Uraninite

Uraninite contains radioactive uranium. It is recommended to use a Geiger counter to measure radiation levels before handling. Wear gloves and a mask to prevent skin and lung exposure to radioactive dust. Wash your hands and clothes after handling it. Store it in a closed box in a well-ventilated area away from people.

Uraninite is a major ore of uranium. Some of the highest grade uranium ores in the world were found in the Shinkolobwe mine in the Democratic Republic of the Congo (the initial source for the Manhattan Project) and in the Athabasca Basin in northern Saskatchewan, Canada. Another important source of pitchblende is at Great Bear Lake in the Northwest Territories of Canada, 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 is a primary source of uranium, which in turn is used for a variety of purposes, particularly for nuclear power. Because it is radioactive, it can also be used for radiometric dating of rocks, and it historically has been important for understanding the nature of radioactive elements.

The mineral has been known at least since the 15th century from silver mines in the Ore Mountains, on the German/Czech border. The type locality is the historic mining and spa town known as Joachimsthal, the modern day Jáchymov, on the Czech side of the mountains, where F. E. Brückmann described the mineral in 1772. Pitchblende from the Johanngeorgenstadt deposit in Germany was used by M. Klaproth in 1789 to discover the element uranium.

Uraninite used to be known as pitchblende (from pitch, because of its black color, and blende, from blenden meaning "to deceive", a term used by German miners to denote minerals whose density suggested metal content, but whose exploitation, at the time they were named, was either unknown or not economically feasible).