verdigris

[eberntson]

verdigris

noun
[mass noun]
a bright bluish-green encrustation or patina formed on copper or brass by atmospheric oxidation, consisting of basic copper carbonate.
Origin:

Middle English: from Old French verte-gres, earlier vert de Grece 'green of Greece'

Src: Compact OED

[Philip Hudson]

Copper rusts. Silver rusts. Iron rusts. Gold, not so much. The only beautiful rust is that of copper: verdigris. Patina is such a beautiful word. It’s not in the Good Doctor's 100 most beautiful words, but I hope he would have included it if he had chosen 200.