"This stone radiates a brilliant yet sickly-coloured, yellow glow even in the dark. There is an odd rune carved into its surface."
These items drop from high level named mobs in The Delving of Fror.
You can win this item from the Lottery: Lottery of the Stalwart and/or Lottery of Rhovanion and/or Lottery of Angrenost of which you can enter at http://my.lotro.com/home/lottery.