draconite

noun

1. A mythical gemstone taken from the head of a live dragon and believed to have magical properties.

   “Dracontites is a stone that is forcibly taken from the brain of a dragon, and unless it is torn from the living creature it has not the quality of a gem; whence magi cut it out of dragons while they are sleeping. For bold men explore the cave of the dragons, and scatter there medicated grains to hasten their sleep, and thus cut off their heads while they are sunk in sleep, and take out the gems.”

   “Reject it not because it proceedeth from one which hath been lewd, no more than ye would neglect the gold because it lieth in the dirty earth, or the pure wine for that it cometh out of a homely presse, or the precious stone aetites which is found in the filthy nests of the eagle, or the precious gem draconites, that is ever taken out of the poisoned dragon.”

   “But there is another thing known about this (Grail) stone, called the Draconite. It is 'endowed with extraordinary powers (potentissimus valde)'.”