Polonium the Curies while they were investigating the cause of pitchblende radioactivity. Pitchblende, after removal of the radioactive elements uranium and thorium, was more radioactive than the uranium and thorium combined. This spurred the Curies to search for additional radioactive elements. They first separated out polonium from pitchblende in July 1898, and five months later, also isolated radium. German scientist Willy Marckwald successfully isolated 3 milligrams of polonium in 1902, though at the time he believed it was a new element, which he dubbed "radio-tellurium", and it was not until 1905 that it was demonstrated to be the same as polonium.
Uraninite where it is found in large quantities associated with silver. It also occurs in Australia, the Czech Republic, Germany, England, Rwanda, Namibia and South Africa. In the United States, it can be found in the states of Arizona, Colorado, Connecticut, Maine, New Hampshire, New Mexico, North Carolina and Wyoming. The geologist Charles Steen made a fortune on the production of uraninite in his Mi Vida mine in Moab, Utah. Uranium ore is generally processed close to the mine into yellowcake, which is an intermediate step in the processing of uranium. Uraninite Uraninite, formerly pitchblende, is a radioactive, uranium-rich mineral and