In a desert in New Mexico, near the town of Alamogordo, the desert floor is littered with small green glassy rocks. They look like they could be the fragmented remains of the Emerald City from the Land of Oz destroyed in some terrible disaster. The crystals inside the rock vary in size and shape, some of them have taken on globular rounded shapes and many of the rocks contain lots of air bubbles in the rock similar to those that might be found in igneous rock from a volcanic eruption - except there is no volcano near Alamogordo. If you were to pick up some of this rock you should do so with care; for starters, you're not allowed to remove it from the area - it's against the law. It's also radioactive - not very, being close to a small rock might give you a similar dose to sleeping next to another human being every night - but the isotopes contained in these rocks include Strontium-90, Americium-241 as well as traces of Plutonium-239 and Plutonium-241. Strontium-90, if ingested, behaves in a biochemically similar way to Calcium and could be absorbed into bones, which would result in a build up of radioactive isotopes in the bones, resulting in bone cancer.
These rocks are special: they are chemically and isotopically unique, and they were formed nearly 75 years ago on the 16th July, 1945. Their formation was witnessed by a very distinct group of people and this is the story of who those people were and how these glassy rocks came to be.
James Chadwick studied with Ernest Rutherford who developed the nuclear model of atoms, including discovering the proton and theorising neutron which Chadwick discovered - Chadwick realised the neutron would be necessary to induce a nuclear fission reaction. Rutherford died 8 years before the test.
Richard Feynman - working on how much fissile material was needed, and worked on the project while his wife was very ill with Tuberculosis. She died 1 month before the test. devised procedures to protect the staff from radiation poisoning.
J. Robert Oppenheimer - ran the manhattan project, built Los Alomos labs and named the test Trinity.
Arthur Compton working with Enrico Fermi - first sustained nuclear reaction. Fermi worked out how to make new isotopes with neutrons.
Glenn Seaborg - led the team that was responsible for devising the chemical process for the separation, concentration and isolation of plutonium. Campaigner for the peaceful use of atomic energy and against the testing of nuclear weapons. Died 1999 and generated gold through nuclear transmutation.