Is it possible to find Mewtwo in pokémon X, if so, where? Also where can you find mewtwonite?
In Pokemon Village, there will be a cave. It's called Terminus Cave. Mewtwo will be in there. After you catch it there will be a Mewtwonite.
Here's a video of Terminus Cave: http://www.youtube.com/watch?v=FvUbFX36SVg