Literally everywhere in the West there are legends of lost treasure, be it "Spanish," "Indian," or something else. This has inspired many people to write about the subject and publish their material.  A few authors have fairly explained that these are legends unsupported by any kind of historical documentation.  Others have written as though everything about the legend is 100% truth. Generally, there is a pattern to these stories. It was an "old" Indian or an "old" Spaniard or Mexican; often it was an "old" prospector who only came into town once every year or two for supplies; other times it was a nebulous "Spanish conquistador" or bedraggled  "Jesuit Padre" who limped into some remote outpost and in his last tortured breath bestowed a map or written document upon another nebulous person who heard his dying confession. This makes for fascinating reading and has produced thousands of dollars in books sales over the years.
       Treasure authors often fault historians for giving misinformation  -  especially about the Spaniards  -  and certainly, in some instances they have a valid point.  History is always changing as new information comes to light. For the majority of the population, including native Spanish speakers, ancient Spanish documents are not readable, making the interpretation of Spanish colonial history even more difficult. However, for anyone willing to spend the time to train themselves in reading Spanish paleography (ancient handwriting), old Spanish documents are just as comprehensible as any other document written in any other language. It would thus behoove the treasure author (or treasure hunter who reads his material) to train themselves in reading such materials. Then, if new information comes to light that changes our understanding of history in some way, they could publish facsimiles, transcriptions, translations, and their interpretation of the alleged documents so that we all could learn more about our past.
          Unfortunately, that is not the case with the average treasure author. They are in the business to make money from their book sales, not to add to the general canon of historic information. Beware of the author or artifact salesman who claims to have obtained a map or document from a "museum in Mexico," or an "archive in Spain." If they do not cite the particular museum or archive, they are probably selling you a fraudulent bill of goods. If a treasure author claims to have worked with archives in Spain, find out the name of the archive and archivist and contact them before wasting a lot of time, energy, and money on searching for lost treasure. The real "treasure" is in the money gained from writing treasure stories. If that were not the case, the treasure author would have long ago gone out and found the "hidden gold" and not bothered with the immense amount of work required to write and publish a book.