Question: Since kryptonite obviously doesn't come from Earth, how can Earth elements be used to create a synthetic version? Like in "Man of Steel", when Jonathan says that the Krypton key wasn't made from anything on the periodic table, so it couldn't be from Earth.
JohnShel91
3rd Feb 2016
Chosen answer: Kryptonite is a compound created by irradiated fragments of Krypton rather than a pure element, Synthesizing it would then be a matter of analyzing the compound and finding Earth elements with similar properties. (Some, as you say, would be beyond the knowledge of human science, which is why Gus looked at his cigarette pack and decided to use tar in the place of the unknown elements).
Captain Defenestrator