You're right about AISC for a project (not necessarily BLK) not necessarily being economic even if below spot, because as I've always suggested you need to include all the overheads as AISC is project specific, not company specific (once again this is a general comment, not BLK specific).
I also agree that mining companies, especially juniors, make their living off producing optimistic studies because if it doesn't have a good NPV and IR, no financiers will touch it. Mind you, I also know, as someone who has done a lot of studies, if the job was executed as per the study the costs would also be legitimate, it is often when people try to get cheaper (Cut corners) that things actually get a lot more expensive (lost schedule costs way more than people think).
Now that I've got the agreed parts out of the way, I would point out a few things which I believe we disagree on.
Cut-off grades are NOT linked directly to ONLY strip ratio. There are several factors and GRADE is one you've conveniently overlooked here. Guyere is a low grade (1.1 g/t proven and 1.3g/t indicated) deposit, thus low strip ratios are required. Wiluna OP and UG grades are 2.8 and 4.4 g/t respectively. Meaning the strip ratio for the same cutoff grade should be around 2.5 as large. Also of note, with cutoff grades is more about overall economics including scale. Gruyere kept their cutoff grades relatively high for their deposit to keep their AISC relatively low. Blackham has done the opposite, which covers the gap.
You could call that creativity but every mining company does that to enhance their own deposit. Gruyere is looking at $945/oz AISC, over $120/oz lower than blackham was targetting in their FS with the same cutoff, lower grades, higher recoveries and similar oz/year.
80% recovery at 2.8g/t is still a lot more gold per tonne than 91-94% recovery at 1.2g/t (2.24 g/t recovered vs 1.13 g/t recovered). Gruyere also stated processing is half their costs, so their strip ratio and cutoff grades needed to be tighter for economics. Their ore is hard (BWI of 16) and highly abrasive, meaning they needed to keep mining costs low to offset higher processing costs. They also needed scale more than BLK because of the lower grade and hard ore.
So yes, I take your comments as wise (not to simply trust) but I also remind you to level the playing field with all variables rather than taking a one-sided view. It is also good to note that you, not I, was the one who originally placed faith in a BLK DFS when we discussed the current OP oxide feasibility and it's valuation method. I did not bring this up originally, so I find it a tad hypocritical that now you're taking them with a grain of salt.
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