native copper page 9 of jorc report, page-12

It isn't very clear, but what they have performed is a version of a fire sceen assay (but for copper rather than gold). This "picking out" of the plus 2 mm copper grains has not compromised the assay, but it appears that the plus 3 mm copper nuggets have not been included in the assay. So, the assays relate only to the fine grained native copper (minus 3 mm). But we know there are cores of almost pure copper. To put it another way, most (probably 95% plus) of the native copper is not included in the assays.