This re-evaluation of Zeta follows infill drilling of the resource to approximately 150 metre sections and confirms a new mineralisation interpretation for Zeta which is consistent with the recently published Plutus interpretation (6 October 2008). This new interpretation uses slightly lower densities.
Improved testwork has reduced the range of densities adopted from between 2.84 and 2.87 down to between 2.64 and 2.70. The previously evaluated mineralised zone at Zeta has now been split into;
- A higher grade zone, which contain approximately 80% of the volume but slightly more metal than the previously evaluated mineralized zone. As a result the grade of the resource is now 22% higher in copper grade (1.2% to 1.5% Cu) and 10% higher in silver grade (18.2% g/t to 20.1 g/t Ag), and
- A zone which is 20% of the volume of the previously evaluated mineralised zone, containing lower grade mineralisation and which is now being classified as below the Resource cut off grade.
This is a positive outcome resulting from improved understanding of the distribution of grade across the mineralised zone.
The Mineral Resource at the Zeta prospect is now 25.2Mt @ 1.5% copper (Cu) and 20.1 g/t silver (Ag) at a cut-off grade of 0.6% Cu (Figure 2) and comprising:-
- Zeta Indicated Mineral Resource 3.9Mt @ 1.7% Cu and 26.1 g/t Ag, and
- Zeta Inferred Mineral Resource 21.3Mt @ 1.4% Cu and 19.4 g/t Ag.
The new Zeta Mineral Resource delivers approximately the same tonnage of contained copper but at a 22% increase in copper grade and a 10% increase in silver grade.
----------------------------------------------------------- M/t Cu Ag Cont. Cont. Grade Grade Copper Silver (% Cu) (g/t Ag) kt Moz ----------------------------------------------------------- July 08 Zeta Resource 30.0 1.2 18.2 360 17.6 December 08 Zeta Resource 25.2 1.5 20.1 378 16.3 (Decrease)/Increase (16%) 22% 10% 5% (7%) -----------------------------------------------------------
Included within this new Zeta resource is a high grade zone which is separately domained and modelled. This high grade horizontally plunging zone contains 2.2Mt @ 2.5 %Cu and 38.2 g/t Ag and is some 1,500 metres long and is interpreted within 25 metres of surface.
In addition an extensive low grade zone of 5.4 Mt @ 0.3% Cu has been confirmed in the hanging wall (similar to the 7.9 Mt @ 0.4% Cu at Plutus). These Plutus and Zeta low grade zones have not been included in the Mineral Resources at this time as they occur below the 0.6% Cu cut-off. This material, located within the hanging wall of the reported Mineral Resource, is currently considered subeconomic and classified as waste.
Implications for Boseto:
The 22% increase in copper grade of the Zeta Mineral Resource follows on from the recent 23% increase in the copper grade of the Plutus Mineral Resource.
Discovery Metals’ Managing Director, Brad Sampson said "A reinterpretation and remodelling of the Zeta resource was required following the drill out of the prospect over the past six months. The remodelling also needed to be consistent with the methodology used for the recently upgraded Plutus resource."
"This new resource estimate is significant for the Boseto economics because it shows that
- we have more contained copper in mineral resources at Zeta than previously modelled, with an increase of 5.0%, and
- the metal is contained within 16% less tonnes of mineral resource."
"This means that Zeta should be able to be mined and processed at significantly higher grade than we had previously estimated. At a planned milling rate of 2Mtpa, the grade increases of 22% at Zeta and 23% at Plutus mean that the project should be capable of producing an extra 5,000 tonnes of copper in concentrate each year for a potential annual output of 28,500 tonnes compared to 23,500 tonnes as per the PFS."
"In addition, confirmation of a high grade zone at Zeta with grade of 2.5% Cu presents a significant opportunity for early stage mining of copper grades well in excess of the average grade of the resource. We now have identified a number of these high grade zones at Plutus and Zeta which could become high grade starter pits with the potential to reduce cash operating costs in the early years and enhance project cash flows and economics."
"We will be developing new mining schedules as part of our ongoing BFS work, but as we are expecting new resources from Petra and the Petra-Plutus gap, this will not be completed until this new information is available. At this stage we expect to be able to provide a more comprehensive update on the new schedules and project economics in Q1/09."
The Boseto Copper Project Mineral Resource following this re-evaluation, reported in accordance with The Australasian Code for Reporting of Exploration Results, Mineral Resources and Ore Reserves (The JORC Code, "2004 Edition") is;
45.6Mt @1.5%Cu and 18.7g/t Ag containing approximately 684,000 tonnes copper metal and 27 million ounces silver.
The previous resource estimate was
50.4Mt @ 1.3%Cu and 17.6g/t Ag containing approximately 655,000 tonnes copper metal and 26 million ounces silver.
Future Resource Upgrades:
Mineral Resource modelling work is currently underway for the mineralised zone located between the Plutus and Petra prospects. Current assessment suggests that the mineralisation may be continuous and that an Inferred Resource may result from the evaluation. The strike length of this zone is approximately 1,500 metres.
Further Mineral Resource modelling is also occurring to develop a model for the silver mineralisation present at the Petra Prospect. An improved Petra Mineral Resource is expected when this work is completed in early 2009.
In addition to these evaluations, Discovery has recently extended the strike length of the Petra prospect with a new zone of copper anomalism in soils extending its strike length by more than 200% (an extra 3,600 metres). These results were announced recently and will result in this prospect extension being drilled in the near future.
All the Boseto copper prospects are open at depth and may be amenable to extraction through future underground mining operations. Further work on the underground potential of the prospects will be completed as part of the bankable feasibility study process.
Boseto Project Background:
Discovery Metals' Boseto Copper Project (100% owned) is located in north west Botswana, within the district of Ngamiland, approximately 80km south-west of the town of Maun. A seven tenement package was granted to Discovery Metals in September 2005 and fieldwork on this tenement package commenced late in October 2005. The Government of Botswana approved the Company's re-application for these tenements in September 2008 and all prospective areas were retained by the Company. The outer limit of the exploration licence area starts approximately 60km south west of Maun and stretches in a south westerly direction for approximately 200km towards the town of Ghanzi. In June 2008, Discovery Metals was granted an additional seven tenements extending from the south west boundary of the original 2005 granted tenements through to the Namibian border, adding 5,700km2 to the area held under prospecting licenses to bring the total current tenement area to 10,100 km2.
The Boseto Copper Project is located within a belt of significant copper-silver mineralisation that extends from the well known and more highly developed Zambian Copper Belt across north west Botswana and into Namibia. The poorly explored and undeveloped portion of this belt in north west Botswana is known as the Kalahari Copper Belt.
Copper occurs predominantly in chalcocite, with minor amounts of bornite and other copper sulphides present. At shallow depths, malachite and chrysocolla exist in significant proportions within some areas of the mineral resource.
A Pre Feasibility Study for the Boseto Copper Project was completed on time and on budget in July 2008. Discovery Metals is currently undertaking a Bankable Feasibility Study for the Boseto Copper Project.
About Discovery Metals Limited
The goal of Discovery Nickel is to create shareholder wealth through the discovery and development, of economic deposits of nickel-copper sulphide resources. The company strategies are to focus on the discovery and development of high grade, high margin nickel sulphide ore deposits.
Discovery Metals Limited