I purchased some mammoth ivory a few months ago to put on some "special" bows. Just put some on a bow last week. I used a thin strip over some phenolic...and where the string actually rests I filed through the ivory so the string is actually resting on the underlying phenolic overlay. I didn't want the ivory to carry any load and possibly crack. It is much ivory, but it is there...and it is estimated to be 10,000-50,000 years old.
I used CA gel.