Why does Thrór not save the Arkenstone?

The Arkenstone is discovered during the reign of Thrór - rather than that of Thráin I - and never leaves the Lonely Mountain. It is considered a divine symbol for the King under the Mountain to rule, and is fastened on the king's throne. During the Sack of Erebor, Thrór fails to save it as it falls into the great hoard of gold.

What does the Arkenstone symbolize in The Hobbit?

2012: The Hobbit: An Unexpected Journey: The Arkenstone is discovered during the reign of Thrór - rather than that of Thráin I - and never leaves the Lonely Mountain. It is considered a divine symbol for the King under the Mountain to rule, and is fastened on the king's throne.

Where can I find the Arkenstone?

It seems unlikely that something that valuable wouldn't have been dug up at some later date by goblins or orcs, or some other creature. As a matter of fact, the Arkenstone can currently be found in the Tower of London under heavy guard.