Where would you have a chance to locate one? I'm thinking anywhere along the Texas or Florida coasts, also any territory that once belonged to Spain, near or in a big city, around an old hacienda, well, almost anywhere. If they are that rare, they could be anywhere north or south of the Rio Grande, though in 1659 northern Mexico was still pretty wild and Texas was wilder, near or on a Carribean island(especially Cuba, Puerto Rico, Dominican Republic...). Like the man said, gold is where you find it. I fear that it will be a lucky accident that turns one up. There is one more place. Spain itself now, in a shop, attic, kid's coin collection...Who knows. Probably less chance of finding one of these as there is of Sofia Vergara knocking at my door tonight carrying her jammies and toothbrush.