plough that's a good question. The GC drilling should be treated as more of a confirmatory process, as in confirming the existence and continuity of your grade within each mining block, and providing a clear demarcation between what is ore and what is waste.
The pre-mining Resource Definition drilling should pretty much nail the main structures, and the orientation and continuity of your mineralisation. The resultant block model that gets passed to the mining guys (Geo's and Engineers) should be the best estimate possible of where they actually need to mine. Note that I use the word "estimate" here. However, your Res Definition drilling on its own is never close-spaced enough to discriminate between ore and waste in a practical mining sense.
As mining progresses bench by bench, you can feed new Grade Control data into the block model and modify it accordingly. Small changes will be expected and are normal, however, assuming your drillhole spacing is appropriate for the circumstances, you really don't want your GC drilling throwing up any major surprises or unpleasant shocks.
By major surprises, I mean radical and persistent variations in the orientation and grade of your mineralisation that are potential show-stoppers. In this kind of "oh dear" situation, it can sometimes point to a serious problem at the heart of your block model. You don't want to find out that that 7500 t ore block you've just GC drilled that the block model predicts is running at 1.2g/t, is actually running at 0.45g/t.
Remember, your pit shape and costings are all derived from that block model, and if during mining it is found to be significantly underperforming, this can destroy the project economics.
AAM Price at posting:
2.6¢ Sentiment: None Disclosure: Not Held
