Barium's atomic number is 56 and its symbol is Ba. Barium is a soft, dark grey alkaline earth metal that is highly reactive. The name “barium” is derived from a Greek word meaning “heavy”. When Barium is exposed to the atmosphere it turns black before being reduced to a white powder. Because it is not naturally found on earth in its elemental form, this metal is produced from different minerals and crystals. Barium does not have many industrial uses, but it is used in the production of TV picture tubes, solder, spark plugs, and bright green fireworks! Medically, barium sulfate is used as a contrasting agent in CT scans. Before the CT scan, patients drink a slurry of this compound which allows the gastrointestinal tract to be imaged from the X-rays. The Barium in this element cube display is encapsulated in a glass ampule filled with argon. This means that the barium will never be reduced to white powder because of oxidation. The glass-filed ampule is suspended in crystal clear Lucite acrylic.