Search for new reserves keeping majors occupied

While Falconbridge Ltd.’s exploration programs are countrywide, the major exploration project in the Sudbury region is the Thayer Lindsley (TL) underground exploration program. The 16-ft. diameter shaft, the heart of the project, has recently been completed to a depth of 5,500 ft. and two crosscuts are being driven to establish diamond drill stations. These headings are at 4,300 ft. and 5,200 ft. below the shaft collar.

Drilling is scheduled to start in August. Next in importance is the probing for downdip extensions of the Craig and Fraser orebodies and $2 million has been budgeted for 1991 diamond drilling. Finally, and still within the Sudbury region, drilling for base metal mineralization of the Errington-Vermillion type is continuing in the meta-sedimentary rocks of the central Sudbury Basin. Drilling has been in progress for the last two years and $4.6 million is to be spent this year. At the time underground development of the Errington and Vermillion mines ceased in 1957, ore reserves were quoted at 17.8 million tons grading 1.10% copper, 1.06% lead, 3.92% zinc, 0.022 oz. gold and 1.58 oz. silver per ton. It proved to be extremely difficult to make a clean separation of the several mineral components with the technology that existed at the time. In conjunction with the then-prevailing low metal prices, these metallurgical problems compelled suspension of active operations.

In the Kidd Creek area, Falconbridge is preparing to explore in the vicinity of the old Kam Kotia copper producer. The Dundonald project, also in the same general area and not too distant from the metallurgical plant, will be continued this year. Significant copper and zinc values were returned from recent diamond drilling at this prospect.

According to John Harvey, president and chief executive officer of Hemlo Gold Mines (TSE), if the transfer of Noranda’s gold properties to Hemlo Gold goes ahead, and this appears most probable, then the three senior projects for Hemlo’s attention in Canada in 1991 will be Harker Holloway, Brewery Creek and the Glimmer properties.

Harker Holloway is at the feasibility stage and $5 million is budgeted for definition drilling during the current year. Earlier estimates of probable reserves were quoted at 4.7 million tons at a grade of 0.24 oz. gold and this figure is expected to have been increased as a result of later work. The Glimmer property is in the Matheson area and $500,000 is to be spent on early-stage drilling.

Hemlo’s No. 2 project in Canada, Brewery Creek in the vicinity of Dawson City, Yukon, is also at the feasibility stage and $4 million is scheduled for this year’s drilling. Probable reserves are in the range of 10 million tons at a grade of 0.05 oz. gold.

At the Hemlo mine itself, surface drilling is to probe for downward extensions of the known orebody entailing holes in excess of 4,000 ft. in length.

Despite mining operations and exploration programs the world over one of the more uncommon exploration targets of Placer Dome (TSE) is underground and at one of its original properties. According to Ray Church, Campbell mine’s chief geologist, one of the early theories was that there would be no values in the ultrabasics that underlie a large part of the Campbell property. There was no drilling of significance in this formation until recent times. Just over two years ago surface drilling intersected gold values in the ultrabasics in the course of routine exploration drilling and this was followed up with detailed drilling from the mine’s first level. A lenticular oreshoot 80×4 ft. wide was delineated and eventually mined out. Extensions to this same shoot and several other unrelated intersections are to be investigated down to the third and fourth levels this year.

Progress is slow as the workings are close to surface and can only be worked during the summer months. The grade of the ore mined from the new discovery was 0.8 oz. gold. More of the same is confidently anticipated. Corona’s (TSE) exploration activities in Eastern Canada are in a standing pattern this year with practically all attention directed toward Eskay Creek in British Columbia and to the company’s interests in Nevada. Even at Eskay Creek, the greater part of the underground exploration and trial mining program has been completed, says Exploration Vice-President Tony Ransom. This program was started in July, 1990, finished in May, 1991, and comprised a 6,600-ft. ramp and underground drivage, in excess of 8,500-ft. diamond drilling and completed at an overall cost of $6 million. The current year’s emphasis is now being directed toward the feasibility study which will be completed in mid-1993.

In Central Newfoundland, where BP Canada (TSE), Hope Brook’s parent, holds the rights to a continuous block of 530,000 hectares, a number of base metal and gold prospects will continue to be investigated this year. One of these, the “Clementine,” has so far indicated a reserve of 400,000 tons at a grade of 4.8% zinc, 0.3% copper, 2.6% lead, 0.03 oz. silver and 0.012 oz. gold. This property is in the same area as the Buchans mine, closed in 1984. The Buchans mine itself is part of BP’s holdings.