Ann: Maiden Drilling Program Commences at Discus Copper Prospect, page-30

The US was cheaper when I was looking at such things.

That $100 per tonne for development is just the contractor rate excluding trucking. No owner costs, power, water etc. Stoping cost will be lower but still attracts the same overheads and cemented fill is not cheap if that's what they use.

Say level interval is 20m, ore drive is 5 high x 3 wide and stope is 15 high by 1 wide. The roughly speaking the ratio of development tonnes to stope tonnes is 1:1.

The Antler scoping study has development at US$98 and stoping at US$44 for a weighted average cost of US$52 per tonne.

Back-calculating the development tonnes (X) to stoping tonnes (Y) ratio...

X + Y = 9.3

(98X + 44Y) / 9.3 = 52

98X + 44(9.3 - X) = 484

54X = 75

X = 1.4Mt and Y = 7.9Mt

X:Y = 5.6

So at Antler expensive development contributes significantly less to the total mining cost than does cheaper stoping.