LucidBeast writes: "Xenon the second heaviest of the noble gasses is only found in trace amounts in the atmosphere. Atmosphere contains less Xenon than other lighter noble gasses. Missing Xenon has perplexed scientists and it has been speculated that it is hiding in the earths mantle. Now a group at the University of Bayreuth in Germany think that they might found the answer. I turns out that Xenon does not dissolve easily into Magnesium silicate perovskite, thus it cannot hide there. And because it had no place to hide it is now gone forever."