Grade up at Dolores

Vancouver — Re-analysis of low-to-mid-grade core samples from the Dolores project in Mexico has increased silver values by 36.3% for owner Minefinders (MFL-T).

The improvements are based on “total digestion” analysis of samples taken from mineralized drill intercepts, whereas, previously, “aqua-regia digestion” analysis was performed. Some intervals containing abundant silver-halide minerals increased in grade by more than 100%. Hole 114 saw its silver grade jump a whopping 132% to 102.1 grams per tonne over 16.2 metres at a down-hole depth of 156 metres.

The junior re-analyzed 560 oxide samples resulting in a jump of 61.2% to 41.7 grams silver, from the previously reported 25.9 grams. Some 492 re-analyzed samples of mixed oxide-sulphide material resulted in a 22.4% jump in silver values to 35.3 grams, from the previously posted 28.8 grams. The re-assay of 277 sulphide samples showed a 12.9% increase in silver grades to 28.6 grams, from 25.3 grams.

The revised assays result in a higher overall grade for the deposit, and a consequent increase in the total resource. Minefinders hopes this will translate into higher production, better stripping ratios, lower production costs and greater cash flow.

Situated in Chihuahua state, the Dolores gold-silver project is Minefinders’ chief asset. An updated model of the Dolores open pit, based on gold and silver prices of US$300 and US$5 per oz., respectively, points to a resource of 67.2 million tonnes grading 0.96 gram gold and 53.6 grams silver per tonne. The stripping ratio is projected to be 4.2-to-1.

The higher-grade mineralization consists of 23.4 million tonnes at 2.09 grams gold and 124.5 grams silver per tonne, and Minefinders intends to process this material (which represents 35% of the open-pit resource) in a mill grinding circuit. The residual pulp would then be agglomerated with lower-grade material for standard heap-leach processing. Metallurgical tests project overall recoveries of 86-89% for gold and 57-65% for silver.

The mine life is pegged at 13 years, during which time annual production would average 138,359 oz. gold and 6.3 million oz. silver, or 242,900 oz. gold-equivalent, at an estimated cash cost of US$149 per oz. and a total cost of US$184 per oz. gold-equivalent. Capital costs are pegged at US$77 million.