Actually Phil, this was discussion oriented to Tolkiens total system of magic, and how his theory of magic applied to the case of turning lead into gold.
Stylistically, Tolkein used the Rabbinic method of story telling. Magic wasn't just magic to him, it was sacred and a metaphor for grace. Thus using magic for a profane thing, like changing lead into gold, was tentamount to blasphemy. Get the background thread now?
True, but I think you missed the point, again. Gandalf was very powerful - but even Gandalf didn't change lead into gold. This means that Tolkien didn't think alchemy was a worthy use of his "sacred" magic. Thus, the conclusion may be drawn, that Tolkien though changing lead into gold was rather silly, and too "super-fantastic" [my words] and irrelevent, to include in his books.