Cobalt(II) carbonate
Cobalt(II) carbonate is the inorganic compound with the formula CoCO. This reddish paramagnetic solid is an intermediate in the hydrometallurgical purification of cobalt from its ores. It is an inorganic pigment, and a precursor to catalysts. Cobalt(II) carbonate also occurs as the rare red/pink mineral spherocobaltite. Preparation and structure. It is prepared by combining solutions cobaltous sulfate and sodium bicarbonate: CoCO adopts a structure like calcite, consisting of cobalt in an octahedral coordination geometry. Reactions. Heating the carbonate, proceeds in a typical way for calcining, except that the material is partially oxidized: The resulting CoO converts reversibly  to CoO at high temperatures. Like most transition metal carbonates, cobalt carbonate is insoluble in water, but is readily attacked by mineral acids: It is used to prepare many coordination complexes. The reaction of cobalt(II) carbonate and acetylacetone in the presence of hydrogen peroxide gives tris(acetylacetonato)cobalt(III). These complexes are chiral and often can be resolved into the individual enantiomers. Uses. Cobalt carbonate is a precursor to cobalt carbonyl and various cobalt salts. It is a component of dietary supplements since cobalt is an essential element. It is a precursor to blue pottery glazes, famously in the case of Delftware. Natural  occurrence. The moderately rare spherocobaltite is the natural form of cobalt carbonate, with good specimens coming especially from the Republic of Congo. Cobaltocalcite is a cobaltiferous calcite variety that is quite similar in habit to spherocobaltite. Safety. The compound is harmful if swallowed, and irritating to eyes and skin.