eruginous vs verdigris

eruginous

adj
  • resembling the greenish colour of copper rust 

  • pertaining to the nature or substance of copper 

verdigris

verb
  • To cover, or coat, with verdigris. 

noun
  • A blue-green patina or rust that forms on copper-containing metals. 

  • The colour of this patina or material. 

How often have the words eruginous and verdigris occurred in a corpus of books? (source: Google Ngram Viewer )