Here's some commentary on yesterday's NR:
Mining.com - Pretivm up on a down day. Where we read:
Pretium Resources (TSE:PVG) announced more high grade gold intersections at its Valley of the Kings, which pushed the stock 5.73% higher to $6.12.
Sucks to not be long PVG, I guess. So what are these great results?
Hole VU-365 intersected 328.91 grams of gold per tonne uncut over 20.50 meters, including 13,400 grams of gold per tonne uncut over 0.50 meters;
Now, I seem to subconsciously do grade subinterval calculations in my head, because this rang an alarm bell. So I went off to the corebox drill interval calculator and plugged these numbers in and got:
20.5m @ 328.91g/t minus 0.50m at 13400g/t = a residual of 20.00m @ 2.133g/t
and that residual is waste, which makes me ask why the hell they report it. Why not just report the short high-grade interval?
Hole VU-369 intersected 96.71 grams of gold per tonne uncut over 44.95 meters, including 7,700 grams of gold per tonne uncut over 0.50 meters;
The residual here is 44.45m @ 11.18g/t which is better. Though having took first-year physics I ask whether that 0.50m high-grade interval is exactly 0.50m, or if they simply round off as a matter of custom.
After all, if the process rounds everything off to the nearest half-metre, then a 0.545m interval at 7700g/t means a residual of 44.405m @ 3.392g/t, and again the residual is waste.
Hole VU-384 intersected 331.99 grams of gold per tonne uncut over 8.00 meters, including 5,210 grams of gold per tonne uncut over 0.50 meters;
Which means a residual grade of 7.5m @ 6.789g/t. Again, assuming exactly 0.5m, and assuming exact numbers instead of carrying through error.
Speaking of which, do P.Geos go to university? If so, do they take first-year physics? At all? Are they required to pass it? Cos when I went to U, we had it beaten into our skulls that no number can ever be reported unless you include the complete margin of error. Seriously. That was the only reason we did those stupid 3-hour labs every week: to learn that there's no such thing as exact measurement of anything, and indeed that reporting numbers as if they were exact is unethical and/or incompetent.
So in every situation, you have to calculate error, and report the maximum and minimum possible values.
I mean, simply splitting a core, mashing, and pulling a sample should introduce error. Why do these numbers come without error estimations? Any professional geologists want to explain why their profession gets a pass from the proper and conscientious reporting of data? Error seems to be a major caveat in high-grade narrow-vein data.
Hole VU-390 intersected 179.14 grams of gold per tonne uncut over 13.50 meters, including 4,780 grams of gold per tonne uncut over 0.50 meters;
Which means a residual of 2.184g/t over 13.5m. I.e. waste.
Are these larger intervals (8m, 13.5m, 20.5m, 44.95m) being reported simply because that is the minimum size of tunnel or vault that will need to be constructed to mine the vein at that location?
Because hey, if you're trying to tell me that mining that 4780g/t interval will require constructing a 3m wide by 4.5m high tunnel to follow that vein, then I understand: you're saying the total bulk around that vein will still come in at 179g/t, so it'll be profitable.
But this is supposed to be an open pit, no?
Anyway, if the P.Geo associations, or maybe the BCSC and OSC, would like to initiate a process of refining the NI 43-101 to force companies to include error calculations in drill results, that would be very nice of them. Because it's first-year science. And it would mean less misleading data. This is a perfect example.