I will have to do some digging but remember seeing 0.3g per ton as a cut off grade in at least one project. Here is the part of the report dealing with grade. The 1.7 g/ton appears to be right:
I’ve talked about this in the past, but I’m
going to update you because I think the
update is quite compelling and quite
bullish. I’m going to give full credit for this
data to Mr. Barry Cooper, the Senior Gold
Mining Analyst at CIBC, who has done the
work on this. He has calculated the
average grade being mined each quarter
by the top 42 gold mining companies on
the planet. He provides a chart going back
to the 2005 first quarter, showing that
average grade mined was about 1.7 grams
per tonne or 1.7 parts per million.