RE: Question to Exgoldminer Lots of variables here, but I'll throw out some arguable, ballpark figures.
In North America, a typical underground operation needs about .1 ounces/ton, while open pits can run from half to less than half that. Depends on the type of host rock, distances involved, fuel costs of the day, general climate, costs of local labour. You can bet that labour, licensing and similar costs are way cheaper overseas. May not be any reclamation plans/bonds that need to be posted either
Different types of milling come into it, ie heap leaching, which is basically just piling up a bunch of ore and running cyanide through it, is less effective but much cheaper than a carbon-in-pulp setup.
How well-established is the mine? Late model equipment (paid for?), crackerjack workforce?
When you see a consistent average over a long period of time, it's probably a combo of low-grade oipen pit much augmented by high grade ore from underground, rationed over time to keep that grade consistent.
Biggest consideration, obviously, is the price of gold. Whether the admin has forward-averaged sales also comes into it.
Lots of reading out there, like https://goldinvestingnews.com/world-class-gold-deposits