What word often refers specifically to copper oxide?

• A. Verdigris
• B. Tarnish
• C. Oxide
• D. Patina

Answer: (D)

Patina is the term used for the surface film that forms on copper as it ages and reacts with air and moisture. This aging layer is what you typically see on copper in the field, and it often refers specifically to copper oxide as part of that protective coating. Verdigris is a particular green patina that forms as copper acetate under certain chemical conditions, so it’s a specific type of patina rather than the general idea. Tarnish describes any dulling or discoloration on metals from oxidation and other reactions and is not confined to copper or to the oxide layer. Oxide, while technically accurate, is too generic and doesn’t capture the familiar notion of the aging, protective surface layer. So patina is the best fit for a term that’s commonly linked to copper oxide.