Gold an exception to declining reserve trend

Compared with 1981, Canada’s reserves of copper, nickel, zinc and silver in 1991 were down by about one-third. They dropped by almost 40% for lead and were off by 65% for molybdenum. Although reserves of gold have decreased in each of the past two years, as of early-1991 their level was still more than double that of 1981.

Some 1,548 tonnes of gold were contained in reserves of proven and probable minable ore in 1991, down by more than 6% when compared with revised estimates for 1990. New mines committed to production during 1991 added almost 50 tonnes to reserves.

Several mines reduced their gold reserves by more than the amount mined during 1990, among them Campbell, where there are now some 1.2 million fewer ounces than a year earlier.

In 1991, reserves of silver stood at 23,227 tonnes, down by almost 12% from the previous year. The most noteworthy addition resulted from the inclusion of Sa Dena Hes totals.

Among the operations with the largest decreases in silver reserves were Caribou, where a $65 million writedown and

closure were announced; Brunswick, where proven ore is now reported as minable rather than as mineral inventory; Samatosum, where grade was reduced and the presence of a fault disrupts the continuity of the ore zone; and Premier, where the owner dropped more than 2 million tonnes of ore. There were two outstanding sources of gross additions to zinc reserves during 1990, Sa Dena Hes and Heath Steele-Stratmat. In contrast, there were a number of significant reductions to zinc reserves, the largest at the Brunswick No. 12 mine. Overall, reserves of zinc declined to 20.1 million tonnes in 1991, down by over 4% compared with 1990.

Lead reserves fell to 6.3 million tonnes in January, 1991, a decrease of more than 6% from the previous year. The largest addition resulted from the first-time inclusion of Sa Dena Hes and the largest gross decreases from apparently unreplaced production at Faro, from the closure of Caribou and from a change in reporting proven ore at Brunswick.

There were some 5.8 million tonnes of nickel in mine reserves in January, 1991, down by about 6% compared with 1990. An amount of nickel, equivalent to about half of what was mined during 1990, was apparently no longer counted in mine totals at the beginning of 1991. Inco’s aggregate reserves of nickel decreased by about 5%.

Between 1990 to 1991, only a few mines appear to have maintained or added to their nickel reserves. Reserves at Langmuir No. 1 were included in Canadian totals for the first time in 1991, but they are small.

In January 1991, reserves of copper amounted to 11.2 million tonnes, down from 12.2 million tonnes a year earlier. There were fewer than a dozen mining operations with apparent additions to their copper reserves during 1990. Only one operation, Goldstream, which was reactivated in 1991, stood out. In addition to decreases caused by production, significant reductions in copper reserves occurred at Highland Valley, Inco and Kidd Creek. Taking all operations into account, reserves at the beginning of 1991 were some 8.5% lower than in early-1990.

Canadian reserves of molybdenum amounted to 193,000 tonnes in early-1991, or about 10% less than in early-1990. Only one of the five mines in Canada that produced molybdenum appears to have replaced a portion of the molybdenum extracted from reserves during 1990.

Andre Lemieux is Mineral Economist with the Mineral Policy Sector of Energy, Mines and Resources Canada.