Basic copper carbonate
![](/Images/godic/202501/27/Copper_carbonate_basic4522.jpg")
![Basic copper(II) carbonate patina on roofs of Château Frontenac.](/Images/godic/202501/27/Château_Frontenac2010_crop_roofs4522.jpg")
Basic copper carbonate normally refers to the compound (Cu2(OH)2CO3) (the mineral malachite). Sometimes the name is used for Cu3(OH)2(CO3)2 (the related mineral azurite). Malachite and azurite can be found in the verdigris patina that is found on weathered brass, bronze, and copper. The composition of the patina can vary, in a maritime environment depending on the environment a basic chloride may be present, in an urban environment basic sulfates may be present.