If a vein is 0.5 metersgrading... I'm not looking it back up. But because the true width is expected to be 70-100% (because they drill at an angle... it might be only 0.3 meters.. we don't know). Is that worth moving 700 feet of stone to get at and make an underground mine? I don't know.
I could understand if the vein was 30 meters thick. But if it is only a few inches. That is a lot to move to get to that vein.