cupreous vs rufous

cupreous

noun
  • A reddish-brown color, like that of polished copper. 

adj
  • Of a reddish-brown color, like that of polished copper. 

  • Of or of the nature of copper. 

  • Containing copper. 

rufous

noun
  • A reddish-brown colour, as of rust. 

adj
  • of a reddish colour 

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