There was some discussion on this topic a few years ago. Let's see if my memory serves me well enough to help you a little. From what I recall, meteors have Iron and nickel in them. And just like the pics above have a melted surface area. Many of the ones found have rust deposits on the outside as well.
If I remember right, you will get a nickel reading on your detector. But there will also be a slight attraction to a magnet when hung on a string. The only reason I remember this is I thought I found one once and researched it a bit.
Good luck with your hunt. Just be sure that if you find a good one, it's on private property. (wink) You don't want the government taking it away from you.