Redbank Mines Ltd (ASX: RBM) today detailed final assays from an infill drilling programme on the Redbank oxide copper project for a definitive feasibility study.

The project area is in the McArthur River Basin - the region where a massive base metals project is being advanced by Xstrata plc - and Redbank's tenements are 40 kilometres from the Queensland border and 50 km from the Gulf of Carpentaria.

The company said final laboratory results from the first 23 RC (Reverse Circulation) of the 29-hole RC and diamond drill programme returned exceptional copper intercepts including:

  • ­37m @ 8.4% Cu from 5m, including 10m @ 20.67% copper; and 35m @ 3.92% Cu from 6m, including 8m @ 12.8% Cu from the Redbank deposit.
  • 12m @ 4.42% Cu from 3m; and 13m @ 4.09% Cu from 8m, including 3m @ 9.55% Cu from the related Azurite deposit.

Redbank's managing director, Gino Vitale, said the final assay results dramatically exceeded preliminary results from a field portable XRF machine, which were reported to the Australian Securities Exchange in early April.

These final laboratory results are significantly higher than was anticipated after our initial field analysis, and enhance the Redbank copper project's overall resource potential and confidence level in our resource base, Vitale said.

Grades received from the nearby Azurite Deposit were also highly encouraging, and Vitale said they were again consistently higher than the average grade calculated for the existing Inferred Resource.

With the Azurite oxide mineralisation less than 3km from the Redbank Plant, these latest assay results provide further strong indication that this deposit will provide an easily accessible ore source for the proposed expansion of the oxide leach operations, Vitale commented.

A Pre-feasibility Study completed in 2007 outlined an overall production profile from mining in the top 100m from surface alone of 31,500t of copper over 5 years, with average copper production of 6,300t per annum.

Last year Redbank announced an upgraded resource within four oxide deposits and three sulphide deposits to 5.03 Mt @ 1.4% Cu for 71,000t of contained copper metal, comprising 1.65 Mt @ 1.7% Cu in the indicated resource category and 3.38 Mt @ 1.3% Cu in the inferred category.

The company said results from six diamond holes completed in April are expected to be announced within the next week.  Vitale said that upon receipt of the remaining assay results, consultants will prepare a revised mineral resource estimate for the project.

Redbank acquired the project in 2005 and has since moved quickly to prove up its resource potential. The company has secured a life-of-mine off-take agreement with international commodities group, Swiss-based Glencore.