I've been trying to remember the name of this movie that I watched when I was really young. It's a kids movie about a young boy who finds a green rock/stone, which is an alien, and then has to run from the bad guys in order to protect his alien/rock friend.
It was a glowing green stone and I think somehow it communicated with the boy and it had some sort of powers.
The only other thing I remember is that the alien leaves in the end and the boy gets really sad.
It's definitely not E.T., I don't think the movie was a huge hit. It's also possible the movie is from the 70's.