Regardless, the Germans could never have refined enough uranium to build one by 1945.
The atomic pile that was built under the bleachers at Stagg Field in Chicago was as big as a house. It was designed to be a sphere, but when it became clear that it would become critical long before they reached the top, they truncated the upper courses of carbon blocks and uranium slugs, so that in the end it was shaped more like a doorknob as big as a house.
It needed to be so big in order for the graphite moderator to slow the U-235 emitted neutrons from the tiny fraction of that isotope in the natural uranium used to fuel the pile enough to have a decent probability of being captured by other U-235 nuclei, and thereby create a chain reaction.
I seem to recall reading somewhere that a German A-bomb would have required a cargo ship for delivery.
Search your attics, folks. And remember, Rick from Pawn Stars is always buying. He’ll have his expert look at it to make sure it’s an authentic uranium cube and go from there.
As far as I know; the Germans had no way to enrich natural uranium; which is over 99% non-fissionable U-238 and only about .7% U-235. Perhaps in fractional-gram quantities. Without the enrichment, there is only the possibility of creating a low power chain reaction, as did Fermi in Chicago at CP-1. using over 5 tons of natural U.
An additional requirement is a moderator to sustain a chain reaction in unenriched U by slowing down neutrons and increasing the odds that said neutrons could be captured by another U nucleus. Szilard theorized that carbon; in the form of graphite, would make a suitable moderator...but critically, the Germans were not aware that a common impurity in graphite, Boron, was a voracious neutron absorber. Graphite was commonly used for arc-lights at the time and the boron impurity did not present a problem for that application. But not knowing this nuance, the Germans rejected carbon and believed they would have to produce thousands of gallons of heavy water. Which they did at Norsk Hydro; a plant that was bombed by the Allies. The US reactor effort was 100% dependent upon the development of low-Boron content graphite which was produced after Szilard went to National Carbon and persuaded them to produce what was and is called “nuclear grade” graphite.
The Germans in reality were nowhere near being able to produce a weapon. That’s not to say that the fears of them doing so were unfounded. They certainly led the world in chemistry in the first half of the 20th century.
Cool artifact. I think you need a license to hold more than 1kg. I have a little sliver around here somewhere.