The Final Part of "The Colors Out of Space"

Silver Kryptonite. The cover blurb for Jimmy Olsen #70 promises that "Nobody … but nobody … will guess … 'The Secret of Silver Kryptonite'!" Well, don’t tell Mort Weisinger's ghost, but … I did.
This story is a masterful study in induced paranoia. Jimmy Olsen runs around to the curator of the Superman Museum, mermaid Lori Lemaris, Supergirl, and Clark Kent, asking the same thing -- is there such a thing as Silver Kryptonite? what about Silver Kryptonite? After all this, Superman starts wondering too -- especially since he didn't think there was such a beast. He trails Jimmy to a special lead-lined lair staffed solely by Professor Potter. While all those secret things are going on that he can’t observe, the Man of Steel is going crazy with suspense, and maybe even a little fear. I mean, sure, Jimmy and Potter are his friends. But why are they so interested in Kryptonite -- especially this new, mysterious variety? Finally, though, all is revealed: "There is no substance as Silver Kryptonite! This is just a silver box containing statuettes of your closest friends on Earth!"
But why? Here's a clue: Jimmy Olsen #70 is the July, 1963 issue. It's the year of this issue that clinches things: "It's the 25th anniversary of the day you adopted Metropolis as your official home,. Superman," in June, 1938's Action #1. The only thing is, in those 25 years, nobody has aged much, have they?

But, wait -- there's more! Here are a few lesser, one-shot Kryptonite appearances:
Action #277 tells how Luthor generates a trap for Superman involving yard-wide floating globes of Kryptonite: "My machine can manufacture synthetic Kryptonite of any kind," he gloats, including "another one -- Yellow Kryptonite! If Superman ever got within range of its deadly radiations, who knows what bizarre effect it might have on him?" But it turns out that all the Kryptonite, even the Yellow kind, is fake -- all part of a hoax to scare and humiliate Superman.
The Supergirl tale in the same issue depicts the Maid of Might's arrival, accompanied by Krypto and Streaky, at an odd planetoid that generates strange things and creatures at random, much as on Star Trek's "Shore Leave" episode. It turns out that the place is the automated "Headquarters of the Interplanetary Multi-Dimensional Practical Jokers' Club." It can, among other things, grant wishes. So when Supergirl encounters a Green K fragment, she wishes. "Wishing Well, I wish the Green Kryptonite below to change into harmless False Kryptonite -- forever! My super-vision reveals the wish worked!"
Several times, artificial forms of Green K have been concocted. In Action #226, Luthor uses an atom smasher to develop a synthetic isotope of Kryptonite." And World's Finest #132 tells how, on an adventure in the past, a Batman imposter gets a medieval alchemist to brew up a bunch of synthetic Kryptonite. As they say, kids, don't try this at home!
Jimmy Olsen #92 tells how Truff, an invader from the planet Pyron, is paving the way for a full-scale invasion of Earth. One of his weapons is the dreaded Magno-Kryptonite: "Its magnetic properties make it cling with unbreakable force to anything that comes from Krypton." Boy! Talk about static cling!
Well, friends, thus runs the tale of the many forms of Kryptonite. I hope you learned something to impress your friends with. So, the next time you visit your old neighborhood and find that your favorite vacant lot or playground has been turned into a Walgreen's or a weight-loss clinic, remember that it could be worse. Be glad your whole block wasn't turned to Green Kryptonite!