Copper II carbonate hydroxide on a watch glass Copper II carbonate hydroxide; Cu2(OH)2CO3; Molar mass 221.114 g/mol Also known as cupric carbonate, basic copper carbonate, copper carbonate, Dicopper carbonate dihydroxide, Greenium. It is a chemical compound, often confused with copper II carbonate, which is a white powder. It is the green colour of copper roofs and has been used as a paint pigment for centuries. Its other main use is to remove algae in aquaculture.