somewhere in the RC drilling and sampling the lower gold grade...

somewhere in the RC drilling and sampling the lower gold grade bias of the RC means there is gold loss somewhere between that drill bit hitting the bottom of the hole and the 50g assay charge ( excluding assay bias) - the whole point of RC over the years has been to minimise dilution and smearing between samples and contamination from up the hole by having hammers that have holes in the face of the bit to take the chips directly from the face up the inner tube of the RC rods, the next challenge is to split the chips evenly so no bias occurs so one imagines u should not lose too much gold at the hammer face - so it may well be not a loss of gold there, but a possible systematic sampling error at each and every the splitting stage of the entire 1m sample of chips