Barium carbonate (BaCO3), also known as witherite, is a chemical compound used in rat poison, bricks, ceramic glazes and cement. Is manufactured from natural barium sulfate (barite) by reduction with petcoke and following precipitation with carbon dioxide. Is widely used in the ceramics industry as an ingredient in glazes. It acts as a flux, a matting and crystallizing agent and combines with certain coloring oxides to produce unique colors not easily attainable by other means.