WTF? You silly man. If you add two intervals you need to average...

WTF? You silly man. If you add two intervals you need to average the grade not add them!

0.5m @ 10.4g/t and 0.5m @ 1.5g/t = 1m @ 5.95g/t

Big difference. Apart from the average grades and very mediocre thickness, the other big problem they've now got (on top of all the other problems) is the massive unpredictability of the grade distribution with very poor grade correlation between the individual stratigraphic units.

That 1.5g/t in the lowest conglomerate unit is a big spanner in the works because it compares very poorly with the (higher) grades of the lowest conglomerate unit in the other trenches where the high grade is supposed to be. They're gonna have major problems predicting the grades.