[Mezzaluna]

Phil,

Thanks for the tip. I went back to Order of the Phoenix and found a passing reference to a locket that nobody could open. It's near the beginning when they're cleaning the Black mansion.

Also, there's a reference in Half-Blood Prince several times to Regulus Black, Sirius' brother. He had been a death eater, but survived only a few days before he was killed. Since the note which was left with the phony locket was signed "R.A.B.", I'm betting that locket at the Black mansion was the Horcrux. Kreacher not doubt knows its whereabouts. Harry sent him to Hogwarts, so now he'll be nearby for questioning when (or if) Harry returns to school in the fall.

Being retired is fun!