What's this movie from my childhood?

Hi everyone,

I can't seem to remember this movie so please help me out if you can! So the movie is about a rock or stone or an artifact arriving from space or it's already on earth or something. A teenager found it, he touched the stone or kept it or something. I can't remember if it gave him power or slowly turning him into an alien? I'm not sure if it was a horror movie or not but I think it involved aliens. It was definitely before 2008 and I remember a bunch of people trying to save the teenager or kill him?