Meerkat
I get the impression that you may not have read the original post correctly.
The original post said:
That's 4.5 million cubic metres of estimated mineralised volume, which at a rock density of 0.34 cubic metres per tonne......
OK that's 0.34 cubic metres per tonne
Sounds perfectly reasonable to me.
I can't see anywhere that Cougar suggested that a cubic metre of rock weighs one third of a tonne.