New estimate for Rio Blanco (March 28, 2006)

Consultants for Monterrico Metals (MNA-L) have calculated a new resource estimate for the Rio Blanco copper-molybdenum deposit in northern Peru, reflecting another 15,000 metres of drilling on the project.

The resource estimate, by Snowden Mining industry Consultants, puts the size of the measured and indicated resource at Rio Blanco at 816 million tonnes at an average 0.59% copper and 0.023% molybdenum. An additional inferred resource amounts to 441 million tonnes at 0.52% copper and 0.016% molybdenum.

The measured and indicated resource splits out into a supergene zone with 269 million tonnes grading 0.73% copper and 0.014% molybdenum, and a primary sulphide zone with 548 million tonnes grading 0.53% copper and 0.028% molybdenum. In the inferred resource, 90 million tonnes grading 0.57% copper and 0.011% molybdenum are in supergene material, and another 351 million at 0.51% copper and 0.024% molybdenum are in sulphides.

The resource is cut off at 0.4% copper.

Monterrico’s consultants, led by the Chilean office of Hatch, are completing a final feasibility study on Rio Blanco, which is near the Ecuadorean border in Piura region. The current production scenario is for a 25-million-tonne throughput of ore annually, to produce 200,000 tonnes copper and 2,500 tonnes molybdenum metal in separate concentrates. At that rate of production, the measured part of the resource would cover six years of operation; the option of doubling throughput in the third or fourth year of production will be explored in the feasibility study.