SSM: There are four general categories of treasure hunting literature:
I. Fact: Perhaps this is the rarest. There are excellent "how-to" handbooks and manuals, works of history that are factually correct, biographies and autobiographies, etc.
II. Folklore: Prof. J. Frank Dobie is the obvious example here. Often founded in fact, these yarns and legends will generally have a good deal of barren rock mixed in with the valuable ore.
III. Fantasy: These are the stories written by those who claim to be successful treasure finders - but the writers fail to produce any real evidence to back up the claims. F.L. Coffman, Lieut. Harry E. Rieseberg, Frank Fish (including that name won't make me any more popular here!), Jennings in the book by Robin Moore, the much more recent W.C. Jameson is their direct literary heir, and far too many more to count. In many respects these are the least worthwhile contributions to the literature because serious people may well mistake them for fact.
IV. Fiction: Novels and short stories can be very instructive. There's a great deal to learned, for example, from the classic Treasure Island. Recently here on TN a thread was started asking for the desirable traits in a treasure hunting crew. Being lucky wasn't mentioned - but generals from Napoleon to Blackjack Haskins have valued that trait above all others. Many of the posts reflected the hard won knowledge found in The Treasure of the Sierra Madre (and as good as the movie is, the book is still better). A recent personal favorite is the first-rate Plunder of the Sun.
Where does an author such as Harold T. Wilkins and his many accounts of pirate treasure maps belong? Keep him out of "Fact" and he'd fit into either Fiction or Fantasy.
Now - to determine in which category any book or article belongs? That's the art, now isn't it...?
Good luck to all,
The Old Bookaroo