Comparison of the specific geological strata found in the Rosemont and Hay Mountain might be important, as it seems the ore bearing layer at Rosemont is present at Hay Mountain, but less deeply buried. I'm not sure of the accuracy of that statement and would like to know for sure. Also, of course, the fact that the same geological stratum is there at Hay Mountain does not prove that it is contains commercial mineral. Drilling is needed to determine that.
However, it seems to me that the case for drilling is continually being improved and better understood.