Since no one has ever been to Mars to take comparative samples, wouldn’t this be conjecture? Sure, they could have taken spectrometry readings of Mars, but all this seems like guessing and extrapolation.
"This rock is from mars. I can prove it and if you don't give me money, much bigger ones will soon be arriving." - Mars Science Chair @ Cal Berkley.
Certain isotopes are present that can only be expected in something from Mars....
On his Facebook page a good buddy of mine lists his old alma mater as “Mars University/Earth Campus’’. The school fight song is “Surrender Earthlings’’. I’ll have to ask him if this is really a chunk of The Red Planet.