2010-12-17_REVISION - C1981019 (130)

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8 A less preferred alternative would be to increase the density of drilling in the zone of expected burnt coal. An RC dg could be used with sampling of drill cuttings taking place where burning is observed or expected. This would be supplemented with an a -log survey. This sampling will involve collection of drill cutting samples at suitable intervals, with sample analysis for a basic suite of properties to confirm the area of coal affected by burning. 2.3.7 Resource and Reserve Definition . An important outcome of the Collom Pre - Feasibility Study resource assessment will be the estimation of Resources and Reserves in accordance with JORC and requirements of the recently introduced Rio Tinto Resource and Reserve Standards. As a result of this review TS has identified the need for CCC to improve the basis for Resource and Reserve definitions and ensure that future estimates are appropriate. Current practice at Colowyo is to use each sample site in isolation. This can result in 'cookie cutter' or 'bulls eye' rings of Measured, Indicated and Inferred Resources. Additionally, Resource confidence currently appears to be classed on a mechanistic basis using US Geological Survey guidelines for drill hole spacing as follows; - Inferred 2,000 m Indicated 1,000 m - Measured 500 in The required number of samples is not currently defined. Although it is a matter for the KEC Competent Person to determine the basis for Resource classification, it should be noted that the current approach is inconsistent with the intent and interpretation of JORC as applied elsewhere in Rio Tinto. 2.4 Mine Planning Preliminary mine planning for Collom has been completed using data available prior to the current exploration program, which is the same as that used in the 2003 CRS. An ultimate pit RIO TINTO TS Ref: DRAFT Version: 1 Figure 2 -3: Magnetic Survey Diagnosis of Burnt Coal Zones