Beyond The Ordinary
In the TV show, Arthur Conan Doyle's The Lost World Series 3 Episode 19: Tapestry, Challenger talks about a batch of iridium metal that was stolen from the British military. Interestingly, Challenger says that the batch number of the stolen iridium is Alpha Bravo 42 = AB κ.
Playing the role of Challenger, I personally choose as my 'metal of intrigue', the transition metal, Rhenium. π below.
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Beyond The Ordinary
As a piece of The Cosmic Qu Jigsaw Puzzle, you can't do much better than the element Rhenium. For one thing, as stated on the image, the Rhenium atom has 75 electrons in it's atomic shells. In order to maintain overall electrical neutrality, the Re atom has, in it's nucleus, 75 protons. Also in it's nucleus, Re has 111 neutrons. These 3 numbers should be familiar to you by now and their significance, in Qu, understood.
111 = 3×37. 1/137 is (very nearly) the value of the fine-structure constant, α. Remember the above discussion of iridium batch alpha (α) bravo 42.
We note here that 75+75+111 = 261 = ⳨(216, E).