While I don't know about the effects of Aqua Regia on organics, I do know that Aqua Regia was known to medieval alchemists, and so names because it was the "king" of acids. Regia is very strong, and is so caustic that you need a special container to even hold it (wax, maybe?). Similar in strength, though maybe impossible to manufacture, is Hydrofluoric acid (HF).
I don't really know where Fluorine exists naturally, but I'd guess it could be found in salts, similar to table salt. If an alchemist added a Fluorine salt to water, and made the water hot enough, the H would bind to F, and the Metal (probably Na) would combine with O. I don't know how hot that needs to be, but magic can be wonderful stuff =P.
-nameless