its a little out of date.. $25 per gram gold.. article is from...

its a little out of date.. $25 per gram gold.. article is from 2017
i'd hazzard a guess to say 1g/tonne is about break even for open pit... but if in a country where costs are lower it might be profitable.. especially if its a bulk prophory system. considerably higher grade is needed to make underground viable.. im not sure what the number is but id think it would want to be 3g/t or better.
porphory copper is mined as low as 0.4% that ive come across
ideally you dont want to be in the lowest quartile of profitability on any commodity.. because when the price has a down cycle you would get smashed and go on care and maintenace... or mine at breakeven at best... possibly fold too

from all accounts .. we have the rock types in zone B that match the rock tpes with those nice grades mentioned from rock chip sampling in the previous mentioned articles/papers.. and if we have an aeromag done mid year.. we could be starting drilling by Q3 2024 maybe first results Q4

there's also geology / metallurgy to take into account.. its a bit more complex than just grade alone.. a nice bit of info covered here, worth a listen