Queenstake’s placer mine big business in Atlin

In small communities like Atlin where placer mining is the major industry, a code of honour exists among locals that is rarely broken. Stealing from your employer is taboo and those that do are ostracized and generally never find work again in the industry.

Even so, two RCMP constables were on hand when Queenstake Resources (TSE) cleaned out a sluice box at its Pine Creek operation, one of the largest such mines in British Columbia.

The security was far from intimidating and their well-marked vehicle was probably sufficient enough to discourage any unwanted guests. But gold, even in raw nugget form, often does strange things to men and smart companies don’t take any chances.

To say that placer mining and the people working in the industry are unique is somewhat of an understatement. And so is each alluvial placer deposit including Queenstake’s Pine Creek project just a few miles from Atlin.

For the uninitiated, gold placers are superficial mineral deposits formed by mechanical concentration of weathered particles; mother nature erodes huge volumes of hard rock material over time and concentrates it in stream beds and topographical lows.

The discovery of a placer gold deposit is generally not indicative of a larger, higher grade, hard rock gold deposit nearby. Placer operations move huge volumes of material to recover small amounts of gold and mother nature used the same methodology to deposit it there in the first place. So the concentration ratio is extremely high.

Queenstake’s Pine Creek project is expected to produce about 7,500 oz of gold this year, over half of the company’s total output for 1988. Purchased by Queenstake for $2 million last year, the acquisition included a complete camp, loading and hauling equipment, and two trommel screen sluice box recovery plants, which were operating when The Northern Miner visited the property.

The deposit is a gold-bearing orange-coloured tertiary age gravel channel that is buried by 30-50 ft of glacial overburden. About 600,000 tons of old tailings and in situ reserves will be removed this year, according to Gordon Gutrath, Queenstake’s president.

Placer mining has been a part of the Atlin scene for years Lance Kennedy, mine manager, told The Northern Miner, and he added it was the lifeblood of the community. He pointed out that an 1897 American Nickel was found in the old placer diggings “which just goes to show you that those placer mine rs were all over.”

Mining is seasonal and usually involves a seven-month operating season but stripping can be done after freeze up. Employees work 12-hour shifts, six days per week, and they get a week off mid-season to avoid “burn out,” he stated.

The so called “pay channel” is 600 ft wide but not all of it is gold- bearing and it “doesn’t seem to be an old river channel,” he said. At least three summers of reserves are indicated at present and they expect to move about one million yards of material this season. (It’s really a big earth-moving operation).

Kennedy said they can make money from peripheral areas grading 0.015 oz gold but he noted that grades in the centre of the channel typically average 0.06 to 0.08 oz gold per cubic yard. The company mines to a cutoff grade of 0.006 oz gold. Values near bedrock are typically higher and 3-4 ft of bedrock is removed to ensure all the gold has been recovered.

In this case, the bedrock is soft serpentine and to find the limits of the gold-bearing material they pan some of it; when no “colors” or black sand are present, they are out of the pay zone. Old placer miners were often fooled by “false bedrock,” a decomposed rock that sometimes has pay material underneath it. “When it has boulders, it’s a dead giveaway,” Kennedy insisted.

Reserves covered by heavy overburden are usually drilled and they look for black sand (or magnetite) as a marker. But the best sampling device is the trommel, a perforated cylindrical plate which is used to screen rock before it’s deposited on the sluice.

Queenstake has two trommels at Pine Creek and they would need some additional stripping equipment (a D-10) and haulage trucks to justify installing another one. Maintaining equipment is a major expense at the mine, accounting for about half of total operating costs; labour represents the other half, he said.

Last year Queenstake produced 13,222 oz gold from placer operations in British Columbia and the Yukon, double the previous year’s output. The Pine Creek operation was responsible for the increase and there is considerable reserve potential yet in the region, The Northern Miner was told.