"The raw metal value of the average precious metals is $587/tonne at current prices. The average vien width is 0.62m, so if we dilute the grades to a mineable width of 1 meter, then the value of the diluted gold is $264.50/tonne and of the diluted silver is $99.36/tonne."

The material excavated to the 1 meter width would not be processed, it being considered as chaff so only excavation costs apply to that portion.

Are you taking that into account when devaluing the price per tonnage? Seems to me the devaluation is a bit steep.

Perhaps the difference is inconsequential.