verdigris vs viridian

verdigris

noun
  • The colour of this patina or material. 

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

verb
  • To cover, or coat, with verdigris. 

viridian

noun
  • A bluish-green color. 

  • A bluish-green pigment made from chromium sesquioxide. 

adj
  • Of a bluish green colour. 

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