sasnz is right: most of these "stage coach robberies" and "lost mines" are just embellished stories, superstition, etc.... Based perhaps in a kernal of truth, but then gone-wild. How many more "dying miners crawling into a wild-west saloon, the last survivor of an indian attack, reveals a lost mine, *just* before he dies" can you take? The problem with robbery stories, is someone gets on old 1880s newspaper microfilm and reads that "The loot was not recovered", and makes the automatic assumption that "it's not recovered". But you have to remember, the person writing that article back then was at the whims of whomever he was getting his info from. Who's to say it wasn't recovered and spent by either the crooks, or the posse that chased them and *claimed* not to have found it? Do you really think that if Joe Blow that same year went out and found it, that he'd be making a followup article "I found it"?
But it doesn't do any good. The human psyche wants SO hard to believe in treasure lore (so as not to be "left out"), that we accept any written sources as gospel truth. Afterall, it's in writing, "so it must be true"? Having worked on plenty of police evidence and stolen loot recovery cases, and then subsequently reading the articles in the next day's newspaper, I can tell you that .........100 yrs. from now, a lot of assumptions are going to be based on stories, where whatever got there, passed through the filter of whomever was telling the paper. It could only have been worse back in the 1880s/90s when sensationalism sold newspapers.