Thanks for the added info PB. So it sounds like nothing was really said of what resulted from the first, motivated the second long hole.
As I understood things, the first long hole was mainly to prove up geological structure. Yes, there was a chance that they would have good assays at either footwall on the porphry's borders, and there was also the chance of finding grade of potential value within either disseminated in the host or collected in fractures if such exist. The other part was that it would possibly provide information about the nose fold. No doubt much info is to be attained from the nature of the host, its degree of alteration and where, chemical composition and where, etc. that might help indicate which in direction things happened and in which prospects might be better.
You describe the problem with proving up a resource in this model well. Lots (one hopes) of veins, many of which might not be economic to mine . . . consider following a vein a few inches across, even if almost pure medal, when the minimum cross-section one needs to excavate is maybe 6 foot by 4 foot . . . lots of tonnage that is waste and all at the same cost per cubic volume to excavate. It is when a major vein is found. Following that, and side excavations on the "tree" of veins found connected to it, is what is done. As you said PB, with a drill hole one could pass close, but miss, and not know it. Underground drilling obviously is much cheaper as one can put out many shorter closely space holes from a drill turnout for the same cost as one drill from surface, giving a much better chance of getting info on the deposit structure for the same money (after the decline to depth is paid for that is).
Cheers
AI
