Open pit Potential seen for Yukon gold prospect

A major exploration program financed by Chevron Minerals has outlined significant gold mineralization on a property in the Yukon held under option from Vancouver-based B.Y.G. Natural Resources.

What is really intriguing about the project is its open pit potential — something that was largely overlooked in the past.

Chevron spent $1 million last year on the Mt. Nansen project, located at the bottom end of the Dawson range some 110 miles north of Whitehorse. Incidentally, that was double the company’s work commitment and its budget this season will be close to that figure again, says B.Y.G. President Thornton J. Donaldson.

The option agreement with Chevron probably best reflects that company’s interest in the property. By spending $6 million over a 5-year period, Chevron can earn a 62% participating interest, but only after spending that amount will it have any equity in the project. This would make it very easy for B.Y.G. to take on another partner in the event Chevron dropped out.

Prior to the 1985 program ore reserves were calculated at 184,538 tons grading 0.42 oz gold and 11.7 oz silver in the proven and probable categories. Less than one- quarter of that was attributed to the Brown-McDade zone which was drilled and trenched extensively last year.

Mr Donaldson sees a dramatic expansion of Brown-McDade reserves based on an independent analysis of Chevron’s work by B.Y.G. officials. There now are thought to be more than 800,000 tonnes in that zone grading 0.23 oz gold and 2 oz silver, most of it probably open pitable.

The Brown-McDade is quite complex and consists of three different mineralized zones spread over a width of 500 ft. The reserves occur in the footwall of a major fault and the average width of the main zone is about 35 ft, he notes.

The property comprises some 20,000 acres and includes a number of significant gold deposits, many of which were worked on a small-scale basis in the past. The Huestis zone was last mined in 1975 when 6,429 tons were processed grading 0.3 oz gold and 7 oz silver.

A 300-ton-per-day mill exists on the property which has been vandalized to some extent but could be reactivated and the throughput increased for approximately $1 million, he points out. Grade control was a big problem in the past and the plant didn’t have a cyanide circuit, so recoveries were poor.

Three distinct types of mineral deposits have been recognized at Mt. Nansen. Narrow, rich precious metal veins have been found in the Huestis and Webber zones and complex but wider zones in the Brown-McDade. Disseminated and stockwork copper mineralization have also been outlined on one area of the property from the days when porphyry copper exploration was the only game in town.

Chevron discovered another zone this year called the Flex (N.M., Sept 15/86) which consists of two sets of sub-parallel veins. The zone is much wider than the Huestis and Webber and has good open pit potential. The Flex is oxidized (like the Brown-McDade) and the tonnage potential is also comparable, he says.

Chevron spent a large part of this year’s exploration budget on the Flex zone and more results are expected shortly. None of the deposits have been closed off although some have been offset by faulting.

Gold is associated with pyrite and arsenopyrite in the Huestis zone but is free in oxide zones and probably easily recoverable. These are epithermal deposits and the property has not been glaciated so erosion has been minimal, suggesting tonnages could be substantial. Existing reserves are contained on 4-5 claims and Mr Donaldson confirms the ore-to-vein ratio is very high and ranges from 50%-75%.

Road access is from Carmacks, 37 miles to the east and a 4,000-ft airstrip is situated on the property which requires minor repairs. Archer Cathro and Associates, consulting geological engineers, who are probably more knowledgeable about Yukon geology than any other consulting group, are managing the program for Chevron.