Sydney, Dec 10, 2007 (ABN Newswire) - Discovery Metals Limited (ASX: DML) (AIM: DME) announces a further 46% increase in the Total Inferred Resource within the Company's 100% owned Maun Copper Project in North-West Botswana.
The latest increase follows the definition of an Inferred Mineral Resource of 14.5Mt @ 1.3% Cu and 12.6 g/t Ag, at a cut-off of 0.6% Cu, at the Plutus Prospect within the Maun Project. It means that during 2007, the total Inferred Mineral Resources for the Maun Project have now been increased by 130% (from an initial 20 Mt @ 1.2% Cu).
Discovery Metals' Managing Director, Mr Jeremy Read, said today that ongoing drilling on the Maun Project was proving to be very successful with three Inferred Mineral Resources defined from five prospects drilled during 2007.
"Drilling is yielding a high conversion rate of prospects drilled to Inferred Mineral Resources status which is highly encouraging," Mr Read said. " Plutus is a shallow deposit and we would expect that a significant portion of the identified resource could be mined in an open pit," he said. "The Zeta prospect pre-feasibility study is now well underway, our regional exploration program is being ramped up and with the significant growth in our resource base we are looking forward to an exciting 2008," Mr Read said.
Plutus Prospect Inferred Mineral Resource
Discovery retained the services of Snowden Mining Industry Consultants ("Snowden") to perform an estimation and report tonnage and grade of the copper-silver mineralisation located at the Plutus Prospect. The Plutus Prospect occurs along strike to the north east of the previously reported Petra Inferred Mineral resource and contains sedimentary exhalative style copper mineralisation.
The resource estimation completed by Snowden utilised the results from 21 diamond drill holes drilled by Discovery Metals Limited and a further seven historical diamond drill holes and one Discovery reverse circulation (RC) drill hole (Figure Two). The collection and validation of the drill hole data was completed by Discovery with Snowden reviewing the quality assurance and quality control (QA/QC) data for the Discovery drilling. Snowden did not view the drill hole logs but did review the assay certificates and QA/QC data for the Discovery drilling. Although there was no QA/QC data for the historical drilling, Snowden observed a close correlation between the Discovery and historical drill hole data sets and therefore considered the historical data to be adequate for defining an inferred mineral resource.
The Discovery drill holes were drilled on sections approximately 500m apart with typically two 70m spaced drill holes per section. Six of the historical diamond holes occur on separate cross sections with a Discovery drill hole.
Snowden produced a 3-dimensional mineralisation interpretation based upon the drill hole intersections. The interpretation defined a planar zone of mineralisation sub-divided into two domains. The footwall domain is defined by the eastern geological contact of the hangingwall siltstones and shales with the footwall sandstones and the western hangingwall boundary defined by a 0.6% Cu cut-off. The second domain consists of mineralisation extending from the 0.6% Cu cut-off boundary to an upper boundary at a 0.1% Cu cut-off. Surface trenching has exposed outcropping mineralisation and therefore the interpretation extends to the surface. The interpretation extends to a depth of 200m. The strike length of the interpreted mineralisation is 7,000m and extends 200m north and south of the last sections of drilling.
Ordinary kriging with top cutting was used to estimate the copper and silver grades into a 100 mN by 10 mE by 10m elevation block model using search and estimation parameters defined from the variography. Short range copper and silver continuity is poor due to the wide spaced nature of the drilling conducted over the area. A dry bulk density of 2.8t/m3 was applied as a constant to report the tonnage.
A mineral resource of 14.5Mt @ 1.3% Cu and 13 g/t Ag, using a block cut-off grade of 0.6% Cu has been reported for the Plutus Prospect and classified as Inferred in accordance with the guidelines of the 2004 JORC code. The grade and tonnage values listed in Table One are an accumulation of blocks above a given cut-off within a portion of the Plutus mineral resource block model defined by criteria based on proximity to drill holes and confidence in estimation continuity.
A second round of drilling is being considered for Plutus in order to test the extension of the mineralisation to the south west and to conduct infill drilling with the goal of improving the classification of Plutus mineral resource to an Indicated category.
Table One - Plutus Inferred Mineral Resource
Cut-Off (%) Cu (%) Tonnes (Mt)
0.0 0.9 22.2
0.2 1.0 19.8
0.6 1.3 14.5
1.0 1.4 11.6
1.2 1.5 7.9
