From what I have read (newspaper articles from 1870s - 1933), I believe the mine was a story invented by John Swift to cover his forgery of "silver" coins. He had a furnance and he made coins (Sprinkle coins?). Silver did not come from a mine but was from stolen items. Having a silver mine gave more legitimacy to the coins he made. There are at least five newspaper articles where someone thought they had found the mine, but later abandoned. The silver found at these mines were always a very low grade.
A lot of people spent their life and money hunting for this mine. One article stated James Harrod, founder of Harrodsburg, died while out looking for this mine.