Castle in the Sky

An airship carrying Sheeta, a girl who has been abducted by government agent Muska, is attacked by Captain Dola and her air pirate sons who are in search of Sheeta's crystal amulet. In the resulting struggle, Sheeta falls from the airship but her descent is slowed by a mysterious power within the amulet. She safely lands in a small mining town where she is discovered by a boy named Pazu, who takes her into his home to recover. Pazu tells her of a mysterious floating island named Laputa which is visible in a picture taken by his father. Later, they are pursued by Dola's pirates, and then by Muska's soldiers. Eventually, the two fall into an abandoned mine, where they encounter the local eccentric Uncle Pomme, who informs them that Sheeta's amulet is made of 'volucite' crystal ('Aetherium' in the American release), a material used to keep Laputa and the other flying cities aloft. Read more on Wikipedia.