Atna eyes Chanarcillo silver stake

Vancouver-based Atna Resources (ATN-T) has granted Apex Silver Mines (SIL-X) an option to earn a 70% interest in the Chanarcillo silver property in the historic mining district of the same name in northern Chile, 70 km south of Copiapo.

Apex can earn its stake by paying Atna US$150,000 in cash and sinking US$1.3 million into exploration over the next 3 years.

Atna will remain as project manager until Apex earns its stake. Once vested, Apex will carry Atna’s 30% share of expenditures plus US$50,000 annually until a feasibility study is completed and a production decision is made. After that, Atna will have 60 days to reimburse Apex for its post-production share of funding and to assume its share of the ongoing financing.

The two plan a 3,000-metre drill program later this month. Most of the holes will target the 400-by-700-metre Hilltop Breccia, a collapse-structure in the carbonate host rocks. Surface geochemical sampling there returned silver values up to 210 grams per tonne. The partners note that this is significant, as extensive leaching has removed most silver from the surface in the district.

Several other holes will test for high-grade veins or vein stockwork zones and massive sulphide replacement deposits. Others will test geophysical anomalies and structural targets elsewhere on the property.

The property lies at an elevation of 1,100 metres, 14 km off the Pan American highway. Historic production dates back to between 1865 and 1915, when more than 100 million oz. silver were mined from oxidized veins, chimneys and mantos above the water table. Atna says the historically complex land ownership has restricted modern exploration.

Several stratabound zinc-rich massive sulphide manto bodies occur at various depths in the old workings. These sulphide bodies were never mined, owing to lack of oxidation and the associated difficulties of extracting the silver from sulphide minerals. Atna believes the Chanarcillo district represents a potential carbonate replacement target.