The Land Before Time VII: The Stone of Cold Fire.

Littlefoot and his pals set off in search of a "stone of cold fire" that fell from the night sky. Since he's the only one who has seen it though, nobody really believes him. Petrie's uncle Pterano offers support only because he thinks the stone has secret powers and wants it for himself but conceals this from the rest. The young dinos must figure out the truth, before Pterano gets the power.