AND THERE’S STILL MORE

The 04 break (in underground Tnomenclature) or Kirkland Lake Main break (as it’s more widely known) has been the source of gold ore for Macassa for the past 57 years. It is the same break that nurtured the Lakeshore and Wright-Hargreaves, among others, for so many years. Localized splitting and recombining of major breaks abound throughout the mine, giving an overall braided network appearance on plan. The break occurs within the Timiskaming units that form a belt of moderately south-dipping sediments and volcanics.

The Main break is a thrust or reverse fault with displacement some 1,500 ft. (450 metres) on the overlying sediments. The strike averages N 50^o (deg) east and dips 75^o (deg) south. Several major faults exhibit post-ore movement.

Recently, Macassa’s geology department discovered a narrow but rich structure about 1,300 ft. (390 metres) to the north of the O4 break. This parallel structure has been called the O5 break. “This is not just a little localized thing; it’s got a structure to it,” chief area geologist George Nemcsok told The Northern Miner Magazine.

Macassa has drifted on the 05 break and will soon begin mining it. To the end of 1989, diamond drilling has shown the zone has a combined proven and probable reserve of 70,000 tons at a grade of 0.44 oz. gold per ton (64,000 tonnes grading 15 grams per tonne). This represents almost half a year of production at Macassa. In 1989, drift development on the 6150-ft level contributed some 1,000 oz. of gold to Macassa’s total production. Grades are generally near the 0.5-oz.-per-ton range across up to 6 ft. (17.1 grams per tonne across up to 1.8 metres) Nemcsok and mine geologist Terry Lackey have proposed a series of widely spaced holes to test the easterly extension of the 05 break. The 05 zone has never been tested over the 8,000-ft. strike length of the property and from the 4,500-ft. to the 7,050-ft. levels.

Another fairly recent discovery — hangingwall veins in the 04 break — will yield a good many ounces of gold this year. “We’re dealing with pretty well one-ounce material,” Nemcsok said.