There is a continuing off-shoot where we are all trying to make sense of this conundrum. It really looks like there is more unknown than known about these stones and what looks forthright one day can be replaced by something which looks like it disposes it the next day, only to find out that either may be right in further study... It's a real mystery. Anyway, the discussions are at: http://www.smartgroups.com/message/readmessage.cfm? gid=1423922&messageid=9504&startid=9507 and now also http://www.smartgroups.com/message/readmessage.cfm? gid=1423922&messageid=9520&startid=9527 If they only put up one post select to read the discussions by clicking on that part. so knock yourselves out. We're all learning and it looks like the primary causative factors for this type of stone are unknowns (unless found within the last two years in which case I'd love to hear about those journal articles, please, if anyone finds them) though a predisposing factor (the genetic variations which affect either cystine or the COLA combo of amino acids) is known. Thanks for all the info! It has been useful not only to know but also helping with my further searching so all the replies -- every one of them so far -- has helped a lot! (Granted some caused bouts of frustration -- as I'm sure you could tell -- when the picture got further muddled, but now at least I know WHY it was muddled so that is progress. It's muddled because of how much just isn't known at this point.) Again, thank you so much for the info, help and leads! [Posted in FML issue 4570]