geophysical conductor running across the property alerted joint-venture partners Golden Hope Resources and Golden Group Explorations to the possibility of a metallic deposit beneath the previously unexplored bog. To earn an interest in the project, Teck began a drill program, and on the first hole intersected seven metres of high-grade mineralization. This discovery led to detailed drilling and a production decision at the beginning of this year.

Breakwater became involved in the project in 1988, when it gained control of Noramco Mining. At that time, Noramco affiliates Golden Hope and Golden Group owned the Estrades property and Teck, as operator, had the option to back in for 50%. Breakwater purchased 9.5% interests in both juniors and negotiated with Teck for additional interest in the property. In the spring of 1989, Golden Hope/Golden Group paid Teck $500,000 to relinquish its interest and Teck also agreed to forfeit a 2% net smelter royalty, which will apply again after the owners recover $72 million in operating profits. Once commercial production begins, Breakwater will hold a 70% interest, while Golden Group and Golden Hope will retain 18% and 12% respectively.

But the move towards production has not been smooth sailing for Breakwater. In order to keep the ever-encroaching swamp from swallowing the access road, Breakwater has had to underlay the road with nine miles of geotextile matting. Several reverse circulation holes were necessary before the company could locate a suitable topographic high for the portal. Even so, huge volumes of overburden had to be removed during the frigid winter months before Breakwater found bedrock.

Fortunately, the company has its own gravel pit just four miles from the Estrades orebody, which cut road construction costs down to $1.5 million. And the excavation above the portal is in some ways a blessing — Breakwater can dump waste rock there during production.

Gauthier is also excited about exploration potential on the extreme eastern boundary of the property. In 1987, within 50 ft. of the eastern boundary, a diamond drill hole was collared on the 3,000-ft. level and intersected 0.30 oz. across 6 ft., north of the 04 Break. Although the intersection actually occurred on the old Lakeshore mine property being worked by Newfields Minerals (TSE), it was a hint that the zone might extend on to LAC’s Macassa property.

LAC recently reported encouraging values from its drifting program along the 4750 level of the 04 Break extension on to the adjacent 18-claim property of Queenston Mining (TSE). Last year LAC agreed to conduct 5,000 ft. of drifting and 15,000 ft. of diamond drilling from its own underground workings, west of the shaft. Assays are not yet available to confirm the occurrence of economic mineralization.

To date, of the three drifts that continue across the North-South fault gap, none have found ore. Under the terms of the joint venture agreement with Queenston, LAC is the operator of the project and can earn a 65% interest on the first 400,000 oz. produced from the Kirkland Lake West property.

This year, underground exploration and development will cost about $3.5 million, of which $1.3 million will be spent on underground development and $2.2 million on exploration.

Meyer says the Macassa mine has been the backbone of the community since the late ’60s, when long-lived gold mines like the Wright Hargreaves, Lakeshore, and Teck-Hughes ran out of ore, after 45 to 50 years of production. Many generations of dedicated miners have made their mark on the mine since operations began in 1933. As of June, 1990, the mine had 317 employees on its payroll.