You might check with Mama's Minerals in Alberquerque, NM.  I don't think 
they have it listed on their website, but when I was there in person 
they had quite a few different types of bulk stone (lapis is the one I 
remember clearly).  Might be worth a call at 1-877-WE-ROCK-U.  Fair 
warning, they are a bit new-age.