Illithium Ore is an item needed in the side quest Gain the Services of Sir Sarles for the Temple. You need to bring this to Sir Sarles in order to convince him. Afterwards, you discover that he tried to give you an impossible task to get rid of you. This item appears in Baldur's Gate II: Shadows of Amn and Baldur's Gate II: Enhanced Edition.
|“||This is 200 stones of pure illithium ore. Illithium is renowned for both its luster and its unique property of never becoming soiled.||”|