The universe keeps smashing things together, and occasionally invents an entirely new solid while doing it. Nuclear detonations have produced odd glasses and previously unknown crystalline combinations inside scorched test debris. Lightning can fuse soil into branching tubes of glass called fulgurites, trapping minerals in arrangements they would never adopt during a respectable afternoon. Hypervelocity impacts do something even ruder. They squeeze, heat, fracture, melt, and quench rock within seconds, sometimes forcing atoms into dense structures usually found deep inside Earth. It’s a big bang, though not quite the Big Bang, and considering all of the above, I can only assume kryptonite is a serious quality-control failure from an alternate dimension..