Monterrico puts number on Henry’s Hill

London-listed Monterrico Metals has received its first independent resource estimate for the Henry’s Hill copper deposit, part of the Rio Blanco project in northern Peru.

The estimate, by Snowden Mining Industry Consultants, puts the resource at 177 million tonnes grading 0.98% copper, based on a 0.7%-copper cutoff grade. Of that, 161 million tonnes fall in the indicated category, and a further 16 million at the same grade are inferred.

The resource includes a higher-grade core with 65 million tonnes running 1.26% copper. About half the resource is relatively enriched secondary copper mineralization, which would mainly be acid-soluble; that part of the deposit could potentially be developed as a solvent extraction-electrowinning operation.

Lower cutoff grades bring the resource into the large porphyry-copper neighbourhood: at a cutoff of 0.5% copper, the resource in all categories is 662 million tonnes grading 0.69% copper, and at a cutoff of 0.3%, it increases to 1.1 billion tonnes running 0.58%.

The calculation is based on a 31-hole database at relatively wide spacings.

Monterrico is waiting for the completion of a prefeasibility study, scheduled for September. The study will use the new resource figure in its economic models.

Rio Blanco is now owned outright by Monterrico, Gitennes Exploration (GIT-V) having disposed of its 25% interest for US$1.5 million in April.