In 1789, the German chemist Martin Klaproth discovered the chemical element Uranium. For about 150 years following its discovery, uranium was found to have some of the most wide-reaching effects of any element. Uranium is present in only two to four parts per million in the earth's crust. Few deposits contain uranium in amounts greater the 0.2 percent. Hundreds of minerals, however, contain uranium. For example, uraninite and carnotite are abundant minerals that contain relatively high concentrations of uranium. Pitchblende, known for its use in the early research of radioactive elements, is a variety of uraninite. The U.S. and Canada contain large deposits of uranium. Auatralia has rich deposits of uranium in its Northern Territory. South Africa and Canada have been the chief suppliers of uranium.
