What Is Pitchblende? (Uraninite)

Chemical Composition of Pitchblende

A closeup photograph of a piece of pitchblende, or uraninite — This is a closeup photograph of a piece of pitchblende, or uraninite.
Geomartin/Public Domain/Creative Commons 3.0

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Updated on February 05, 2019

When learning about the element uranium, the term pitchblende commonly pops up. What is pitchblende and what does it have to do with uranium?

Pitchblende, also known by the name uraninite, is a mineral comprised mainly of oxides of the element uranium, UO₂, and UO₃. It is the primary ore of uranium. The mineral is black in color, like 'pitch'. The term 'blende' came from the German miners who believed it contained many different metals all blended together.

Pitchblende Composition

Pitchblende contains many other radioactive elements that can be traced back to the decay of uranium, such as radium, lead, helium, and several actinide elements. In fact, the first discovery of helium on Earth was in pitchblende. Spontaneous fission of uranium-238 leads to the presence of minute quantities of the extremely rare elements technetium (200 pg/kg) and promethium (4 fg/kg).
Pitchblende was the source of discovery for several elements. In 1789, Martin Heinrich Klaproth discovered and identified uranium as a new element from pitchblende. In 1898, Marie and Pierre Curie discovered the element radium while working with pitchblende. In 1895, William Ramsay was the first to isolate helium from pitchblende.

Where to Find Pitchblende

Since the 15th century, pitchblende has been obtained from the silver mines of the Ore Mountains on the German/Czech border. High-quality uranium ores occur in the Athabasca Basin of Saskatchewan, Canada and the Shinkolobwe mine of the Democratic Republic of the Congo. It is also found with silver at Great Bear Lake in the Canadian Northwest Territories. Additional sources occur in Germany, England, Rwanda, Australia, the Czech Republic, and South Africa. In the United States, it is found in Arizona, Colorado, Connecticut, Maine, New Hampshire, New Mexico, North Carolina, and Wyoming.

At or near the mine, the ore is processed to form yellowcake or urania as an intermediate step in the purification of uranium. Yellowcake consists of about 80% uranium oxide.