I know the instrument used at the end of Crystal on the Buckingham Nicks album was an oboe, like Keith Olsen said, but I could SWEAR that the one at the end of Crystal on the Fleetwood Mac album is a piccolo!!! Unless it was somehow manipulated, it sounds way too high to be an oboe or even a flute.
Just had to share that thought.
Maybe I'm just trying to convince myself that the piccolo can be used for good and not for evil ... lol.