Not sure where you obtained your figures from but the $75m to...

Not sure where you obtained your figures from but the $75m to $100m does not seem to be much capital expenditure. CAI is spending $120m to develop a gold mine to produce 90koz pa at a grade a bit over 1gm/t which includes underground as well as open Pitt. They have a very good return at current ZpIG.

BGL cap ex is $255m (underground) to produce 150k oz pa with a grade of 8gn/t while GOR (open pit) spent nearly $600m to produce 300koz pa at a grade a bit about 1gm/t.

Capital expenditure and the economics of a mine depend on more than just grade - eg metal being mined, size of mine, annual production, type of rock, recovery %. underground vs open cut, etc.

Sorry to say but both these posts seem to be too simplistic.

Azure was planning to spend around $70M to build the Oposura mine in Mexico which would do around a 1000 tonnes per day.

The CAI capex to build the Warrawoona mine is for production of 10,000 tonnes of ore per day at a strip ratio of up to 4 to 1, so that could mean mining around 50,000 tonnes per day. Based on what Azure is finding so far at Andover, I think that producing 750 to 1000 tonnes per day (like what was projected at Oposura) would be a good start.