We live in a nuclear age, and uranium is the metallic element that fuels the nuclear power plants of the world; indirectly, it also provides the materials for nuclear weapons. In the near future, countries with significant deposits of uranium may become as politically powerful as were the oil-producing countries in the recent past.

Yet uranium has not always been an important resource. The German chemist Martin Klaproth discovered it by accident in 1789. He had been analyzing a sample of the mineral ore pitchblende from a silver mine in what is today Czechoslovakia. The dark, heavy mineral had been mined in substantial quantities because it was thought to contain some silver. When no silver was found, the pitchblende was thrown away with the debris.

In 1896 the French physicist Henri Becquerel noticed that pitchblende had one very unusual property: photographic plates exposed to a sample of pitchblende reacted as if they had been exposed to light. This property was called radioactivity, but at the time many scientists dismissed it as being of little importance. However, the investigation of what caused the radioactivity was to lead to one of the most significant discoveries in science, a discovery that laid the foundations for modern nuclear physics.