PERTH (miningweekly.com) – Dual-listed gold miner Perseus Mining has reported a maiden underground ore reserve of 2.2-million tonnes, grading 3.59 g/t gold for 259 000 oz of gold at the Yaouré gold mine, in Côte d’Ivoire.

A prefeasibility study (PFS) on the drilled-out portion of the CMA deposit at Yaouré has been completed which has proven the economic and technical viability of underground mining immediately beneath the existing openpit, adding additional value to the Yaouré gold mine, the company told shareholders.

Perseus is currently mining the CMA orebody at the Yaouré gold mine using conventional openpit mining methods.

“Having attained the goal of producing gold at a rate of 500 000 oz/y across our three gold mines, we are now working to maintain, and where possible, exceed that level of production over the next decade and beyond,” said MD and CEO Jeff Quartermaine on Tuesday.

“These latest drill results from Yaouré give us further confidence in the high-grade gold contained beneath the CMA openpit and the results of a PFS and maiden ore reserve for the first portion of CMA underground project are encouraging. This initial stage of the development will carry the bulk of the development costs of the underground operation, and as further resources and reserves are delineated by the drilling programmes currently underway on the site, the average all-in sustaining costs should be reduced, turning the CMA underground into a very profitable extension of the already profitable openpit operation.

“We look forward to progressing Perseus’ first underground mining development which is also likely to be the first large-scale underground mine operating in Côte d’Ivoire,” he added.

The ASX- and TSX-listed group’s total measured and indicated mineral resources at the end of June stood at an estimated 132.9-million tonnes, at 1.19 g/t gold for just over five-million ounces of gold.

The resource included the CMA underground estimate and the maiden mineral resource and reserve estimate for the Nkosuo project, at the Edikan gold mine, in Ghana, of 10-million tonnes, at 1.04 g/t gold, containing 332 000 oz.

Nkosuo is a substantial addition to the Edikan gold mine, and would extend the mine life by 18 to 24 months to 2027.