Can't add much to this discussion, Brewer, since I've never had a kidney stone of my own. Once, a student of mine brought his mother's kidney stones into the classroom for a little "show and tell" action. My principal was a "born again" rockhounder, complete with homemade bolo ties and massive stone and silver belt buckles. He had a standing offer to identify any rocks we would bring to him, so I took the kidney stones to him...just to see how good he was. He hemmed and hawed, held them up to the light, mumbled something about greenstones, and after a contemplative moment asked, "Where'd they come from?" Lucky for me, he had a good sense of humor.

Here's some music to help get you/your stone moving. It'll sound pretty good after the tenth or twelveth Keystone. Have a safe passage!

http://www.youtube.com/watch?v=WtMPlY3duz4&feature=related