[chris (OP)]

There are many examples of meteorites said to come from other planets, like this "Martian" meteorite for example:

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(Image public domain and courtesy of NASA).

But how did the person who found this know it was from Mars? What have we got to compare it with to confirm its identity?

Chris

[Don_1]

Did it have 'Mars' written through it?
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[chris (OP)]

I guess no one can help me with this then?

[Chemistry4me]

NASA had this to say:

The conclusive evidence that the SNC meteorites originated on Mars comes from the measurement of gases trapped in one meteorite's interior. The trapped gases match those that Viking measured in the martian atmosphere

http://www.scienceagainstevolution.org/v1i2f.htm