Important object in the history of mankind, graphite from CP-1 (Chicago Pile 1), the first nuclear energy reactor which launched the first successful atomic energy experiment, giving life to the nuclear age. Enrico Fermi conducted the experiment on 2 December 1942 at the University of Chicago, reaching critical mass for a self-sustaining reaction at 3:25 pm, and lasting for 28 minutes. After the experiment, a coded message was relayed to James Conant, Chairman of the National Defense Research Committee, and the Manhattan Project was underway, leading to the creation of atomic energy bombs less than three years later. Stick of graphite measures 3'' x .75'' x .75'', encased in a lucite block measuring 3.75'' x 2.875'' x 1.25''. Graphite block is identified on front, and has ''Argonne National Laboratory / University of Chicago'' on its side. Other CP-1 graphite examples are housed at the Museum of Science and Industry in Chicago, and at the Bradbury Science Museum in Los Alamos. Consigned by a retired firefighter who worked at Argonne for 40 years. A very rare and important piece of the first nuclear energy reactor that changed the course of history.