patine

thumb|Copper roof on the Minneapolis City Hall, coated with patina thumb|upright|The Dresden Frauenkirche. The church was destroyed during the [[bombing of Dresden in 1945 and rebuilt from 1993 to 2005 with new material; the stones with the black patina are the parts that survived the firebombing from the original 18th-century church.]] thumb|Pre-colonial copper coin formerly used in the Copper Belt ([[Democratic Republic of the Congo and Zambia). The external layer has been weathered by moisture and rain, leading to the oxidation of copper.]]