Ithilmar

Forged by Elven smiths, Ithilmar is a priceless metal known for its lightweight and durability; it serves as an excellent alternative to steel or iron mail. However, given its rarity, ithilmar metal is rarely found anywhere outside of the Elven Kingdoms. On occasion, an ithilmar weapon will surface, sometimes as spoils of war, especially among the treasures of Norscan raiders who frequently raid Elven coastal settlements.

Ithilmar Mail
Among the Elven merchants who trade in the great cities of the Empire, a few, especially among retired warriors, keep suits of exquisite chain. Light and durable, ithilmar mail represents the height of Elven armoursmithing. While not magical, it's rumoured that only the greatest of Elven wizards can forge it. Universally, such armour never impairs the movement of its wearer.

Source

 * Warhammer Fantasy RPG 2nd ED -- Old World Armoury (pg. 18, 42).