http://www.superman.nu/tales3/return0/?page=1

Stages In The Development Of Kryptonite

(i) The original green Kryptonite that weakens and kills Kryptonians.

(ii) Red Kryptonite with bizarre, unpredictable effects.

(iii) Other colors with different effects.

(iv) The Smallville meteorites that not only weaken Kryptonians but also empower Terrestrials.

Smallville has made a major addition to the mythology.

Addenda: In Superman 3, artificial Kryptonite is green but has red effects.

Here, I suggest an alternative Superman origin story, that the pregnant Martha Kent was at ground zero during the meteor strike...