RE: 3 things that I wonder about...While I am not properly qualified to comment, that does not seem to be a deterrent to other posters, so here goes:
1. You are correct in the sense that high grade gets boosted by a non-cut-off. In some situations this 'nugget-effect' distorts the average, but in others (like ours) it can be proper in the sense that it is encountered frequently and can be expected to be representative. As for the low grade, you do not get it both ways. If the cut-off is applied, then the zone is presumed barren, while some economic ore may nevertheless be present. The bottom line is that the average does not get reduced, but the interval is shortened.
2. We have seen this before. They assay the good-looking stuff first, then come back for the rest. Nothing wrong with that
Previously we have seen an expanded mineralisation after further assay.
3. Accept what they say at face value. The geology is complex. Better to say you do not know, rather than raise false expectations
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