Teck, Western Copper discover high-grade silver in Mexico

A potential silver mine has been discovered at the El Salvador project in Mexico’s Zacatecas state.

A single, vertical diamond drill hole intersected a near-surface 32.6 metres averaging 230.2 grams silver per tonne, starting at a depth of 3.1 metres. The interval, which is believed to represent true thickness, includes 15.9 metres averaging 331.3 grams, beginning at the top.

The El Salvador project is a 55-45 joint venture between Teck (TEK-T) and Western Copper Holdings (WTC-T). Teck is the operator.

The silver discovery occurs 5 km northeast of the San Nicolas massive sulphide deposit in an area where jasperoids, anomalous in silver, lead and barium, outcrop discontinuously over a distance of 1,000 metres.

Drilling will attempt to determine the extent of the high-grade silver mineralization.

In the meantime, preliminary geotechnical studies on the San Nicolas deposit suggest the rock characteristics are favorable to support a preliminary open-pit slope of greater than 50, compared with the 41 overall pit slope assumed in initial scoping studies. This has the effect of reducing the life-of-mine stripping ratio to less than 5-to-1 from 7.8-to-1, thereby decreasing the amount of overburden and waste to be removed by more than 200 million tonnes.

San Nicolas is host to a preliminary open-pit resource of 72 million minable tonnes grading 1.35% copper and 2.27% zinc, plus 30 grams silver and 0.53 gram gold per tonne. Teck prepared the estimate based on the results of the first 34 drill holes. Sixty-one holes have been drilled to date.

The reserve estimate includes a zone of higher-grade zinc mineralization, which sits atop the main deposit. The upper zinc zone contains 19 million tonnes grading 6.15% zinc, 0.79% copper, 1.32 grams gold and 73 grams silver. The deposit lies beneath 160 metres of volcanics and conglomerates. The pre-stripping of 100 million tonnes of waste will be required.

The San Nicolas deposit occurs in the western portion of the El Salvador project, on ground optioned from Luismin, a Mexican mining company. Luismin is carried through completion of a feasibility study, at which point it has the option of participating at 25% by arranging its share of production financing, or it can dilute to a 15% interest.

Teck plans to spend almost US$1 million advancing the joint venture during the fourth quarter. Work will include further metallurgical tests, geotechnical slope design, groundwater evaluation, engineering, ground geophysics, diamond drilling and land acquisition. Western Copper’s share of these expenditures will be funded out of a credit facility available from Teck.