How is Excalibur broken?

In the legend of King Arthur, Excalibur is broken during the Battle of Camlann when King Arthur faces Mordred. After a fierce battle, King Arthur mortally wounds Mordred but is also fatally wounded himself. In his dying moments, Arthur orders one of his knights to throw Excalibur into a nearby lake. A hand rises from the water to catch the sWord and Arthur's body is then taken to Avalon for healing.