Draconites
otherwise dentrites, draconius, or obsianus, is described by Albertus Magnus as a shining black stone of pyramidal figure. It is not very easy to obtain, as it must be taken out of the head of a dragon, cut off while the beast is still panting. It subdues all sorts of poison, and endows its possessor with invincible courage. The kings of the East esteemed it a great treasure.