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This is barium.

Symbol Ba
Atomic number 56
Atomic mass 137.33 amu

Barium was discovered in 1808. Shown in the right is a sample of barium in argon. Storing barium in argon minimizes oxidation of the sample.


Like calcium and magnesium, barium is found in minerals and in the sea. Barium occurs in substantial deposits of barytes, BaSO4.

  • Baryte
    Baryte (or barite) is a heavy mineral. Shown here is barite on calcite. It is the most common ore of barium. It is found worldwide in hydrothermal veins or in limestone and other sedimentary rocks. It can be colourless, white, yellow-brown, or blue and is translucent.

Gem-quality baryte are mined in South Dakota, and Arizona. Other good specimens of baryte are found in England, Italy, Sardinia, and the Sahara desert.


Barium is mainly used in:

  • medical procedure. Because barium sulfate, BaSO4, is opaque to x-rays, it is used in x-ray diagnoses of gastrointestinal examinations. The patient drinks a "barium cocktail", a suspension of BaSO4 in water, to outline the stomach and intestines for X-ray examination. Although all soluble barium salts are toxic, the procedure is safe because BaSO4 is essentially insoluble.
  • firework displays. Barium nitrate, Ba(NO3)2, gives fireworks a green colour.

See also

Periodic table of the elements