Take the Meteorite and give it to the Professor for TM 27 - Return.
Anyway when you say you've been to Mount Pyre, I assume that means you've beaten Norman, gotten Surf and everything.
On Mt. Pyre, there's the Red Orb and the Blue Orb. One of the has been taken by Team M/A, depending on your version. The old lady will give you the other orb that hasn't been taken. Now fly to Slateport City.
Have you gotten the Orbs yet?
Anyway you can check a walkthrough here or here