Alchemy or Miscalculation, page-3

How did the ROM ore get its grade worked out ?
If it was from an estimate based on block models from krigging wire frames , a reserve for each block calculated and then a dilution factor applied for a sloppy escavator driver it may have been quite inaccurate in determining the ROM ore grade.
Alternatively if the grade was determined by taking bulk samples of ore at the site then that to could be inaccurate as there may have been insufficient sampling .
Is not the fact the ore is over reconciling for grade a good thing anyway so why are you trying to dish the guys holdman?
The overcall may have even been greater as there would have been less than 100% process recovery (unless you had a recovery % in your calculations holdman.
Not a mining pro so just my armchair observation.