A 2 cm square by 5 cm long sample of graphite from the world’s first reactor, the Chicago Pile (CP-1) which heralded the start of the nuclear fission age on 02 December 1942 at Stagg Field, the University of Chicago. The sample is cast into a clear plastic block which measures 9.5 cm in length and has a cross-section measuring 6.5 cm by 3.5 cm.