RE:but why
Cost of mining it. Mining a deposit at surface is cheaper, so the cut off grade is lower. You keep typing cut of grade, the correct term is cut OFF grade. With EAG deposit what they are saying is that any deposit that is less than 3g/t is not economically viable to mine if the price of gold is $1,200. An increase in the price of gold will make a mine more profitable in 2 ways: 1) increased selling price less cost of mining results in bigger profit per ounce, 2) the size of the deposit becomes bigger as more of the deposit becomes economically viable to mine. Go to the EAG website and read through the last 43-101, try and find the page that lists the different size of deposit when the cut off grade changes. It might be easier to understand than my ramblings.