aweigh, I get your inference WRT OSKbut your numbers are haywire. You went from grams to ton in costs to mine.
20 times $26/gram is $520/ gram, not ton. Multiply by 31.1 to get cost/tonne. TILT!
Now $700/tonne rock is 17.5 timmes better than OSK, less cost variables. Your point is valid.
Cheers, WJ