Corriente making presence felt in South America

Few juniors active in South America have managed to assemble control of an entire mining district, complete with mine, town site and mill. But such is the case with Corriente Resources (VSE), which owns five large projects in Bolivia, Ecuador and Argentina.

The company’s most advanced project is Tasna, a 6-by-4-km mining district in southwest Bolivia, where previous mining was focused on

bismuth-tin-tungsten-gold vein targets. Corriente plans to reopen the existing mill and produce from these vein-type reserves, but it is also interested in evaluating several bulk-tonnage targets where disseminated gold-copper, stockwork mineralization has been identified.

Tasna includes a mine camp with housing and a school, a 350-ton-per-day flotation-gravity mill, and considerable mining equipment. The only bismuth smelter in South America is situated nearby.

Corriente’s involvement in Tasna grew out of its initial interest in bismuth, a non-toxic metal with properties similar to those of lead. The company believes bismuth will be used increasingly as a substitute for lead in future decades. The metal is currently produced from secondary sources such as the smelting of copper and lead, and the mining and milling of molybdenum and tungsten.

Bismuth prices have been below US$3 per lb. in recent years, largely as a result of oversupply from Chinese sources. Corriente is of the view that prices will rise over the medium term as these stocks are reduced and as bismuth usage increases.

Tasna is reportedly the world’s only primary source of bismuth and has minable reserves, as well as the potential to expand the known resource. A feasibility study, to be carried out this year, will focus on reopening the existing mill and producing from known vein reserves.

“The essentials (mine, mill, etc.) are already in place, so capital costs will be low, at less than $5 million,” said Corriente President Kenneth Shannon. “We have been approached by partners willing to fund this project to production and will look at that option, although we could do it ourselves.” Proven and probable reserves reportedly exceed 700,000 tons of 1.7% bismuth, 0.6% copper, 1.5 grams gold per tonne, 1.18% tungsten and 0.3% tin. The property is also said to contain large tonnages of lower-grade bismuth reserves not yet classified as ore.

Aside from Tasna’s bismuth potential, Corriente views the district as one of the most promising bulk-minable gold-copper targets in Bolivia. A large gold-copper stockwork was previously sampled by the United Nations, which outlined a geological resource of 29 million tons averaging 1.2 grams gold and 22 grams silver plus 0.5% copper. This resource is contained within one of three known bulk-tonnage targets.

The existing workings at Tasna have cut through areas of disseminated gold-copper mineralization. Sampling of these areas will be followed by more detailed work once they have been assessed under the current exploration program.

(Helping the company manage its various South American projects is Charles Melbye, who recently joined the board to share his considerable experience and contacts in South America.)

In Ecuador, Corriente is exploring El Rosario, a project considered prospective for large, gold-silver, bulk-tonnage deposits. A program of mapping, sampling and geophysics is aimed at defining drill targets. The junior also holds 10,000 hectares, covering a large, volcanic caldera on the Bolivian-Argentine border. The land package contains epithermal gold mineralization accompanied by widespread geochemical anomalies, and exploration is aimed at defining disseminated gold deposits minable by open-pit methods.

Also near the Bolivian-Argentine border is the company’s Pabellon project, which is in an area where gold and antimony were mined in the 1930s and 1940s from quartz veins. Exploration will focus on areas considered prospective for widespread gold mineralization.

A past-producing gold-antimony mine exists on Corriente’s Maria Angelica project, 26 km from the Chilean border.

Although past production was focused on narrow, high-grade vein systems, Corriente’s exploration will be focused on bulk-tonnage targets. Field examination of several of these properties has shown extensive wallrock alteration zones containing gold values ranging from 7 to 9 grams gold per tonne.

Corriente has arranged $4.5 million in private placement financings to advance the Tasna project and explore its other South American properties.