Copper and its alloys are important commercial metals, widely valued for their exceptional electrical and thermal conductivity, excellent corrosion resistance, and ease of fabrication.
Its ductility and malleability make copper a suitable material for building architecturally specific roofs. Domes and other curved roof shapes can be easily constructed with copper. Another advantage of copper roofing systems is that they are relatively easy to repair.
When exposed to oxygen, moisture, or rain, the surface of copper undergoes a transformation from its initial red color—due to cuprous oxide (Cu₂O)—to green. This change is influenced by environmental factors such as atmospheric pollutants, including sulfur, sulfates, carbon dioxide, etc.
Upon atmospheric exposure, the shiny copper surface first develops a dull tan tarnish as it oxidizes. Over several years, this tarnish darkens to brown or black. Eventually, the corrosion products react with environmental elements to form green compounds, including copper sulfates, carbonates, and chloride salts, collectively known as patina.
References:
https://fa.wikipedia.org/wiki/%D8%B3%D9%82%D9%81_%D9%85%D8%B3%DB%8C
Handbook of Engineering Practice of Materials and Corrosion
