Amon Sûl-stone
The Stone of Amon Sûl was a palantír that rested on the Arnorian Tower of Amon Sûl
In T.A. 1409 the watchtower was burned and destroyed when Angmar's forces overran Arthedain. Its last King, Arvedui, saved the palantír as well as the Annúminas-stone.
With these and other heirlooms, he fled into the far north, where he was given shelter by the Lossoth. At last a ship from the Grey Havens came to rescue Arvedui, but after he had boarded, its hull was crushed by the ice, and all aboard were lost. The Stone of Annúminas, along with that of Amon Sûl, were lost in the shipwreck, and sank.