Go to your Grimore, then click enemies, then click books of sorrow (these are the calcified fragments) note that it will not tell you what you are missing on each character it only shows it for your entire account.

Not sure if possible on iPhone, but thru the website on a computer you can go to each character's "progress" and see which you are missing per character. Also, to find the missing fragments there are plenty of videos on YouTube or website for that