The primary distribution of values in the mineralized zones of the Bellechasse-Timmins gold deposit is erratic within the gold-hosting quartz and the distribution of quartz within the fractured diorite tends to be chaotic.
This seems to suggest that these aren't normal veins that you can follow underground. The gold is randomly located within the quartz, and the quartz is randomly located within the diorite. Really suggests that unless your geo really knows this type of deposit, hitting sufficient mineralization to support underground mining will be all down to luck.
So a good test would be underground bulk sampling. If despite all this randomness Tilsley can stick a dart in a 3D map and tell you exactly where to grab an underground bulk sample, and if that bulk sample then returns a decent mineable grade, then GNH becomes a mine (assuming the tonnage is sufficient and the economics look good to a company that would buy them out). Or at least that seems to be Cook's opinion.
a series of cross-sections that suggest a tendency for drilling results to give grade estimators lower than obtained from larger (e.g. bulk) samples.
I never understood this part. I would think that the average density of gold, averaged out over a large enough cross-section, should stay the same no matter what sampling method is used and no matter how chaotic the distribution. That's why I'm looking at the longer intervals and averaging out: we might miss that speck of gold at 155m, but we should have hit others in other locations within the mineralized envelope.
Now if they're only trying to hit small mineralized envelopes of say 5m width, then yes, most of them should turn up barren results on the drill, right? But I truly think such narrow envelopes aren't mineable. You don't open-pit low-grade narrow veins. Open-pit is for massive deposits like what EVG was trying to prove up in Nevada.
And underground mining requires a certain grade. Underground also requires a certain total deposit tonnage to be able to carry the CapEx costs of the mill, adits, etc.
There does appear to be an increase in background values in those locations where 'good' gold values can be expected. Rarely do gold values over 1g/tonne occur in the absence of an 'envelope' or 'background' of ~50 to 150+ ppb Au.
I guess this is meant to suggest that any intervals we have that assay .05-.15 g/t count as the "mineralized envelope" they're shooting for. In that case, any of those .05-.15 intervals can be counted as being places where the drill "just missed" hitting a higher gold concentration. Maybe it's instructive, then, to review the drill holes to see what size these >.05g/t intervals' lengths are?
