Heavy white powder used as a pigment in the manufacture of paints, glazes and synthetic marble. When barium hydroxide is used as an alkalizing agent for paper, it can react with carbon dioxide and precipitate as barium carbonate to provide an alkaline reserve. Both barium hydroxide and barium carbonate are highly toxic. Barium carbonate is also used commercially in rat poison, bricks, cement, and mortar. It is occurs in nature as the mineral witherite.
