• Furnace Stone
• Item Level 219Disenchants into:
  [Abyss Crystal]: 1-2
• Binds when picked up
• Unique
• Trinket
• Requires Level 80
• Equip: Increases your dodge rating by 105.
  Use: Increases armor by 5152 for 20 sec.
• Sell Price: 11 39 40
• Cooldown: 2 minutes

Source

This item drops from Ignis the Furnace Master in the 10-man version of Ulduar.

Patch changes

•  Patch 3.1.0 (2009-04-14): Added.
  

External links

• Battle.net (EU)
• Wowhead
• Thottbot
• WoWDB