Cleft-Asunder
Chanca piedra (aka Bhumi Amalaki) can be found at kalyx.com. I normally buy every herb from mountainroseherbs.com located in Oregon, but they dont' seem to have it. I really recommend MRH because their stuff is top quality and all of it is under their name, rather than a place like Kalyx which is just a distributer of many different brands.
Chanca piedra is said to remove stones, yes, I'm sure. Also, gold coin grass (lysmachia) does for sure as well, and I know this from experience.