After some research, I have come to the conclusion that there is a bug in the game, or on the website. According to bungie.net I am missing the XLV calcified fragment for completing the Oryx Challenge, but when I look at my grimoire, I have the card. Several websites are reporting that I have the card, and I know that I have done the challenge, but the game is only shows g 49/50 calcified fragments. Perhaps I should raise this issue in the bugs forum.