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.