Iron Dragon Mountain was a mountain in the Earthfast Mountains of north Faerûn, between Impiltur and the Vast. It was a legendary hidden peak and home to greatest temple of Deneir in the Realms.
mist dragon Ouranalathra the Mistmaiden once laired at the mountain, before she moved to the Lake of Mists in the Endless Wastes. Afterwards, it gained the name of "Iron Dragon Mountain".
Afterwards, it gained the name of "Iron Dragon Mountain" and became the site of the
Master's Library, a temple of Deneir with the greatest collection of books in the world. 
It is implied that the mountain is named for Ouranalathra. This is explained in
George Krashos's unpublished, non-canonical article, , which tells the history of Ouranalathra and the Master's Library.
Ouranalathra, "the Mistmaiden"
Julia Martin, Eric L. Boyd (March 1996). . ( Faiths & Avatars TSR, Inc), p. 55. ISBN 978-0786903849. ↑ 2.0 2.1
Eric L. Boyd, Eytan Bernstein (August 2006). . ( Dragons of Faerûn Wizards of the Coast), p. 144. ISBN 0-7869-3923-0.