Hi Tau!
I do not think the average grade of the intercepts is the number you should look at. As more data from the vein geometry and grade comes to light, a consulting firm will be hired to crunch the numbers and build a resource estimate. They will probably use a block model for that calculation, in which they take each interval and assume an average grade for every chunk that extends about 20-50m in radius around the known data point. Any chunks that do not have an average above the cutoff value will be ignored and will not count in the total resource. As well, vein intervals that are very narrow and just low grade will also be ignored. Then the ounces estimated in each distinct chunk or block are added up and there is your resource.
So some of the numbers in the NR will not be included and thus their average will not be important. A weighted average of the intervals is going to matter. If you have one meter grading 1 oz per tonne, and 2m grading half an ounce per tonne, the average may be about .75 g/t but it is the weighted average that will be more important, coming in at about .66 g/t. Just adding up all the numbers is not correct, you have to factor in the width of each interval too to get the weighted average.
cheers!
mike