Nickel carbonate Green crystals that melting at 56c (decomposes); soluble in acid, insoluble in water; used in electroplating, as a catalyst production for organic chemical manufacture, petroleum refining and edible oil hardening. From the industrial perspective, the most important nickel carbonate is basic nickel carbonate with the formula ni4co3(oh)6(h2o)4. Simpler carbonates, ones more likely encountered in the laboratory, are nico3 and its hexahydrate. All are paramagnetic green solid containing ni2+ cations. The basic carbonate is an intermediate in the hydrometallurgical purification of nickel from its ores and is used in electroplating of nickel. Synonyms Nickel(2+) carbonate; carbonic acid, nickel salt, basic; nickelous carbonate; nickel(ii) carbonate; Carbonic acid, nickel(2+) salt (1:1); nickel monocarbonate; basic nickel(ii) carbonate; nickel(2+) carbonate