Barium metal is one of the alkali-earths metals. Barium metal is solid and golden-grey at standard pressure and temperature, it is a very strong metal, but less than Beryllium. Barium metal reacts fast with water producing Hydrogen gas and barium hydroxide. Moreover it reacts with air producing a black film on its surface due to the presence of oxide, for that reason we put barium metal in high quality mineral oil or in argon sealed ampoule. Barium metal is hardly used except as a getter material, which binds unwanted rest gases in vacuum tubes. Barium compounds are scarcely used too, water soluble compounds of it are toxic.
The non-water-soluble barium sulfate, know as barium meal, is used as a radiographic contrast medium.