I haven't passed golf ball sized stones, but did pass a number of marble-sized stones during my last flush (7th flush). There were various colors - some black, some white (calcified?), and some green. There was one that had the trademark "mercedes benz" marking on it, just like the one in the photo on this web site. I understand that this type comes from the gall bladder. I don't think it was formed in the small intestine. Any ideas about that?