Casino, Williams Creek deposits potential Yukon copper mines

Two extremely different copper deposits in the Yukon stand a good chance of reaching the production stage in the next few years.

Proponents of both the Casino copper-gold-molybdenum deposit and the Williams Creek copper oxide property say they’re encouraged by drilling results to date, and that they think the sites could sustain economic mines. “It could be the backbone of the Yukon for a very long period of time,” geologist Alan Archer said of the Casino.

Both properties are in southern Yukon near the town of Carmacks. Williams Creek, 40 km northwest of Carmacks, is accessible by road. The Casino is further northwest past the end of the government-maintained Freegold mining road from Carmacks.

The Casino deposit is owned by Casino Silver Mines (VSE), which is 38% owned by Teck (TSE). Casino Silver optioned the claims in the autumn of 1991 to Archer Cathro & Associates (1981). Big Creek Resources (VSE) acquired the option in November, 1991.

Casino has been actively explored for placer gold since 1912 and for lead-zinc-silver since the 1930s. But the porphyry deposit wasn’t recognized until 1968.

Reserve estimates have ranged widely from as little as 150 million tons copper to more than one billion tons copper.

Archer, a Big Creek director and partner in Archer Cathro, said the emphasis now is on redrilling a higher grade area that was pinpointed using the old data.

Archer said he believes that when Casino’s high gold content — unusual in a copper porphyry showing — is taken into account, the deposit is economic. “The Casino deposit is higher grade in terms of the combined value of the copper and the gold, than any of the porphyry deposits in British Columbia today,” Archer said in an interview in his Whitehorse office. Archer has recalculated reserves at 417 million tons grading 0.3% copper, 0.01 oz. gold per ton and 0.04% molybdenum. Included is a high-grade core of 71 million tons grading 0.46% copper and 0.014 oz. gold.

At the time of the interview, results were in from eight of the 24 holes being redrilled this summer.

“The first eight holes came back better than I’d hoped and better than I’d expected,” said Archer, adding that if the remaining holes maintain those results, a 4-year payback of capital costs is possible based on copper prices of US$1 per lb.

If an open pit mine does go ahead, Archer said the minimum production rate would be 40,000 tons per day. The mine life would be at least 30 years. Under the Casino’s complex option agreement, Big Creek must spend $2 million in 1992 and $1.5 million in 1993 to earn the right to sell the property before June, 1995, provided the sale price exceeds $15 million. At Williams Creek, where Western Copper Holdings (VSE) has acquired the option from Archer Cathro, the drilling season has been busy, with crews ranging from 10-to-20 people.

“We’re drilling some of the other zones as well as the strike extent of the main zone,” said Western Copper president, Bob Quartermain, from Vancouver. “We hope to be in production by 1994 based on a positive feasibility study,” he said, adding that this will be done in the next year.

Current open pit reserves are estimated at 11 million tons of 1.08% copper, based on 55 drill holes.

Thermal Exploration (ASE) is also involved. It spent the first $640,000 in risk capital; Western Copper was working to complete its share — $960,000 — by the end of August. At that point, with $1.7 million spent during four years, the plan called for Williams Creek to become a joint venture of the two companies.

Mining would be done by open pit, with crushing and heap leaching facilities on site and the copper cathode end-product moved by truck to the Port of Skagway, Alaska.