This map shows up from time to time in the San Saba legend, often as a translation of a Spanish waybill. It shows a lot of mines around Menard. Unfortunately, no paying mine has ever been opened, and not for a lack of looking.
This map was actually drawn by an Emmett Sarver in 1927 in an apparent attempt to put all the alleged mines one map, based at least on part on an engraved rock said to have been found buried at the presidio. George Collins, of Kansas City, gave a copy of the map to J. Frank Dobie in late 1930, probably in response to the publication of Coronado’s Children.
Incidentally, George Collins was good friends with the treasure hunter William Longworth, and, in fact, it was Collins who wrote to Dobie to inform him of Longworth’s death.